chapter 7 living things and air

Po Kok Secondary School S.2 Integrated Science Name:

Class: S.2 ( )

Chapter 7

Living things and air

Chapter Page

Searching for information P. 2-3

7.1 What is air made up of P. 4-12

7.2 Breathed air and unbreathed air P. 13-18

7.3 Burning P. 19-24

7.4 How does our body obtain energy P. 25-27

7. Investigation P. 28-30

7.5 How do green plants obtain energy P. 31-35

7.6 Gaseous exchange between living things and the environment P. 36-40

7.7 Effects of smoking and polluted air on our health P. 41-42

Self-evaluation P. 43-444

Living things and air

Self-learning Exercise

A. Searching for information Objective: To learn Science beyond the textbooks.

Instructions:

You should look for an information about “living things and air” by:

1. Searching for information on the internet. (Key words: atmosphere, photosynthesis, gaseous

exchange or air pollution) OR

2. Reading newspaper or science magazines available in the school library OR

3. Visiting Hong Kong Science Museum.

Paste the information collected on the following space. Write a summary and comment for it.

Do you have any question about the information collected? Write a question about “living things

and air” in the space provided.

1. Information about this chapter

Source:

2. Summary and Comment

________________________________________________________________________________________

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3. Questions about this chapter.

________________________________________________________________________________________

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B. Self-learning Exercise You should watch ETV programme (Air and burning) on the following websites:

http://resources.hkedcity.net/resource_detail.php?rid=1307148201 After watching the ETV, you should complete Multiple-choice Questions on the internet given by your

teacher.

Chapter 7.1

What is air made up of Date:____________

A. Vocabularies The following table show basic English terms used in this chapter. Write all their Chinese terms down in

the right column. Find out their pronunciation on the Po Kok website: http://pokok.edu.hk

1. oxygen 6. glowing splint

2. nitrogen 7. hydrogencarbonate

indicator

3. carbon dioixde 8. lime water

4. noble gas 9. relight

5. water vapour 10. dry cobalt chloride

paper

B. Composition of air Air is a __________________________ of gases. It contains ___________________________

__________________________________.

Class Practice Which gas is the most abundant gas in air? ______________________________

nitrogen 78%

oxygen 21%

water vapour (variable)

carbon dioxide

about 0.04% noble gases

0.932%

C Uses of gases Class Practice 1 - Uses of different gases

A) Match each of the gases listed on the left column with its uses.

(i) (ii) (iii) (iv) (v) (vi)

∙(i) to fill some food packages

(a)

(b)

(c)

Oxygen ∙∙

Nitrogen ∙∙∙

Carbon dioxide ∙∙

∙(ii)

∙(iii)

∙(iv)

to store living cells at a very low

temperature.

to cut metals when mixed with gas fuel.

(Supporter of burning)

to help patients who have breathing

problems.

∙(v) to put out fire (as fire extinguishers).

∙(vi) to keep ice-cream cakes frozen.

B) Making sentences:

e.g.

1. Oxygen is used to cut metals when mixed with gas fuel.

2. Oxygen is used to

3. Nitorgen is used to

4. Nitorgen

5.

6.

(A. Gas)+is used to + (B. verb + noun.)

Class Practice 2

Noble gases (貴氣體) are a group of unreactive and colourless gases.

They include helium (氦), argon(氬), neon(氖), etc.

A) Match each of the gases listed on the left column with its uses.

∙ (i) to fill balloons.

(a)

(b)

(c)

Argon∙

Helium∙

Neon∙

∙ (ii) to fill light bulbs.

∙ (iii) to fill advertising lights.


1. Argon is used to

2. Helium is

3. Neon

(B. Gas)+is used to + (B. verb + noun.)

D . Identifying gases

Oxygen, carbon dioxide, nitrogen and water vapour are common gases in the air. What are the

properties of these gases? How can we test for these gases?

Experiment 7.1A

Title: Tests for oxygen, carbon dioxide and nitrogen

Aim: To find out the properties of oxygen, carbon dioxide and nitrogen, and learn how to test for

them

Apparatus and Chemicals:

Test tubes filled with oxygen ×5, test tubes filled with carbon dioxide×5, Test tubes filled with nitrogen ×5, test

tube racks, wooden splints, matches or lighter, limewater

Safety precaution: Wear safety goggles.

Procedure:

1. (a) _______________ the colour of oxygen in the test tubes.

(b) Record its colour in the table on the result part.

2. (a) ___________________ the stopper of a test tube of oxygen.

___________________ the gas towards your nose and smell it.

[Caution: DO NOT breathe in the gas directly]

(b) ___________________ its smell in the table on the result part.

3. (a) Prepare a burning splint. _______________ it into another test tube of oxygen.

(b) _________________ what happens to the splint and ________________the

observation in the table on the result part.

EYE PROTECTIONMUST BE WORN

4. (a) ________________ a glowing splint. ____________ it into another test tube of

oxygen.

(b) _________________ what happens to the splint and ________________the


5. (a) ______________about 2cm3 of hydrogencarbonate indicator into another test tube of

oxygen.

(b) ______________ the test tube and ______________ it gently.

(c) _________________ what happens to the hydrogencarbonate indicator and

________________the observation in the table on the result part.

6. (a) ______________about 2cm3 of lime water into another test tube of oxygen.

(b) ______________ the test tube and ______________ it gently.

(c) _________________ what happens to the lime water and ________________the


7. Repeat steps 1 to 6, using carbon dioxide in place of oxygen.

8. Repeat steps 1 to 6, using nitrogen in place of oxygen.

hydrogencarbonate indicator

Results:

Observation Test result

Oxygen Carbon dioxide Nitrogen

1. colour of gas

2. smell of gas

3. change of burning

splint

4. change of glowing

splint

5. colour change of

hydrogencarbonate

indicator

6. colour change of

limewater

Conclusions:

1. Oxygen can._____________________________________

2. Carbon dioxide can ____________________________________

Carbon dioxide can ___________________________________________

3. There is___________________________ for nitrogen.

Questions:

1. Can we identify oxygen by looking at its colour? Why?

2. Can we identify carbon dioxide by using burning splint and glowing splint? Why?

Test for oxygen and carbon dioxide:

Testing material used Test result

Oxygen

Carbon dioxide

Experiment 7.1B Tittle: Tests for an unknown gas

You are given four stoppered boiling tubes. Two are labelled as ‘gas X’ and two are labelled as ‘gas Y’,

which stand for oxygen or carbon dioxide. Identify gas X and gas Y by doing two simple tests and

complete the table below:

Gas X Gas Y

Test 1

Using ___________________

________________________

Result: Result:

Test 2

Using ___________________

________________________

Result: Result:

The gas is

Experiment 7.1C Tittle: Tests for water and water vapour Aim: To carry out a simple test for water and water vapour Apparatus and Chemicals:

Dry cobalt chloride paper X 2pieces dropper X 1 dry forceps X2 beaker X1

Procedure: 1. Observe the colour of dry cobalt chloride paper in a desiccator. What is its colour?

2. Take out a piece of dry cobalt chloride paper using a pair of dry forceps. Quickly put a drop of water on it using a dropper.

(a) What happens to the cobalt chloride paper? Its colour changes from ____________ to ___________ (b) What can you tell about the use of cobalt chloride paper? It can be used to test for ___________ 3. Using another pair of dry forceps, hold another piece of dry cobalt chloride paper in air for

one to two minute.

(a) What happens to the cobalt chloride paper?

(b) What can you tell about air from this result? Air contains _________________________

Water vapour turns dry cobalt chloride paper from _____________ to __________________.

Dry cobalt

chloride paper

Dry forceps water

Class Practice 3

A) Match each of the gases listed on the left column with the suitable material(s) for testing

the gas and expected result(s).

Gas to be test Material Used Test result

˙ limewater ˙ ˙from blue to pink

Oxygen˙ ˙ hydrogencarbonate

indicator

˙ ˙milky

Carbon dioxide˙ ˙dry cobalt chloride paper ˙ ˙relighted

Water vapour˙ ˙glowing splint ˙ ˙from red to yellow


1. Oxygen turns

2. Carbon dioxide

3. Carbon dioxide

4. Water vapour

(Gas) + turns + (material) + (result)

Chapter 7.2

Breathed air and unbreathed air Date:____________



1. Breathed air 6 Temperature

2 unbreathed air 7 more

3 compare 8 less

4 collect 9 measure

5 Gas jar 10 thermometer

B. Breathed air and unbreathed air We breathe (呼吸) all the time.

Breathed air – the air that we breathe out from our lungs

Unbreathed air – the air that we breathe into our lungs

How are breathed air and unbreathed air different from one another?

Experiment 7.2A Tittle: Comparing the oxygen and carbon dioxide content of breathed air and unbreathed air Aim: To carry out simple tests to compare the content of oxygen and carbon dioxide in breathed and

unbreathed air

Apparatus and Chemicals: Hydrogencarbonate indicator, measuring cylinder, stopwatch, gas jars X 4, glass plates X 4, water trough, bendable straw, wooden splints x 2, gas lighter, labels X 4

Procedure:

Part A. Collecting breathed air and unbreathed air 1. Collect TWO gas jars of breathed air using the method shown below.

water

gas jar fully filled with water

open end of gas jar

blow gently gas jar fully filled with

breathed air

cover the gas jar with a

glass plate

2. Label the two gas jars as ‘breathed air’.

3. Use two other gas jars to collect unbreathed air and label them. (How would you collect unbreathed

air?)

