· web view2020. 8. 31. · 7. cc12 electrodes and half equations (higher) 8. ... this question...

ChemistryKS4 Chemical Changes

Homework Booklet

Name: _________________________________________Class: _________________________________________Teacher: _______________________________________

Read the CC01 sections on your knowledge organisers before you begin.

Comprehension Task The image shows 5 test tubes.

Each contains a metal and some acid

Rank the metals in order of reactivity of 30

Task Numb

er

Homework Task Due Date

Teacher Signature

1 CC01 The Reactivity Series2 CC02 Displacement Reactions

CC03 Extracting Metals3 CC04 Salts from Metals

CC05 Insoluble Bases4 CC06 Making Salts Required Practical5 CC07 Neutralisation and pH scale

CC08 Strong and Weak Acids

6CC09 Introduction to ElectrolysisCC10 Changes at the ElectrodesCC11 Extracting Aluminium

7 CC12 Electrodes and Half Equations (HIGHER)8 CC13 Electrolysis Required Practical

CC 01

The Reactivity Series – I should know… R A G

How to describe the reactions, if any, between common metals and either water or acids.

How the reactivity of metals with water or dilute acid is related to the tendency of the metals to form positive ions.

How to deduce the reactivity of metals based on experimental results.

CC01 Reactivity Series Exam Question Practise

Q1.A student investigated the temperature change in displacement reactions between metals and copper sulfate solution.

The table below shows the student’s results.

Metal Temperature increase in °C

Copper 0

Iron 13

Magnesium 43

Zinc 17

The temperature change depends on the reactivity of the metal.

Comprehension Task The image shows 5 test tubes.

Each contains a metal and some acid

Rank the metals in order of reactivity

[Type Here]

[Type Here]

[Type Here]

of 30

The student’s results are used to place copper, iron, magnesium and zinc in order of their reactivity.

Describe a method to find the position of an unknown metal in this reactivity series.

Your method should give valid results.(4)

Q2.A student investigated the reactivity of three different metals.

This is the method used.

1. Place 1 g of metal powder in a test tube.2. Add 10 cm3 of metal sulfate.3. Wait 1 minute and observe.4. Repeat using the other metals and metal sulfates.

The student placed a tick in the table below if there was a reaction and a cross if there was no reaction.

Zinc Copper Magnesium

Copper sulfate

Magnesium sulfate

Zinc sulfate

[Type Here]

of 30

(a) What is the dependent variable in the investigation?

Tick one box.

Time taken

Type of metal

Volume of metal sulfate

Whether there was a reaction or not

(1)

(b) Give one observation the student could make that shows there is a reaction between zinc and copper sulfate.

(1)

(c) The student used measuring instruments to measure some of the variables.

Draw one line from each variable to the measuring instrument used to measure the variable.

Variable Measuring instrument

Balance

Measuring cylinder

Mass of metal

of 30

powder

Ruler

Burette

Volume of metal sulfate

Thermometer

Test tube

(2)

(d) Use the results shown in table above to place zinc, copper and magnesium in order of reactivity.

Most reactive _____________________

_____________________

Least reactive _____________________(1)

(e) Suggest one reason why the student should not use sodium in this investigation.

(1)

Q3.A student investigated the reactivity of different metals.

The student used the apparatus shown in the figure below.

of 30

The student used four different metals.

The student measured the temperature rise for each metal three times.

The student’s results are shown in the table below.

MetalTemperature rise in °C Mean

temperaturerise in °CTest 1 Test 2 Test 3

Calcium 17.8 16.9 17.5

Iron 6.2 6.0 6.1 6.1

Magnesium 12.5 4.2 12.3 12.4

Zinc 7.8 8.0 7.6 7.8

(a) Give two variables the student should control so that the investigation is a fair test. (2)

(b) One of the results for magnesium is anomalous.

Which result is anomalous?

Suggest one reason why this anomalous result was obtained.(2)

(c) Calculate the mean temperature rise for calcium.

Mean temperature rise = _______________ °C(1)

(d) The temperature rose when the metals were added to sulfuric acid.