B. Comparing the oxygen content 1. Put a burning splint into a gas jar of breathed air. Start timing immediately with a stopwatch. Stop

timing when the burning splint just goes out. Record the time.

.

2. Repeat step 1 with a gas jar of unbreathed air.

Results:

Breathed air Unbreathed air

Time taken for burning

splint to go out (s)

(a)What can you tell from the results of this experiment?

Breathed air contains ___________ (more / less) oxygen than unbreathed air.

(b) Explain how you get your answer in (a).

cover the gas jar with the

glass plate as much as

possible burning splint just

goes out

start timing stop timing

C. Comparing the carbon dioxide content 1. Add 5 cm3 of hydrogencarbonate indicator into a gas jar of breathed air. Cover the gas jar with a glass

plate immediately and shake the gas jar gently.

2. Observe the colour of the indicator after shaking. Record it in the table.

3. Repeat steps 1 and 2 with a gas jar of unbreathed air.

Results:


Colour of

hydrogencarbonate

indicator after shaking

What can you tell from the results of this experiment? (Hint: Read the tips below.)

Breathed air contains ________________ (more / less) carbon dioxide than unbreathed air.

Colour of hydrogencarbonate indicator in air with different carbon dioxide contents.

Carbon dioxide content

< 0.04% ~ 0.04% > 0.04%

Colour of the indicator

Purple

Red

Yellow

5 cm3

of hydrogencarbonate indicator

Experiment 7.2B Tittle: Comparing the temperature of breathed air and unbreathed air Aim: To find out the difference in temperature between breathed air and unbreathed air.

Apparatus and Chemicals: Reagent bottle, thermometer, bendable straw, cotton wool

Procedure:

1. Set up the apparatus as shown.

2. Measure the temperature of the unbreathed air in side the bottle. Record it in the table.

3. Blow gently into the bottle through the straw 10 times.

Measure the temperature of the breathed air and record it in the table.


Temperature (℃)

What can you tell from the results of this experiment?

The temperature of breathed air is ___________ (higher / lower) than that of unbreathed air.

cotton wool (do not pack it too loosely or too tightly)

bendable straw

thermometer reagent bottle

Experiment 7.2C Tittle: Comparing the temperature of breathed air and unbreathed air Aim: To find out the difference in the content of water vapour between breathed air and unbreathed air.

Apparatus and Chemicals: Dry mirrors X 2, dry forceps X 2, dry cobalt chloride paper X 2pcs

Procedure: 1. Using a pair of dry forceps, hold a piece of dry cobalt chloride paper near a dry mirror. Breathe onto

the paper twice.

(a) What can you see o n the mirror?

___________________________________________________________

(b) What change do you observe in the paper?

___________________________________________________________

2. Using another pair of dry forceps, put another piece of dry cobalt chloride paper on another dry

mirror. Observe any changes in the paper for one to two minute.

Does the paper show any change? If yes, does the change occur more slowly or quickly than that in

step 1?

________________________________________________________________________-

What can you tell from the results of this experiment?

Breathed air contains __________________ (more / less) water vapour than unbreathed air.

Extension Question Where does the water vapour in breathed air come from?

________________________________________________________________________-

Class Practice A) Circle the correct answers in the table below to compare breathed air and unbreathed air.

Unbreathed air Breathed air

Oxygen About 21%

( more / less ) About 16%

( more / less ) Carbon dioxide About 0.04%

( more / less ) About 4%

( more / less ) Water vapour Variable

( more / less ) Saturated

( more / less ) Temperature ( lower / higher ) ( lower / higher )


1.

a. Compared with breathed air, unbreathed air has ________________ oxygen.

b. Compared with breathed air, unbreathed air has ___________________________.

c. Compared with breathed air, ___________________________________________

d. __________________________________________________________________

2.

a. Compared with unbreathed air, breathed air has ____________________________

b. Compared with unbreathed air, _________________________________________

c. __________________________________________________________________

d. __________________________________________________________________

END

Chapter 7.3

Burning Date:______________________



1. Burning 6 temperature

2 Product 7 Word equation

3 Fuel 8 fire extinguisher

4 Fire triangle 9 Fire beater

5 Put out 10 Water bombing

B. What is burning? What happens when burning takes place? What is produced during burning?

Burning is a chemical process involving and .

It produces , and .

Experiment 7.3A Tittle: What is given out when a wooden splint burns? Aim: To find out the product of burning

Apparatus and Chemicals: Gas jar filled with oxygen (covered with a glass plate) X1, Hydrogencarbonate indicator, wooden splint, Dry forceps, gas lighter, dry cobalt chloride paper X1, 10cm3 .measuring cylinder,

Procedure: 1. Put a burning splint into a gas jar filled with oxygen as shown.

2. When the burning splint goes out, take it out and immediately cover the gas jar completely with the

glass plate.

cover the gas jar with the glass plate as much as possible

burning splint

oxygen

immediately

the burning splint

goes out

cover the gas jar

completely

3. Touch the outside of the gas jar with your hand.

(a) What do you feel? My hand feels __________________.

(b) What does this show?

This shows that _________________ energy is given out during burning.

4. (a) Observe the gas jar carefully.

What do you see on the inner wall of the gas jar? _____________________________

(b) Using a pair of dry forceps, take a piece of dry cobalt chloride paper and let it touch the inner

wall of the gas jar. Take it out immediately and cover the gas jar with the glass plate

completely.

(b) (i) What happens to the cobalt chloride paper?

_________________________________________________________

(ii) What does this show?

This shows that _____________________________ is given out during burning.

5. Add 5 cm3 of hydrogencarbonate indicator into the gas jar. Cover the gas jar immediately with the

glass plate and shake the gas jar gently.

(a) What happens to the indicator?

____________________________________

(b) What does this show?

This shows that ___________________ is given out during burning.

The word equation of burning:

cover the gas jar with the

glass plate as much as

possible

immediately

cover the gas jar completely

5 cm3

of hydrogencarbonate indicator

+ + +

C. The fire triangle

Let’s watch the following magic show.

In the Experiment, we understand that burning takes place only when all of the following are present:

(a)

(b)

(c)

These three conditions form a .

If one of them is removed, the fire will go out. So we can apply this principle

to a fire.

Experiment 7.3B Magic tricks in burning (Demonstration) Aim: To find out the conditions for burning

Procedure: A. A magic liquid

Apparatus and Chemicals: Magic liquid 50cm3, wooden splint X1, heat-proof mat, 100cm3 beaker, gas lighter

Your teacher will set fire to a magic liquid inside a beaker. Observe what happens for a few minutes.

(a) What happens after a few minutes?

The fire ________________ (continues to burn / goes out).

(b) In fact, the magic liquid contains water and a liquid fuel. The two liquids do not mix together.

Knowing this, how would you explain your observation?

The (i)_____________________ (liquid fuel / water) floats on the (ii)_______________ (liquid fuel /

water). When it has all burnt, the fire (iii)_______________________ (continues to burn / goes out).

B. A magic glass

Apparatus and Chemicals: Magic glass (cover with a glass plate), gas lighter, 250cm3 beaker, heat-proof mat, candle

Your teacher will light a candle inside a beaker. She/He then turns a magic glass upside down above the

flame (as if pouring something from the glass onto the flame).

burning splint

magic liquid

heat-proof

mat

(a) What happens to the candle?

The candle _____________________ (continues to burn / goes out).

(b) In fact, the glass is filled with carbon dioxide. Knowing this, how would you explain your

observation?

Carbon dioxide is denser than air. It (i)___________ (floats / sinks) and displaces the air in

the beaker. As a result, there is no oxygen around the candle to support burning. So the

candle (ii)__________________ (continues to burn / goes out).

C. A magic paper boat

Your teacher will heat a magic paper boat as shown.

(a) Does the paper boat burn?

It _________________________ (burns / does not burn).

(b) In fact, the paper boat contains water. Knowing this, how would you explain your

observation?

The water absorbs the (i) _________________ from the paper. This keeps the paper boat

at a temperature that is (ii) _______________ (high / not high) enough for burning to take

place.

■ Conclusion:

Considering the results of parts A, B and C, what conditions do you think are necessary for

burning to take place?

Burning takes place when (a)_______________ , (b)________________ , and a sufficiently

high (c)________________ are present.

Class Practice The following photos show some ways to put out hill fires or to prevent them from spreading. Fill in the

blanks to complete the descriptions.

1. We can put out the fire by using fire extinguisher.

The fire extinguishers release carbon dioxide to displace the air

around the fire.

This stops the supply of _______________________ to the

fire.

2. We can put out the fire by spraying water on fire.

Water absorbs heat and becomes steam.

This lowers the _______________________ .

3. We can put out the fire by turning off the stove.

There is no more supply of gas fuel in the stove.


fire.

4. We can put out the fire by hitting the fire with a fire beater (山

火拍).


fire.

5. We can put out the fire by making a fire break (防火帶).

Trees are removed so that a fire cannot spread.


fire.

6. We can put out the fire by using water bombing.

Water poured on the fire absorbs heat.

This lowers the _______________________ .

D. Prevention of fire

Fire is useful in our daily life. For example, we use it to cook and to heat

water. However, an uncontrolled fire is very dangerous. It can damage

property and cause injury or even death. So we should learn how to prevent

fire.

Class Practice

The picture below shows some potential causes of fire in the home.

Circle each of these potential causes. Discuss how each of them could cause a fire.

What to do in case of fire? In case of fire, what should you do?

Keep calm.

Tell everyone in your flat to leave.

DO NOT try to collect anything when you leave.

Close the door when anything when you leave.

Set off the fire alarm on your floor and yell ‘Fire’.

Leave the flat using the nearest stairway.

DO NOT use the lift.

Call the Fire Services Department by dialling ‘999’ when you are safe.

Chapter 7.4

How does our body obtain energy? Date: A. Vocabularies The following table show basic English terms used in this chapter. Write all their Chinese terms down in


1. energy 6 Peanut

2. activities energy content

3. respiration 7 release

4 complicated 8 Flame

5 living cell 9 Burning spoon

B. Food as our source of energy We need energy to carry out various activities in our daily life. Such energy comes from the food we

eat.

How can food give out energy in our body?

Experiment 7.4A Releasing energy from food by burning Aim: To study the release of energy when food is burnt

Apparatus and Chemicals: Peanuts, thermometer, boiling tube, Bunsen burner, stopper (with two holes), heat-proof mat, stand and clamp, gas lighter, burning spoon, 100cm3 beaker

Procedure: 1. Add some water into a boiling tube until it is about one-third full. Stopper the boiling tube

(using a stopper with two holes and a thermometer inserted).

2. Set up the apparatus as shown.

3. Measure the temperature of the water.

The temperature of the water is _____________________°C.

About 1/3

clamp

stand

water

thermometer

4. Put a peanut on a burning spoon and heat it with a Bunsen flame.

5. When the peanut starts to burn, immediately put it under the boiling tube of water.

6. If the peanut stops burning, heat it with a Bunsen flame until it burns again and then repeat step 5.

7. When the peanut is completely burnt, measure the highest temperature of the water reached.

(a) The highest temperature of the water is ___________°C.

(b) What can you tell from the results?

The temperature of the water (i)___________ (increases / decreases). This shows that the

water absorbs (ii)___________ energy from the burning peanut.

(c) What is the energy conversion involved when the peanut is burnt?

The (i)___________ energy stored in the peanut is converted to (ii)___________ energy and

(iii)___________ energy when the peanut is burnt.

Burning When food is burnt in air, the chemical energy stored in it is released in forms of heat and light

energy.

During this process, oxygen is consumed while carbon dioxide and water are produced.

Bunsen burner

Heat-proof mat

peanut Burning spoon

water

Burning peanut

In our body, the chemical energy stored in food is released by respiration. Respiration takes place in

all the time. In this process, food reacts with oxygen to form carbon

dioxide and water. The energy released is used to support our body activities.

The word equation of respiration:

What are the differences between respiration and burning?

Burning Respiration

(1)

Flame exists Flame does not exist

(2)

Takes place at high temperature Takes place at the body temperature (37∘C)

(3)

Simple process Complicated process

(controlled by enzyme)

(4)

Takes place in air Takes place in living cells

(5)

Faster energy released Slower energy released

C.The energy contents of foods

Different foods have different energy contents, i.e. with the

same weight, different foods provide different amount of

energy.

in living cell

+ + + thermometer

stopper with

two holes

boiling tube

water

Objective:

Bring up students using scientific method and problem solving skill

Chapter 7 - Science Investigation

Comparing the amounts of energy in different snacks Date :

1. Introduction

Different foods contain different amounts of energy. Now, let’s modify Experiment 7.3A to compare the

amounts of energy stored in different snacks.

There are three different kinds of snacks:

Peanut Potato chips Biscuits

Which kind of snack does contain the greatest amount of energy?

2. Aim:

.

3.Hypothesis

4. Design experiment

(A) Design concept:

Use five minutes to discuss the experiment design with your classmates, then express your concept

with words or picture.

Concept (Brain storming!):

(B) Duty:

Use one minute to distribute following duty, and fill in the name list below.

Duty Name of students

Experiment supervisor and time counter

Instrument Manager(s)

Experiment technicians

Records and reporter

(C) Apparatus & Material:

You have five minutes, put『』in the box if you need the equipment and material.

boiling tube stopper stand and clamp Bunsen burner

burning spoon thermometer heat-proof mat gas lighter

electronic balance forceps watch glass measuring cylinder

(D) Variables (“3Cs” of a fair test):

Variable to be

changed:

The variable that are studied in experiment.

(only one in each experiment)

Variable(s) to be

kept constant:

The variable that should remain the same within the whole experiment. (e.g.

same temperature, same weight, same volume.)

What to compare: The variable that are being measured in the experiment.

(e.g. temperature, weight, volume.)

Here are the variables in the investigation, put them in table below.

Type of snacks

Mass of snacks

Volume of water

Increase in the temperature of water

Variables to be kept constant (Control Variable)

Variable to be changed (Independent Variable)

What to compare (Dependent Variable)

(E) Procedure:

According to your design concept in Part A, in ten minutes, draw your setup, icon the experimental

devices and complete the steps of your experiment.

(E) Procedure:

Let your teacher checks your experiment design first,

after being approved, carries on the experiment.

1. Measure the _________________of a piece of snack.

2. Add 10cm3 of water to a boiling tube. Measure the ______________ of water.

3. Put the snack in a _______________ and heat it over a Bunsen flame.

4. When the snack starts burning, move the burning spoon to the bottom of _____________.

5. When the snack is completely burned, measure the ______________of water again.

6. Repeat steps 1 to 5 with other types of snacks.

(F) Safety Precautions:

Use two minutes to complete out the safety precautions in this experiment.

i) Must wear e____________________.

ii) Be careful when _____________________________ .

iii) The bulb of the thermometer should be immersed in water but not be touching the bottom

of the boiling tube.

iv) Put the burning spoon on _________________ after burning.

(G) Experiment:

Now you have 20 minutes for your experiment. Teacher’s sign for approval ______________

(H) Result:

Carry on the experiment and fill in the experimental result in the following table: Snack Mass

(g)

Water

temperature at

the beginning

(℃)

Water

temperature after

heating

(℃)

Increase in water

temperature

(℃)

Increase in water

temperature per gram of

snack ( ℃ / g )

Peanut

Potato

chips

Biscuits

(I) Conclusion:

_____________________________ contains the greatest amount of energy.

(J) Discussion:

How can you compare the amount of energy of the snacks according to your experimental results?

END

Chapter 7.5

How do green plants obtain energy? Date:



1. Photosynthesis 6. Convert

2. Raw material 7. Starch

3. Chlorophyll 8. Release

4. Product 9. Iodine

5. By-product 10. Alcohol

B. The process of photosynthesis Like animals, plants also need food for energy. Animals can eat but plants cannot. How do plants obtain

energy?

Green plants make their own food by . There are four main items of photosynthesis.

1. Raw materials: and are the raw materials. Carbon dioxide is

obtained from the , while the water is obtained from the .

2. Energy source: is required in the photosynthesis. It is absorbed by

in the green plants.

3. Product: The food produced is usually stored in form of

. The energy

absorbed by chlorophyll is converted to the

energy stored in food.

4. By-product: is also produced

and is released into the air.

The word equation of photosynthesis is:

light energy

+ chlorophyll +

C. How do we know whether photosynthesis has occurred? To find out whether a green plant has carried out photosynthesis, we can pick a leaf from the plant

and do an iodine test for starch.

Experiment 7.5A Tittle: The iodine test for starch Aim: to understand how the iodine solution use to test for the presence of starch.

Materials and apparatus: iodine solution, beaker, starch solution, dropper, white tile.

Procedure:

1. the colour of iodine solution.

What colour is it?

2. a drop of solution and a drop of water on a white

tile.

3. a drop of solution to each of them. Observe the colour changes and

the results in the table.

Result:

Liquid Colour after adding iodine solution

Starch

Water

Conclusion:

can be used to test for starch.

The colour changes from to when the starch is

present.

The test for starch using iodine solution is called the iodine test.

Experiment 7.5B Tittle: Test for starch in green leaves Aim: to learn how to use iodine test in the leaves of green plants.

Materials and apparatus: potted green plant, iodine solution, 500 cm3 beakers × 2, Bunsen burner,

boiling tube, tripod and wire gauze, white tile, heat-proof mat, glass rod, gas lighter, alcohol.

Safety Precautions: Alcohol is flammable. DO NOT heat it directly over the Bunsen flame.

Ensure that the Bunsen burner has been turned off when you fill the boiling tube with alcohol

starch solution water

iodine solution

Procedure:

1. (a) half a beaker of water.

(b) a leaf from a potted green plant

that has been kept in bright for several hours.

(c) the leaf in the boiling water for about

minutes.

(d) Turn off the .

2. (a) Half-fill a boiling tube with .

(b) Using a , transfer the leaf to the boiling tube.

(c) the boiling tube into the of hot water for about

minutes.

bright light

green plant

beaker

leaf

Bunsen burner

Heat-proof mat

glass rod

alcohol

hot water

boiling water

3. (a)Take the leaf out of the alcohol. What happens to the

leaf and the alcohol?