Give one other observation that might be made when the metal was added to sulfuric acid.

1.

2.

Result:

Reason:

of 30

How would this observation be different for the different metals? (2)

(e) Aluminium is more reactive than iron and zinc but less reactive than calcium and magnesium.

Predict the temperature rise when aluminium is reacted with dilute hydrochloric acid.

Temperature rise = _______________ °C(1)

CC 02 Displacement Reactions – I should know… R A G

Observation:

Differences:

of 30

What a displacement reaction is. How to predict whether a displacement reaction would

happen based on the reactivity series.

How to write ionic equations for displacement reactions.

CC 03

Extracting metals – I should know… R A G

How to identify whether a substance has been oxidised or reduced in terms of gain or loss of oxygen.

How to interpret or evaluate specific metal extraction processes from given information.

[H] How to identify what species in a given reaction have been oxidised and reduced in terms of gain or loss of electrons or oxygen

CC02 & CC03 Displacement Reactions and Extracting Metals Exam Question

Read the CC02 and CC03 and keyword sections on your knowledge organisers before you begin.

Comprehension Task On the right is a representation of a displacement reaction

In a displacement reaction, a more reactive element displaces (replaces) a less reactive element in a compound. In the example above, element A is more reactive, as it replaces element B in the compound.

Question: Copper powder is mixed with Zinc sulphate. No reaction takes place.

Which metal, Copper or Zinc, is the more reactive metal? Explain how you know.

of 30

Practise

Q1. A teacher burns sodium in oxygen.

(a) Complete the word equation for the reaction.

sodium + oxygen ⟶ ___________________(1)

(b) Why is this an oxidation reaction? (1)

(c) Which metal is found in the Earth as the metal itself?

Tick one box.

Calcium

Gold

Lithium

Potassium

(1)

(d) Iron is found in the Earth as iron oxide (Fe2O3).

Iron oxide is reduced to produce iron.

Balance the equation for the reaction.

Fe2O3 + C → Fe + CO2

(1)

(e) Name the element used to reduce iron oxide. (1)

of 30

(f) What is meant by reduction?

Tick one box.

Gain of iron

Gain of oxide

Loss of iron

Loss of oxygen

(1)

Q2.This question is about metals and metal compounds.

(a) Iron pyrites is an ionic compound.

The diagram below shows a structure for iron pyrites.

Determine the formula of iron pyrites.

Use the diagram above. (1)

Nickel is extracted from nickel oxide by reduction with carbon.

(b) Explain why carbon can be used to extract nickel from nickel oxide. (2)

of 30

Q3.

Sodium displaces titanium from titanium chloride.

TiCl4 + 4 Na ⟶ Ti + 4 NaCl

(a) Sodium atoms are oxidised to sodium ions in this reaction.

Why is this an oxidation reaction? (1)

(b) What element is being reduced in this reaction?

Explain your answer in terms of electrons. (2)

Q4. (a) An equation for the displacement of iodine by chlorine is:

Cl2(aq) + 2KI(aq) → I2 (aq) + 2KCl(aq)

What is the ionic equation for the reaction of chlorine with potassium iodide?

Tick one box.

Cl2 + 2K → 2KCl

2I⁻ + Cl2 → I2 + 2Cl⁻

I⁻ + Cl → I + Cl⁻

I⁻ + K+ → KI

(1)

(b) Sodium hydroxide neutralises sulfuric acid.

The equation for the reaction is:

2NaOH + H2SO4 → Na2SO4 + 2H2O

Write the ionic equation for this neutralisation reaction. Include state symbols. (2)

of 30

CC 04

Salts from metals – I should know… R A G

The general formula for a reaction between an acid and a metal.

How to name salts from different acids. How to use the formula of common ions to deduce the

formulae of salts. [H] How to explain in terms of gain or loss of electrons, that

these are redox reactions.

CC 05

Insoluble bases – I should know… R A G

The difference between a base and an alkali. The general word equation for the reaction of an acid and a

base.