The leaf becomes and the alcohol

becomes in colour.

(b) Put the leaf in the beaker of hot water for half a

minute. What happens to the leaf?

The leaf becomes .

4. Carefully spread the leaf on a .

a few drops of

solution to it.

What is the colour of the leaf now? What does this

show?

The leaf is now in colour. This shows that is present in

the leaf.

hot water

alcohol

hot water

iodine solution

Class practice

What is the purposes of the step in the experiment 7.4B? Write the letters representing the purposes in the

boxes below.

Step Purpose

1 Put the leaf in boiling water (a) to test for the presence of starch in the leaf.

2 Put the leaf in hot alcohol (b) to wash away the alcohol and to soften the leaf.

3 Put the leaf in the hot water again (c) to kill the leaf cells so that iodine solution can enter cells.

4 Add iodine solution to the leaf (d) to remove the chlorophyll to make the leaf lighter in color

for easy observation of the results in the iodine test.

In the experiment, starch was found to be present in the leaf. So we knew that the green plant had carried

out photosynthesis. How can we know the by-product oxygen that is also produced during

photosynthesis?

Experiment 7.5C Tittle: Testing the gas produced during photosynthesis (demonstration) Aim: to study that oxygen is produced in photosynthesis.

Materials and apparatus: green water plant, wooden splint, sodium hydrogencarbonate solution, gas

lighter, plastic bottle.

Procedure:

1. Put some water plants into a colourless plastic bottle

2. Add sodium hydrogencarbonate solution into the bottle, until the liquid surface is about 5 cm below

the mouth of the bottle.

3. Squeeze the plastic bottle until the liquid surface reaches the mouth of the bottle.

Immediately screw the cap on the bottle tightly. Make sure that there is no air inside the bottle.

4. Place the bottle under bright light for about 1.5 hours.

5. Remove the cap and quickly insert a glowing splint into the neck of the bottle.

(a) What happens to the glowing splint?

__________________________________________________________________

(b) What does the result show?

__________________________________________________________________

glowing splint

Sodium

hydrogencarbonate

solution

Place the bottle

under bright light

for about 1.5 hours

Squeeze the plastic

bottle.

Chapter 7.6

Gaseous exchange between living things and the environment

Date:



1. Gaseous exchange 6 Grasshopper

2. Take in 7 Capillary tube

3. Release 8 towards

4. Control experiment 9 away from

5. consume 10 Soda lime

B. Gaseous exchange in animals In chapter 7.1, we found that breathed air contains less oxygen and more carbon dioxide than breathed air.

Unbreathed air Breathed Air

Oxygen About 21% About 16%

Carbon dioxide About 0.04% About 4%

Why? Let’s study the following experiment to see what happen of the air inside our body.

Experiment 7.6A Tittle: Gaseous exchange of a grasshopper (demonstration) Aim: to compare the gaseous exchange of an insect in the daytime and at night.

Materials and apparatus: grasshoppersX2, red ink, boiling tubes X4, stoppers with capillary tubes X 4,

aluminium foil X2, rulers X4, soda limeX4, wire gauzeX4, labels X4

Procedure:

1. Prepare the set-ups as shown. Place them in a bright place. (Soda lime is used to absorb carbon dioxide.)

2. Measure the distance between the stopper and the red ink marker in each capillary tube. Take

measurements again after five minutes. Record the results in the table.

Set-up Distance between the stopper and the red ink marker (cm)

Just after setting up After five minutes

A

B

(a) What is the function of soda lime used in the above set-up?

______________________________________________________________________________

(b) How would you explain the results in set-up A?

The grasshopper takes in (i)________________ from the air in the boiling tube and releases

(ii)__________________ ; soda lime absorbs (iii)__________________ from the air in the boiling

tube. The total amount of the gas inside the boiling tube (iv)_________________ (increases /

decreases). As a result, the red ink marker moves (v)_________________ (towards / away from) the

boiling tube.

(c) What is the use of set-up B?

There is no grasshopper in set-up B. If there is any change in the position of its red ink marker, it means

there are changes in other factors, e.g. temperature and air pressure. These factors will

(i)___________ (not / also) affect set-up A. By comparing the results in set-ups A and B, we can know

the actual effect brought about by the (ii)________________ in set-up A. Set-up B is known as the

control experiment (對照實驗) for set-up A.

3. Study the design of set-up C as shown below.

What condition does set-up C simulate, compared with set-up A?

Set-up C simulates the condition (a)__________________ (in the daytime / at night) while set-up A

simulates the condition (b)__________________ (in the daytime / at night).

4. How would you set up a control experiment for set-up C? Draw a labelled diagram to show it and call

it set-up D below.

5. Prepare set-ups C and D. Repeat step 2 with them. Record the results in the table below.

Set-up Distance between the stopper and the red ink marker (cm)

Just after setting up After five minutes

C

D

(a) How would you explain the results in set-up C?

____________________________________________________________________

____________________________________________________________________

(b) What is the use of set-up D?

____________________________________________________________________

____________________________________________________________________

6. Comparing the results of set-ups A and C, what do you find out?

____________________________________________________________________

____________________________________________________________________

____________________________________________________________________

After the doing the experiment, we know that gaseous exchange occurs continuously between all

and . Through , animals oxygen from

the environment and carbon dioxide to the environment.

C. Gaseous exchange in green plants Like animal, green plants consume and produce in respiration DAY and

NIGHT. What gases do green plants take in and release when both and

are taking place during daytime? Let’s see the following experiment.

Experiment 7.6B Tittle: Comparing gaseous exchange in green plants during daytime and at night Aim: to compare the gaseous exchange of a green leaf under bright and dark conditions Materials and apparatus: fresh green leaves X 2, thread X 2, aluminium foil X2pcs, hydrogencarbonate indicator,

10cm3 measuring cylinder, stoppered boiling tubes X 4, test tube rack, labels X4

Procedure:

1. Prepare the set-ups as shown.

(a) Which set-ups simulate the condition in the daytime? ___________

(b) Which set-ups simulate the condition at night? ___________

2. Record the colour of the hydrogencarbonate indicator in each set-up in the table.

3. Leave the above set-ups under bright light for one hour. Observe and record the colour of the

hydrogencarbonate indicator in each set-up again.

Set-up Colour of hydrogencarbonate indicator

At the beginning After one hour

A

B

C

D

4. Compare the results in set-ups A and C.

(a) What can you tell from the result observed in set-up A?

______________________________________________________________________

(b) What is the use of set-up C in this experiment?

______________________________________________________________________

______________________________________________________________________

5. Compare the results in set-ups B and D.

(a) What can you tell from the result observed in set-up B?

______________________________________________________________________

(b) What is the use of set-up D in this experiment?

______________________________________________________________________

______________________________________________________________________

Conclusion: Green plants take in ________________ in bright light and release _________________ in the dark.

During daytime, green plants carry out ___________ and .

Under bright light, the rate of photosynthesis is higher than that of respiration. So there is a net release of

. There is a net uptake of _______ .

At night, photosynthesis stops and only respiration occurs. Therefore, green plants take in

________________ and release _______________________ at night.

D. Balance of oxygen and carbon dioxide in nature

is consumed and is released by living things in respiration. At

the same time, the is consumed and is released by the

gree n plants. So the contents of oxygen and carbon dioxide in nature are kept more or less constant.

Class practice 1

Making sentences

1. Oxygen is released by photosynthesis .

2. .

3. .

4.

(C. gas) + is released/consumed by + (B. chemical process).

Chapter 7.7 Effects of smoking and polluted air on our health Date:



1. Tar 7 Nitrogen oxide

2. Carbon monoxide 8 Sulphur dioxide

3. Nicotine 9 Particulate

4 Lung cancer 10 Blood pressure

5 Addiction 11 Heartbeat

6 Passive smoking

B. Smoking and health 1. Harmful substances in cigarette smoke

We all know that smoking is harmful to our health. What substances are released from a light

cigarette? Let’s see one of them in the experiment.

Experiment 7.7 Tittle: Observing the tar in cigarette smoke (demonstration) Aim: to study the presence of tar in cigarette smoke Materials and apparatus:Cigarette, cotton wool, wash bottle with a fitting tube, lighter, transparent plastic tubing

Procedure:

1. Set up a simple cigarette-smoking model as shown.

2. Squeeze the wash bottle and release it. This allows cigarette smoke to pass through the cotton wool

and enter the wash bottle. Repeat this step several times.

What happens to the colour of the cotton wool?

____________________________________________________________________________

Conclusion

In the experiment above, the colour change of the cotton wool is caused by tar. Tar is a brown, sticky

substance. It sticks to the wall of the trachea and air sacs when one smoles.

Health effects of some harmful substances in cigarette smoke.

Harmful substance Physical properties Possible effects

Tar A brown, sticky liquid Causes lung cancer and other respiratory diseases

Turns our teeth and fingernails yellow

Nicotine An oily liquid Leads to an increase in blood pressure

Causes an increase in heartbeat rate, leading to heart

disease in the long term

Causes addiction to smoking

A colourless, odourless

gas

Lowers the oxygen content in blood,

- Headaches and dizziness

- Increased heartbeat for supplying enough oxygen to

the body, resulting in heart disease in the long term

Besides the above harmful effects, babies born to smoking mothers have a birth

weight on average and chance of death.

Passive smoking

Non-smokers may be affected by cigarette smoke through . It

can cause the same harmful effects as smoking. In Hong Kong, laws have been set up to control

smoking in to protect the health of the general public.

B. Air pollution and health Air pollutant Main sources Effects on our health

Sulphur dioxide Power stations cause irritation to our breathing system

Nitrogen oxide Vehicles cause irritation to our breathing system

Carbon monoxide Vehicles lowers the oxygen content in our blood.

Causes headaches, dizziness, fainting or even

death.

Suspended

particulates

Vehicles and factories Cause respiratory problems (eg. Coughing and

wheezing)

Cause respiratory diseases (e.g. bronchitis and

asthma)

Damage lung tissues

Chapter 7 Living things and air

Self-evaluation

After you finished this chapter, Do you understand the content? Put「」in the appropriate box to

indicate your level of understanding.

Chapter Contents Level of understanding

1 2 3 4 5

7.1 What is air made up of Composition of air (P. 4-6)

Identifying gases (P. 7-12)

7.2 Breathed air and

unbreathed air Breathed air and unbreathed air (P.13-18)

7.3 Burning What is burning?(P.19-20)

The fire triangle (P.21-24)

7.4 How does our body Food as our source of energy (P.25-27)

obtain energy The energy contents of foods (P.27)

7. Investigation The amounts of energy in different snacks (P. 28-30)

7.5 How do green plants The process of photosynthesis (P. 31)

obtain energy How do we know whether photosynthesis

has occurred? (P. 32-34)

7.6 Gaseous exchange Gaseous exchange in animals (P. 35-37)

between living things Gaseous exchange in green plants (P. 37-38)

and the environment Balance of oxygen and carbon dioxide in

nature (P. 39)

7.7 Effects of smoking and Smoking and health (P. 40-41)

polluted air on our health Air pollution and health (P.41)

B. Reflection

After finishing this chapter, what have you learnt? Express what you learnt either in words or in pictures

on the space below.

Fully

understand

Do not

understand

C. Draw your「Mind Map」

1) Write down the topic of this chapter on the center of the space below.

2) Branch out the related main points from the center.

3) Use arrows to link the related branch.

D. Feedback from my teacher:

Air

Po Kok Secondary School S.2 Integrated Science Name:

Class: S.2 ( )

Chapter 10

Common Acids and Alkalis

Chapter Page

Self-learning exercise - Searching for information P.2 - 3

10.1 Acids and alkalis in daily life P.4 - 6

10.2 Acids and alkalis in the laboratory P.7 - 9

10.3 Acid-alkali indicator P.10 - 15

10.4 Acids and corrosion P.16 - 20

10.5 Acid rain P.21 – 23

10.6 Safety related to the use of acids and alkalis P.24 - 27

10.7 Neutralization P.28 - 31

10.8 Daily uses of acids and alkalis P.32 - 34

Science Investigation P.35 - 38

Self-evaluation P.39 - 40

Common Acids and Alkalis

Self-learning Exercise

A. Searching for information

Objective: To learn Science beyond the textbooks. Date:

Instructions:

You should look for an information about “ Common Acids and Alkalis” by:

1. Searching for information on the internet. (Key words: acids, alkalis, acid rain or neutralization)

OR

2. Reading newspaper or science magazines available in the school library OR

3. Visiting Hong Kong Science Museum.

4.Paste the information collected on the following space. Write a summary and comment for it.

Do you have any question about the information collected? Write a question about “Common Acids

and Alkalis” in the space provided.

1. Information about this chapter

Source:

2. Summary and Comment

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

3. Questions about this chapter.

________________________________________________________________________________________

________________________________________________________________________________________

________________________________________________________________________________________

B. Self-learning Exercise (ETV) You should watch ETV programme (Acid and Alkaline) on the following websites:

http://resources.hkedcity.net/resource_detail.php?rid=724107303 After watching the ETV, you should complete Multiple-choice Questions on the internet given by your

teacher.

Chapter 10.1

Acids and alkalis in daily life Date:

A. Vocabularies The following table show Chinese terms used in this chapter. Write all their English terms down in the

right column. Find out their pronunciation from the online dictionary.

1. 酸 3. 酸性

2. 鹼 4. 鹼性

5. 中性

B. Acids

Many foods contain .

(For example, , , contain acids)

Many drinks contain . Hence, they are .

(For example, , , are acidic)

Acids taste . (Or Acids give a taste.)

Some (e.g. toilet bowl cleaner) contain acids.

C. Alkalis

Many cleaners contain .

(For example, , , contain alkalis)

Some foods contain . Hence, they are .

(For example, , are alkaline)

Alkalis taste . (Or Alkalis give a taste.)

Alkalis feel .

D. Neutral substances

substances is not acidic and not alkaline.

(For example is neutral)

Class Practice 1 – Acids and alkalis in daily life 1. Are the following food, drinks and cleaners acidic or alkaline?

(a) Orange: (b) Coffee:

(c) Toothpaste: (d) Glass cleaner:

(e) Toilet bowl cleaner: (f) Baking soda:

(g) Distilled water:

2. Which of the following drinks contain acid?

(1) Lemon tea (2) Orange juice (3) Lemon coke

A. (1) and (2) only B. (1) and (3) only

C. (2) and (3) only D. (1), (2) and (3)

3. Give 2 examples of cleaners that contain alkalis.

Example 1: Example 2:

4. Fill in the blanks below

(a) Acids taste

(b) Alkalis taste

5. Check from internet to see whether the following foods are acidic or alkaline.

Apple: Yoghurt:

Class Practice 1 – Making sentence

Food (e.g. Lemon) Food (e.g. orange) acidic.

Drink (e.g. coke) contains acid. Drink (e.g. water) is alkaline.

Cleaner (e.g. soap) alkali. Cleaner (e.g. soap) neutral

1. (a) Lemon contains . It is .

(b) Orange contains .

(c) Tea .

(d) Soap .

(e) Glass cleaner .

END

Chapter 10.2

Acids and alkalis in the laboratory Date:



1. 氫氯酸 6. 腐蝕性

2. 硫酸 7. 刺激性

3. 乙酸 8. 安全措施

4. 氫氧化鈉 9. 緊急處理

5. 氨 10. 傾瀉

B. Common acids and alkalis used in the laboratory:

Common acids used in the laboratory Common alkalis used in the laboratory

1.

2.

3.

1.

2.

C. Safety precautions

Many acids and alkalis are and .

Safety precautions:

Do Don’t

1.

2.

1.

2.

Do NOT

Do wear

Do wear

Do NOT use

D. Emergency treatments

If an accident happens, tell your teacher as soon as possible.

Some emergency treatment:

Accident Emergency treatment

1. Spillage on skin or clothes

2. Getting into the eyes

3. Spillage on the bench or floor

Class Practice 1 – Acids and Alkalis in the laboratory

1. (a) State 2 common acids used in the laboratory.

1: 2:

(b) State 2 common alkalis used in the laboratory.

1: 2:

2. What do the following labels mean?

(a) (b)

3. State three safety precautions when you are using acids/alkalis in the laboratory.

1:

2:

3:

unless your teacher asks you to do so.

4. Describe the emergency treatment if the following accident happens.

(a) Some sodium hydroxide spills on the bench:

Do not

unless

(b) Some sodium hydroxide spills into your eye:

(c) Some hydrochloric acids spills on your skin:

END

Chapter 10.3

Acid-alkali indicator Date:



1. 酸鹼指示劑 4. pH 試紙

2. 石蕊試紙 5. pH 值

3. 通用指示劑 6. Red cabbage

B. Natural acid-alkali indicators

We should NOT test acids and alkalis by tasting, because it is .

Then, how to test?

Experiment 10.3A (Demonstration)

Title: Magic of red carnation extract

Aim: Be aware that some plants can be used to make simple acid-alkali indicators


Red carnation extract, filter paper (with special treatment), spray bottle

Procedure and result:

Your teacher will prepare several pieces of filter paper marked A or B and a spray bottle filled

your teacher is going to show you

(a) What happen when the red carnation extract is sprayed on the different pieces of filter

paper?

(b) Complete the following sentences after your teacher has told you the secret of the magic.

- The teacher used and to mark on filter paper

A and B respectively.

- When the red carnation extract is mixed with , it turns .

- When the red carnation extract is mixed with , it turns .

Experiment 10.3B

Title: Making natural acid-alkali indicators

Aim: Know that some plants can be used to make simple acid-alkali indicators

Student can make simple acid-alkali indicators using some plants and use them to test

acids and alkalis


several red cabbage leaves 1 mortar and 1 pestle

6 test tubes and Several acids/alkalis to be tested.

Safety precaution: 1.

2.

Procedure:

1. some red cabbage leaves into the mortar. Crush them with a pestle.

2. the leaves with about 10 cm3 of water.

3. the red cabbage extract into a test tube.

What is the colour of the red cabbage extract?

4. 2 cm3 of the acids and alkalis to different test tubes.

5. Add a few drops of red cabbage extract to each test tubes and the colour

change.