Read the CC 04 and CC05 sections on your knowledge organisers before you begin.

Comprehension Task A scientist was given three powders:

Finely ground calcium metal Calcium carbonate Calcium oxide

Write a short method explaining how the scientist could use the equipment listed to identify which powder was which.

Equipment

Test tubes Hydrochloric acid Limewater Bunsen burner Wooden splints Gas delivery tube Tub of water

of 30

CC 04 and CC05 Salts Exam Question Practise

Q1.

(a) Aluminium oxide reacts with hydrochloric acid to produce a salt.

What is the name of the salt produced?

Tick (✔) one box.

Aluminium chloride

Aluminium nitrate

Aluminium sulfate

Aluminium sulfide

(1)

(b) Complete the following equations with the correct products:

(i) Calcium + Hydrochloric Acid → ________ + ________(1)

(ii) Copper Oxide + Sulphuric Acid → ________ + ________(1)

(iii) Zinc Carbonate + Nitric Acid → ________ + ________ + ________(1)

(iv) Sodium Hydroxide + Nitric Acid → ________ + ________(1)

(v) Complete and balance the equation for the reaction between marble chips and hydrochloric acid.

_________+ _______ → CaCl2 + _______ + _______(2)

(c) Calcium nitrate contains the ions Ca2+ and NO3−

Give the formula of calcium nitrate. (1)

(d) Copper Sulphate contains the ions Cu2+ and SO42-

Give the formula of copper sulphate (1)

of 30

(e) Aluminium Hydroxide contains the ions Al3+ and OH−

Give the formula of aluminium hydroxide (1)

CC 06

Making Salts Required Practical – I should know… R A G

A method for the preparation of a pure, dry sample of a soluble salt from an insoluble oxide or carbonate using a Bunsen burner to heat dilute acid and a water bath or electric heater to evaporate the solution.


Comprehension Task

The images show the three main steps in the “Making Salts” RP. Using the images as a guide, write a method describing how you would make pure, dry crystals of copper sulphate from copper oxide powder and sulphuric acid.

Bullet points are better than prose Explain why you need to do each main step above Make sure to include indications of amounts where appropriate (it is fine to say “add a

reactant until you see a change occur” as long as you specify what change you are looking for)

of 30

CC06 Making Salts RP Exam Question Practise

Q1.A scientist produces zinc iodide (ZnI2).

This is the method used.

1. Weigh 0.500 g of iodine.2. Dissolve the iodine in ethanol.3. Add an excess of zinc.4. Stir the mixture until there is no further change.5. Filter off the excess zinc.6. Evaporate off the ethanol.

(a) Ethanol is flammable.

Suggest how the scientist could carry out Step 6 safely. (1)

(b) Explain why the scientist adds excess zinc rather than excess iodine. (3)

Q2.A student investigated the reaction of copper carbonate with dilute sulfuric acid.

The student used the apparatus shown in the figure below.

(a) Complete the state symbols in the equation.

CuCO3 (___) + H2SO4 (aq) → CuSO4 (aq) + H2O (___) + CO2 (g)(2)

of 30

(b) Why did the balance reading decrease during the reaction?

Tick one box.

The copper carbonate broke down.

A salt was produced in the reaction.

A gas was lost from the flask.

Water was produced in the reaction.

(1)

(c) Describe a safe method for making pure crystals of copper sulfate from copper carbonate and dilute sulfuric acid. Use the information in the figure above to help you.

In your method you should name all of the apparatus you will use. (6)

Q3.Soluble salts are formed by reacting metal oxides with acids.

(a) Give one other type of substance that can react with an acid to form a soluble salt.(1)

(b) Describe a method to make pure, dry crystals of magnesium sulfate from a metal oxide and a dilute acid.

(6)

of 30

CC 07

Neutralisation and pH Scale – I should know… R A G

How to use Universal indicator or other indicators to measure the pH of a solution.

How to use the pH scale to identify acidic or alkaline solutions.

CC08

Strong and weak acids – I should know… R A G

[H] How to use and explain the terms diluted, concentrated, weak and strong in relation to acids.