Conclusion:

Some coloured plant (e.g. red cabbage) can be used as .

An acid-alkali indicator shows in acids and alkalis.

dilute hydrochloric acid

dilute ethanoic acid

distilled water dilute

ammonia solution dilute

sodium hydroxide

.

C. Litmus paper Experiment 10.3C Tittle: Testing acids and alkalis with litmus paper Aim: Student can test acids and alkalis using litmus paper Apparatus and Chemicals:

5 small blue litmus papers 5 small red litmus papers

Several acids/alkalis to be tested.

Procedure and Result:

1. 5 small red litmus papers and 5 small blue litmus papers on a white tile.

2. 2 drops of different acids, alkalis and water on the red litmus papers. the colour.

3. 2 drops of different acids, alkalis and water on the blue litmus papers. the colour.

Litmus paper can be used as .

Conclusion:

When litmus papers are added to solution, the colours are:

Class Practice 1 – Acid-alkali indicators 1. Will the following food, drinks and cleaners turn red litmus paper blue?

(a) Orange: (/) (b) Coffee: (/)

(c) Toothpaste: (/) (d) Glass cleaner: (/)

(e) Toilet bowl cleaner: (/) (f) Baking soda: (/)

(g) Distilled water: (/)

2. Will the following food, drinks and cleaners turn blue litmus paper red?

(a) Orange: (/) (b) Coffee: (/)

(c) Toothpaste: (/) (d) Glass cleaner: (/)

(e) Toilet bowl cleaner: (/) (f) Baking soda: (/)

(g) Distilled water: (/)

dilute

hydrochloric acid

dilute

ethanoic acid distilled water

dilute

ammonia solution

dilute

sodium hydroxide

dilute

hydrochloric acid

dilute

ethanoic acid distilled water Dilute

ammonia solution

dilute

sodium hydroxide

Litmus paper Add to acid Add to neutral solution

Add to alkali

Red litmus paper

Blue litmus paper

D. Universal indicator and the pH scale

can be used to show how acidic or how alkaline a substance is.

(and )

- In substances of different acidity or alkalinity, it shows different .

- Acidity or alkalinity is measured in .

- The pH value of a substance can be checked from the colour chart provided.

Experiment 10.3D

Tittle: Using universal indicator solution

Aim: Student can find out the pH values of acids and alkalis using universal indicator solution


Universal indicator solution Several acids/alkalis to be tested. sugar solution distilled water

9 test tubes and


1. Label 9 test tubes from a to i.

2. 1 cm3 of different solutions in the test tubes.

3. 2 drops of universal indicator solution to each test tube.

4. the test tube gently. the colour.

5. with the pH colour chart to find the pH value of the solutions. the

colour.

Conclusion:

Acidic substances have a pH value .

- If the pH value of a substance is lower, the substance is (more/less) acidic.

Alkaline substances have a pH value .

- If the pH value of a substance is higher, the substance is (more/less) alkaline.

Neutral substances have a pH value .

Experiment 10.3E

Tittle: Measuring pH values of common drinks and cleaners

Aim: Student can find out the pH values of common liquids found at home using pH paper


pH papers


1. Following liquids are provided.

2. 6 pH papers on the white tiles.

3. 1-2 drops of the liquids on the pH papers.

4. the colour and the pH value.

Lemon juice 7-up milk tap water Soda water Glass cleaner

pH value

Acidic/alkaline/

neutral

dilute

hydrochloric acid

dilute

ethanoic acid distilled water

Sugar

solution lime water

dilute

sodium

hydroxide

pH value

Class Practice 2 – Acid-alkali indicators

1. Which of the following can be used to find how alkaline a substance is?

(1) Universal indicator solution (2) pH paper (3) Litmus paper


C. (2) and (3) only D. (1), (2) and (3)

2. Which of the following substances has a pH value smaller than 7?

(1) Lemon juice (2) Baking power (3) Tap water

A. (1) only B. (2) only

C. (1) and (3) only D. (2) and (3) only

3. 5 different liquids (toothpaste, sugar solution, tea, lemon juice, glass cleaner) are provided.

(a)Red litmus paper are added to each of the liquid. Which liquid will turn the paper blue?

(b)pH paper are added to each of the liquid. Which liquid will give a pH value smaller than 7?

(c) Blue litmus paper is added to one of the liquid. It remain blue in colour. When pH paper is

added to the liquid, the pH value is equal to 7. What is the liquid?

END

Chapter 10.4 Classwork

Acids and corrosion Date:



1. 氫氣 6. 鐵

2. 燃燒的木條 7. 大理石

3. 鋅 8. 石灰石

4. 鎂 9. 碳酸鈣

5. 銅 10. 導管

B. Tests for gases We can test different gases using the following methods:

Type of gas Testing method Result

Oxygen Method 1:

Method 2:

Carbon dioxide Method 1:

Method 2:

Water vapour

C. Corrosive effects of acids on metals Experiment 10.4A(i) Tittle: Test for hydrogen Aim: Know the test method for hydrogen and the corresponding result Apparatus and Chemicals:

Test tubes filled with hydrogen

Safety precaution: 1.

2.

Procedure:

1. Prepare a test tube filled with hydrogen.

2. Prepare a burning splint.

3. the stopper and the burning splint next to the mouth of the test tube.

What can be observed?

Conclusion: We can test hydrogen using the following method:

Type of gas Testing method Result

Hydrogen

Experiment 10.4A(ii) Tittle: Reactions of dilute acids with some metals Aim: Observe the reactions between a dilute acid and some metals Apparatus and Chemicals:

Zinc beads Magnesium ribbon Copper strip Iron wire

test tubes, test tube rack and cotton dilute

hydrochloric acid lighter Wooden splint

Procedure:

1. dilute hydrochloric acid to a test tube until it is about one-fifth full.

2. 10 small zinc beads to the acid.


Observation 1: Observation 2:

3. Cover the mouth of the test tube with cotton.

4. Touch the bottom of the test tube after several minutes.

What can be felt?

5. Prepare a burning splint. Remove the stopper and put the burning splint next to the test tube.


6. Repeat the experiment with magnesium ribbon, copper strip and iron wire respectively.

Write down the results in the following table:

Metal Is the reaction vigorous?

(vigorous/ quite vigorous/ slow reaction / no reaction)

What happens to the metal?

(metal decreases in size / size decreases slowly / no

change)

Does the test

tube become

warm?

What happen when to the

burning splint?

Is hydrogen

produced?

Zinc

Magnesium

Copper

Iron

Conclusion:

Some metals (e.g. and ) react with dilute acids.

During the reactions, gas and are produced.

The size of metal ( they are ).

Class Practice 1 – Corrosive effects of acids on metals

1. Which of the following will happen when a burning splint is used to test for hydrogen?

A. The burning splint relights

B. The burning splint turns from red to yellow

C. The burning splint turns milky

D. The burning splint burns with a ‘pop’ sound

2. Which of the following will happen when zinc is put into dilute acid?

(1) gas bubbles are given out

(2) the size decreases

(3) zinc burns with a ‘pop’ sound


C. (2) and (3) only D. (1), (2) and (3)

3. When iron is added to acid, it dissolves slowly and gas bubbles are given out. What can be

concluded from this result?

A. Hydrogen is given out when iron is added to acid.

B. Heat is given out when iron is added to acid.

C. Acid has corrosive effects on iron.

D. The gas bubbles given out can be tested by a burning splint.

4. True or False

(a) When a glowing splint is used to test for hydrogen, the glowing splint relights.

(b) All metals react with dilute acid.

5. A piece of magnesium strip is put into a test tube containing dilute hydrochloric acid. Gas bubbles

are given out.

(a) Write down another TWO observations.

(b) What gas is given off?

(c) Write down the test method of the gas.

6. We should NOT cook acidic food with iron container. Why?

F

T

Marble in dilute

hydrochloric acid

C. Corrosive effects of acids on building materials Experiment 10.4B Tittle: Reactions of dilute acids with some building materials Aim: Observe the reactions between a dilute acid between some building materials Apparatus and Chemicals:

marble limestone sand

test tubes and test tube rack Dilute hydrochloric acid Delivery tube with rubber stopper Lime water

Procedure:

1. lime water to test tube until it is about one-fifth full.

2. a few marble into another test tube. Add dilute hydrochloric acid until it is about

one-fifth full.

3. Fit a delivery tube into test tube with marble. Put the other end into test tube with lime water.

What can be observed to test tube with marble?

Observation 1: Observation 2:

What can be observed to test tube with lime water?

4. Repeat the experiment with limestone and sand respectively. Write down the results in the following table:

Conclusion:

Some building materials (e.g. and ) contains .

These material react with acids and give off .

The sizes of materials (they are ).

Class Practice 2 – Corrosive effects of acids on building materials

1. Which of the following building materials will be corroded by acid?

(1) sand (2) marble (3) limestone


C. (2) and (3) only D. (1), (2) and (3)

2. Which of the following is the gas given off when limestone pieces are added to dilute

hydrochloric acid?

A. Hydrogen B. Oxygen

C. Nitrogen D. Carbon dioxide

3. Marble and limestone contain which can be corroded by acid.

4. A few pieces of marble is added into a test tube containing dilute hydrochloric acid. Gas

bubbles are given out.

(a) What gas is given off?

(b) Write down the test method of the gas.

END

Building

material Is there a reaction? What happens to the solid?

(size decreases / no change)

Are gas bubbles

given out?

What happen to the

lime water?

Is carbon dioxide

produced?

Chapter 10.5

Acid rain Date:



1. 酸雨 6. 工廠

2. 二氧化硫 7. 車輛

3. 氮氧化物 8. 建築物

4. 污染氣體 9. 結構

5. 舊式發電廠 10. 化石燃料

B. Revision

Neutral substances have pH values .

Acidic substances have pH values .

Many acids are either or .

Acids have on some metals.

Acids have on some building materials.

Clean rainwater has a pH value of about .

Rainwater with a pH value smaller than that is called .

C. Causes of acid rain

Sources of pollutant gases:

1.

2.

3.

Acidic pollutant gases:

1.

2.

The gases dissolve in water and form

Acid rain

(They use )

D. Environmental effects of acid rain

Acid rain can corrode and .

Acid rain can water life

(It is because many fish and plants die when pH value of water is )

Acid rain can plants and affect its .

Experiment 10.5

Tittle: Effect of acid rain on the growth of green beans 綠豆

Aim: Know the effect of acid rain on the growth of plants.


Egg carton Dilute sulphuric acid (pH ~2)

Dilute sulphuric acid (pH ~4)

Plastic sheet Green beans

pH papers cotton wool

Safety precaution: 1. Wear safety goggles.

2. Wear gloves.

Procedure:

1. Write down A, B, C on three holes in an egg carton.

2. Place a plastic sheet over the whole egg carton.

3. the holes with cotton wool.

4. small amount of dilute sulphuric acid of pH ~2 to A.

small amount of dilute sulphuric acid of pH ~4 to B.

small amount of tap water to C.

5. 10 green beans onto the cotton wool in each hole.

6. Leave the egg carton on the side bench for about 1 week. Water the beans every 2 days.

Observe and record the results in the table below:

Hole A (pH 2) Hole B (pH 4) Tap water (~pH 6)

Growth of green

beans

Conclusion: What is the effect of the acids on the growth of the green beans?

Class Practice 1 – Acid rain

1. True or False

(a) Rainwater with a pH value of 6 is regarded as acid rain.

(b) Sulphur dioxide is one of the gas which causes acid rain.

2. Which of the following gases cause(s) acid rain?

(1) sulphur dioxide (2) nitrogen oxides (3) carbon dioxide

A. (1) only B. (1) and (2) only

C. (2) and (3) only D. (1), (2) and (3)

3. Which of the following are the sources of sulphur dioxide and nitrogen oxides in the air?

(1) motor vehicles (2) wind power stations (3) factories


C. (2) and (3) only D. (1), (2) and (3)

4. Write down THREE harmful effects of acid rain.

END

F

T

Chapter 10.6

Safety related to the use of acids and alkalis Date:



1. 濃縮的 3. 處理

2. 稀釋的 4. 煙櫃

B. Strong and weak acids/alkalis

Acids / alkalis can be or

Strong acids/alkalis are more or

C. Concentrated and dilute acids/alkalis

Acids / alkalis can be or

acids/alkalis contain a high percentage of acids/alkalis in water.

acids/alkalis contain a low percentage of acids/alkalis in water.

Concentrated acids/alkalis are more or

D. Corrosive and irritant properties of acids and alkalis

Corrosive and irritant properties of acids and alkalis depends on:

- strong / weak : strong acids/alkalis are generally more corrosive or irritant

- concentrated / dilute : concentrated acids/alkalis are generally more corrosive or irritant

Example of acids/alkalis

Example of strong acids

Example of weak acids

Example of strong alkalis

Example of weak alkalis

.

Strong Weak

Concentrated Acid: Alkali:

Acid: Alkali:

Dilute

Acid: Alkali:

Acid: Alkali:

Corrosive/irritant properties

Experiment 10.6 Tittle: Showing the corrosive power of concentrated strong acids and alkalis Aim: Student can observe the corrosive power of concentrated strong acids and alkalis Apparatus and Chemicals: Concentrated sulphuric acid, white cloth 2, test tube × 1, forceps × 1 pair,

Dilute sulphuric acid, chicken feet × 2, glass rod × 1, heat-proof mat 1,

Concentrated sodium hydroxide, candle × 1, droppers × 2, filter paper 1,

rubber bands × 2, 250 cm3 beakers × 1

Safety precaution: 1. Wear safety goggles

2. Wear gloves

Procedure:

A. Corrosive power of concentrated strong acids

1. Use a rubber band to a piece of white cloth on a beaker.

2. a few drops of concentrated sulphuric acid to the white cloth.

What happens after a few minutes?

3. a few drops of dilute sulphuric acid to the white cloth.

What happens after a few minutes?

What can you conclude from the results?

B. Corrosive power of concentrated strong alkalis

1. a chicken foot into a beaker of concentrated sodium hydroxide for two days.

What happens to the chicken foot?

C. Magic show

1. Your teacher will show you a piece of filter paper and heated it over a candle flame.

What happens to the filter paper?

Explain the magic.

Before heating, letters were written on the filter paper using .

When the filter paper is heated, more water is evapourated. The acid becomes .

The acid the paper and the letters appears in black.

Strong acids/alkalis Weak acids/alkalis

Concentrated

Dilute

E. Handling concentrated strong acids and alkalis

F. Proper procedures for diluting concentrated acids and alkalis

When a concentrated acid or alkali is diluted, a large amount of is released

this cause liquid to

Proper procedure for diluting concentrated acids and alkalis:

Wear , and .

Perform dilution in a .

Add the concentrated acid/alkali slowly to

and the solution carefully with a glass rod.

NEVER pour water into a concentrated acid or alkali ! !

Safety procedure Reason

1. Put on To prevent

2. Wear To prevent

3. Wear To prevent

4. Stick

on the surface of the container To warn users about

5. Handle concentrated strong

acids/alkalis in To prevent

water

Concentrated

acid/alkali

water

Class Practice 1 – Safety related to the use of acids and alkalis

1. Which of the following acid(s) is/are strong acid?

(1) ethanoic acid (2) hydrochloric acid (3) sulphuric acid


C. (2) and (3) only D. (1), (2) and (3)

2. True or False:

(a) Concentrated acids are strong. (/)

(b) Weak alkalis are not dangerous. (/)

(c) Dilute acids contain a small percentage of acid in water. (/)

(d) We should wear laboratory coat when handling concentrated acid. (/)

(e) When diluting acid, we should add water into acid. (/)

3. Which of the following are safety procedures that we should do when handling concentrated alkalis?

(1) Wear protective gloves

(2) Handle concentrated alkalis in a fume cupboard

(3) Stick warning label on the surface of container


C. (2) and (3) only D. (1), (2) and (3)

END

Chapter 10.7

Neutralization Date:



1. 中和 3. 鹽

2. 中和作用 4. 氯化鈉

B. The process of neutralization

Experiment 10.7A

Tittle: Neutralizing a dilute acid with a dilute alkali

Aim: Student know that an acid and an alkali can neutralize each other

Student observe the changes in pH in the process of neutralization


Dilute hydrochloric acid, 25 cm3 measuring cylinder, white tile 1,

Dilute sodium hydroxide, 10 cm3 measuring cylinder, droppers × 2,

Universal indicator solution, 100 cm3 conical flask

Safety precaution: 1. Wear safety goggles, 2. Wear gloves

Procedure:

1. Use a 25 cm3 measuring cylinder to 20 cm3 of

dilute hydrochloric acid. Pour the acid to a conical flask.

2. Put the conical flask on a white tile. two

drops of universal indicator solution to the acid and shake

well.

3. the colour change and the pH

value of the acid in the table below.

4. Use a 10 cm3 measuring cylinder to 10

cm3 of dilute sodium hydroxide.

5. Use a dropper to 0.5 cm3 of dilute

sodium hydroxide to the conical flask. Shake the

solution. Find out and record the pH value of the

solution.

Result:

Volume of dilute sodium hydroxide added (cm3)

0 1.0 2.0 3.0 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0

pH value of the solution

6. the remaining dilute sodium hydroxide in the dropper back into the measuring cylinder.

Volume of dilute sodium hydroxide inside measuring cylinder:

Volume of dilute sodium hydroxide added to conical flask:

7. Go on adding dilute sodium hydroxide to the conical flask. Record the pH value of the solution in the above

table.

8. Plot a graph to show the above.

Conclusion:

Acids and alkalis each other

The process is called .

Volume (cm3)

2

4

6

8

10

12

14

pH value

0 1 2 3 4 5 6 7 8 9 10 Volume (cm3)

C. Product of neutralization Experiment 10.7B Tittle: Product of neutralization Aim: Student know that a salt is produced in neutralization Apparatus and Chemicals: Dilute hydrochloric acid, 25 cm3 measuring cylinder, Bunsen burner, watch glass, Dilute sodium hydroxide, 10 cm3 measuring cylinder, heat-proof mat, dropper, water, 250 cm3 beaker, wire gauze, glass rod, 100 cm3 beaker, tripod, gas lighter

Safety precaution: 1. Wear safety goggles

2. Wear gloves

Procedure:

1. a neutral solution using the acid and alkali given.