[H] Describe how the concentration of hydrogen affects pH.

Read the CC07 and CC08 sections on your knowledge organisers before you begin.

Comprehension Task

Explain this image. In your explanation, you should include the following:

What the colours mean What chemical we use to see the colours What the numbers mean What the words mean

of 30

CC07 & CC08 Acids and Neutralisation Exam Question Practise

Q1.This question is about elements in Group 1.

A teacher burns sodium in oxygen.

(a) The teacher dissolves the product of the reaction in water and adds universal indicator.

The universal indicator turns purple.

What is the pH value of the solution?

Tick one box.

(1)

(b) The solution contains a substance with the formula NaOH

Give the name of the substance. (1)

(c) All alkalis contain the same ion.

What is the formula of this ion?

Tick one box.

H+

Na+

OH−

O2−

(1)

Q2.

A neutral solution can be produced when ammonia reacts with an acid.

(a) Give the pH of a neutral solution: (1)

pH:

of 30

(b) Which of these ionic equations shows a neutralisation reaction?

Tick (✔) one box.

H+ + OH⁻ → H2O

NH4+ + OH⁻ → NH4OH

H+ + Cl⁻ → HCI

H+ + H2O → H3O+

(1)

(c) Name the salt produced when ammonia reacts with hydrochloric acid.

_____________________________________(1)

Q3.Citric acid is a weak acid.

Explain what is meant by a weak acid. (2)

Q4.This question is about acids and alkalis.

(a) Dilute hydrochloric acid is a strong acid.

Explain why an acid can be described as both strong and dilute. (2)

(b) A 1.0 × 10−3 mol/dm3 solution of hydrochloric acid has a pH of 3.0

What is the pH of a 1.0 × 10−5 mol/dm3 solution of hydrochloric acid?

pH = ___________________

of 30

(1)

CC09

Introduction to electrolysis – I should know… R A G

What electrolysis is. What types of substances can be electrolysed. How to predict the products of electrolysis.

CC10

Changes at the Electrodes – I should know… R A G

How to describe electrolysis in terms of the movement of ions.

Why water affects the products of electrolysis. How to predict the products of electrolysis of aqueous

solutions containing a single ionic compound.

CC11

Extraction of aluminium – I should know… R A G

Why some metals are extracted with carbon and others by electrolysis.

The process of extracting aluminium from bauxite.

Read the CC09, CC10 and CC11 sections on your knowledge organisers before you begin.

Comprehension Task Electrolysis is used to separate ionic compounds.

The image shows a typical electrolysis setup.

Assume that the - ions are Bromide (Br-) and the + ions are lead (Pb2+)

Answer the following questions:

1. What will form at the positive electrode?2. What will form at the negative electrode?3. Will the bulb light up? 4. The solution is replaced with a powder. Why does the bulb not work?

of 30

CC09, CC10 and CC11 Electrolysis Exam Question Practise

Q1.This question is about zinc.

Figure 1 shows the electrolysis of molten zinc chloride.

(a) Zinc chloride is an ionic substance.Complete the sentence.

When zinc chloride is molten, it will conduct _________________________ .(1)

(b) Zinc ions move towards the negative electrode where they gain electrons to produce zinc.

(i) Name the product formed at the positive electrode.

____________________________________(1)

(ii) Explain why zinc ions move towards the negative electrode. (2)

(iii) What type of reaction occurs when the zinc ions gain electrons?

Tick (✔) one box.

of 30

Neutralisation

Oxidation

Reduction

(1)

Q2.A student investigated the electrolysis of different substances.

Figure 2 shows the apparatus.

Figure 2

(a) Explain why electrolysis would not take place in the apparatus shown in Figure 2. (2)

The student investigated how the volume of gases produced changes with time in the electrolysis of sodium chloride solution.

Figure 3 shows the apparatus.

Figure 3

of 30

(b) The student made an error in selecting the apparatus for this investigation.

How should the apparatus be changed?

Give one reason for your answer. (2)

Another student used the correct apparatus.