- From experiment 10.7A:

To neutralize 20 cm3 of dilute hydrochloric acid, cm3 of dilute sodium hydroxide is needed.

- Prepare 20 cm3 of dilute hydrochloric acid using the 25 cm3 measuring cylinder.

- Prepare cm3 of dilute sodium hydroxide using the 10 cm3 measuring cylinder.

- the acid and alkali into a 100 cm3 beaker.

2. Use a clean dropper to several drops of neutralized solution to a watch glass.

3. the watch glass over a 250 cm3 beaker with one-third full of hot water.

4. the water by a Bunsen burner.

5. Stop heating when all the liquid in the watch glass has evaporated. Observe what is left in the watch glass.

What is evaporated when the solution is heated?

What is left in the watch glass?

Conclusion:

When an acid and alkali neutralize each other, a and is formed.

+ +

For example:

- hydrochloric + sodium + water

acid hydroxide (table salt)

Class Practice 1 – Safety related to the use of acids and alkalis

1. Which of the following are produced when an acid and an alkali neutralize?

(1) hydrogen (2) water (3) salt


C. (2) and (3) only D. (1), (2) and (3)

2. True or False:

(a) The process of adding water to acids is called neutralization. (/)

(b) Only salt are formed when an acid and an alkali neutralize each other. (/)

3. The chemical name of table salt is

A. calcium chloride B. calcium carbonate

C. sodium chloride D. sodium hydroxide

4. The pH values of five liquids are shown below:

Liquid P Q R S T

pH value 12 9 7 5 2

(a) Which liquid(s) can neutralize liquid P?

(b) What happens to the pH value of liquid S if liquid Q is added to it?

END

Chapter 10.8

Daily uses of acids and alkalis Date:



1. 抗酸劑 11. 螞蟻

2. 舒緩 12. 蜜蜂

3. 胃痛 13. 痛楚

4. 過量 14. 調節

5. 胃 15. 泥土

6. 螫 16. 農作用

7. 咬 17. 工廠

8. 處理 18. 廢料

9. 黃蜂 19. 排放

10. 蚊 20. 食物防腐

B. Uses of neutralization 1. Relieving stomachache Experiment 10.8A Tittle: The use of antacids Aim: Student know the principle of neutralization behind the use of antacids Apparatus and Chemicals: Antacid tablets, 250 cm3 beaker, glass rod, Dilute hydrochloric acid, 100 cm3 measuring cylinder, mortar and pestle, Universal indicator solution, white tile

Safety precaution: 1. Wear safety goggles, 2. Wear gloves

Procedure:

1. Use a 100 cm3 measuring cylinder to 100 cm3 of dilute hydrochloric acid.

the acid to a beaker.

2. Put the beaker on a white tile. two drops of universal indicator solution to the acid

and shake well.

3. the colour and the pH value of the acid in the table below.

4. Crush an antacid tablet in a mortar with a pestile. all the antacid powder into the acid.

5. the solution with a glass rod until the table has completely dissolve.

Measured and the pH value of the resulting solution in the table below:

Result:

Volume of dilute sodium hydroxide added (cm3)

0 1 2 3 4 5 6

pH value of the solution

6. Repeat step 3 and 4 several time.

What is the effect of antacid on the acidic solution?

Is the antacid acidic or alkaine?

Conclusion:

Antacids contain .

They are used to excess acid in the stomach.

2. Treating insect stings and bites

Wasps give stings (i.e. leave alkalis in wound).

We can use a (e.g. vinegar) to neutralize it.

Mosquitoes, ants and bees give stings

We can use a (e.g. baking soda) to neutralize it.

3. Regulating the acidity of soil

Some soils are too for the healthy growth of crops.

Farmer can add a to the pH value to a suitable level.

4. Treating acidic and alkaline industrial waste

Some industries produce highly acidic or alkaline waste.

Acids or alkalis should be added to the waste before discharge.

C. Use of acids and alkalis in household cleaners

Many household cleaners contain or which have cleaning power.

D. Uses of acids in food preservations

Acids such as ethanoic acid can be used to .

Acids can kill and can thus be used to preserve food.

Class Practice 1 – Safety related to the use of acids and alkalis 1. True or False:

(a) We can use antacids to neutralize the excess acid in the stomach. (/) (b) Antacids contains strong alkalis. (/)

(c) Weak alkalis can be added to soil to regulate the acidity of it. (/) (d) Acids can kill micro-organisms. (/)

2. Which of the following can be used to treat mosquito stings?

A. vinegar B. tea C. baking soda solution D. sugar solution

3. Which of the following can be used to preserve food? (1) ethanoic acid (2) distilled water (3) ammonia solution A. (1) only B. (2) only C. (1) and (3) only D. (2) and (3) only

4. What kind of chemical is suitable for treating the following? (a) Excess acid in the stomach:

(b) a wasp sting:

(c) an ant bite:

5. Explain why farmers sometimes add weak alkalis to the soil.

6. Name ONE acid that is suitable for preserving foods.

END

Chapter 10 Common Acids and Alkalis

Science Investigation Date:

Effect of solutions of different pH values on the apple browning

Aim: Bring up students using scientific method and problem solving skill.

1. Introduction

Everyone has experienced the phenomenon of cutting into an apple that a few minutes later begins to

turn brown. Once the apple is cut, the enzyme inside the apple is activated and exposes it to oxygen.

This causes oxidation to occur, thus making the apple brown.

Your teacher will provide solutions of pH values 3, 5, 7 and 9. You will be given 10 cm3 of each

solution. Design and perform an experiment to study the effect of solutions of different pH value on

apple browning.

2. Aim

To find out ___________________________________________________.

3. Hypothesis

_______________________________________________________________________________

4.Design Experiment

(A) Design concept:

Use five minute to discuss the design of experiment with your classmates, then express your

concepts in words or pictures.

Concept (Brain storming!):

(B) Duty:

Use one minute to distribute following duty, and fill in the name list below.

Duty Name of students

Experiment supervisor and time counter

Instrument Manager(s)

Experiment technicians

Records and reporter

(C) Apparatus & Material:

Use three minutes to list the equipment and material that you need in this experiment.

(D) Variables (“3Cs” of a fair test):

Variable to be

changed:

The variable that are studied in experiment.

(only one in each experiment)

Variable(s) to be

kept constant:

The variable that should remain the same within the whole experiment. (e.g.

same temperature, same weight, same volume.)

What to compare: The variable that are being measured in the experiment.

(e.g. temperature, weight, volume.)

Control Variable (Variables to be kept constant)

Independent Variable

(Variable to be changed)

Dependent Variable

(What to compare)

(E) Procedure

According to the concept mentioned above, write down the procedure in point form and drawing in five

minutes.

(F) Safety precautions

State the safety precautions in the experiment.

(F) Experiment:

Now you have 20 minutes for your experiment. Teacher’s sign for approval

Let’s your teacher checks your experiment design first,

after being approved, carries on the experiment.

(G) Result

Record your observations in a table.

pH value of

solution

Appearance of apple cylinders

After 10 mins After 20 mins After 30 mins

3 no browning no browning no browning

5

7

9

Note: The number of ‘’ represents the degree of browning.

(H) Conclusion:

(I) Discussion

1. What acids can we use to prevent the browning of fruit in daily life? Why?

END

Chapter 10 Topic: Common Acids and Alkalis Date:

A. Self-assessment

After you finished this chapter, do you understand the content of the chapter? Scan through your textbook

and put a “” in the appropriate box to indicate your understanding of the content. (5 represents the

highest level of understanding.)

Chapter Contents Level of understanding

1 2 3 4 5

10.1 Acids and Alkalis Acids (P.4) Alkalis (P.5) Neutral substances (P.5)

10.2 Acids and alkalis in

the laboratory

Safety precautions when handling acids and alkalis (P.7) Emergency treatments involving acids and alkalis (P.8-9)

10.3 Acid-Alkali Indicators Natural acid-alkali indicators (P.10-11) Litmus paper (P.12-13) Universal indicator and the pH scale (P.13-15)

10.4 Acids and Corrosion Corrosive effects of acids on metals (P.16-19) Corrosive effects of acids on building materials (P.19-20)

10.5 Acid Rain Causes of acid rain (P.21) Environmental effects of acid rain (P.22-23)

10.6 Safety Related to the

Use of Acids and

Alkalis

Strong and weak acids/ alkalis (P.24) Concentrated and dilute acids/ alkalis (P.25) Corrosive and irritant properties of acids and alkalis

(P.25-27)

Handling concentrated strong acids and alkalis (P.27) Proper procedures for diluting concentrated acids and alkalis

(P.27-28)

10.7 Neutralization The process of neutralization (P.28-29) Products of neutralization (P.29-31)

10.8 Daily Uses of Acids

and Alkalis

Uses of neutralization (P.32-33) Use of acids and alkalis in household cleaners (P.34) Uses of acids in food preservation (P.34)

B. Reflection

After finishing this chapter, what have you learnt? Express what you learnt either in words or in pictures

on the space below.

Fully

understand Do not

understand

C. Draw your「Mind Map」

1) Write down the topic of this chapter on the center of the space below.

2) Branch out the related main points from the center.

3) Use arrows to link the related branch.

D. Feedback from my teacher:

chapter 7 living things and air

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