This student measured the volumes of gases collected every minute for 20 minutes.

Figure 4 shows the student’s results.

Figure 4

of 30

(c) Describe the trends shown in the results.

Use values from Figure 4.(3)

(d) The number of moles of each gas produced at the electrodes is the same.

No gas escapes from the apparatus.

Suggest one reason for the difference in volume of each gas collected. (1)

Q3.

Aluminium is extracted by electrolysis, as shown below.

of 30

(a) Why can aluminium not be extracted by heating aluminium oxide with carbon? (1)

(b) Explain why aluminium forms at the negative electrode during electrolysis. (3)

(c) Explain how carbon dioxide forms at the positive electrodes during electrolysis. (3)

CC12

Electrodes and half equations [HIGHER] – I should know… R A G

[H] How to investigate the electrolysis of a solution using an inert electrode.

[H] How to write half equations at each electrode.


Comprehension Task When referring to the image, this time assume that:

- ions are Bromide (Br-) + ions are lead (Pb2+)

At the positive electrode:

of 30

CC12 Electrodes and Half Equations Exam Question Practise

Q1.

(a) Complete the half equation for the oxidation reaction of sodium to form a sodium ion (Na+)

Na ⟶ ____________ + ____________(1)

(b) Complete the half equation for the oxidation reaction of calcium to form a calcium ion

Ca ⟶ Ca2+ + ____________(1)

Comprehension Task When referring to the image, this time assume that:

- ions are Bromide (Br-) + ions are lead (Pb2+)

At the positive electrode:

of 30

(c) Complete the half equation for the oxidation reaction of chloride ions to form a chlorine molecule (Cl2)

______Cl- ⟶ Cl2 + ____________(1)

Q2.

A teacher demonstrates the electrolysis of different substances using graphite electrodes.

Figure 5 shows the apparatus used.

Figure 5

The teacher demonstrates the electrolysis of:• molten zinc chloride• potassium bromide solution.

Complete the table below to predict the products.

Choose answers from the box.

chlorine bromine hydrogen oxygen potassium zinc

Substance electrolysed

Product at cathode (negative electrode)

Product at anode (positive electrode)

Molten zinc chloride

Potassium bromide solution

of 30

(4)

Q3.

Magnesium chloride can be electrolysed.

The diagram below shows two experiments for electrolysing magnesium chloride.

(a) Explain why magnesium chloride must be molten or dissolved in water to be electrolysed.

(2)

(b) Explain how magnesium is produced at the negative electrode in Experiment 1. (3)

(c) In Experiment 2 a gas is produced at the negative electrode.Name the gas produced at the negative electrode.

____________________________________(1)

(d) Suggest why magnesium is not produced at the negative electrode in Experiment 2.

(1)

(e) Complete and balance the half equation for the reaction at the positive electrode.

of 30

_____ Cl⁻ → Cl2 + _____(1)

CC13

Electrolysis Required Practical – I should know… R A G

What happens when aqueous solutions are electrolysed using inert electrodes.

CC13 Electrolysis RP Exam Question Practise

Q1.A student makes a hypothesis:

‘When different salt solutions are electrolysed with inert electrodes, the product at the negative electrode is always a metal’.

(a) Describe how you would test this hypothesis in the laboratory.

You should:


Comprehension Task In the space below, sketch a fully labelled diagram showing how you would carry out the electrolysis of Copper Chloride.

Every piece of equipment should be labelled You should include predictions for what will be formed at each electrode An attempt should be made to write half equations for each electrode

of 30

• draw a labelled diagram of the apparatus• give the independent variable• describe what you would see at the negative electrode if the hypothesis is true.

Diagram

(5)

(b) The student’s hypothesis is only partially correct.

Explain why the product at the negative electrode is not always a metal. (2)

(c) Predict the product at the positive electrode in the electrolysis of the following: (2)

Independent variable:

Observation:

Sodium Chloride Prediction:

Copper Sulphate Prediction:

of 30

· web view2020. 8. 31. · 7. cc12 electrodes and half equations (higher) 8. ... this question...

Documents