Name_____________________________

Teaching set_______________________

Northgate GCSE Science.

Knowledge Organiser Chemistry.

This booklet contains questions from topics that are covered in

chemistry. This is to be used throughout your GCSE revision.

Use it to help learn the definitions of common scientific terms.

You can get family members to test your knowledge, make

quizzes, games or flashcards.

As part of your homework mini quizzes will pop up during

lesson time based on the information inside this booklet.

The GCSE textbooks and other digital resources are available

online. www.Kerboodle.com. Your username is your initial and

surname e.g. jsmith and the institution code is po7. You may

also wish to use SAM learning for revision purposes.

Key to using this guide.

If you are entered into triple science you will need to know all of the knowledge

If you are entered into combined science you do not need to revise sections in bold.

If you are entered into combined science foundation you do not need to revise information

in italics.

C1 – Air and Water

1 List the gases released by volcanoes that are thought to have formed the early atmosphere?

Carbon dioxide, water vapour, nitrogen, and small amounts of methane and ammonia.

2 What are thought to be the relative proportions of the gases that formed the early atmosphere?

Little or no oxygen, large amounts of carbon dioxide, large amounts of water vapour and small amounts of other gases.

3 Why can’t we be certain about how the earth’s atmosphere formed?

There is only limited evidence (from rocks) about the earth’s early atmosphere.

4 How were the earth’s oceans formed? Water vapour, released by volcanoes, condensed to form the oceans.

5 Describe the processes, other than photosynthesis, that reduced the amount of carbon dioxide in the atmosphere.

a) Carbon dioxide dissolved into the oceans. b) Dissolved carbon dioxide was incorporated into the shells of marine organisms. c) When marine organisms die their shells can eventually form carbonate rocks.

6 Describe what caused the amount of oxygen in the atmosphere to gradually increase.

The evolution of plants which use CO2 for photosynthesis, and release oxygen, caused the levels of atmospheric O2 to gradually increase to its present level.

7 List the percentages of the gases in our modern atmosphere.

Nitrogen 78%, oxygen 21%, argon 0.9%, carbon dioxide 0.04%.

8 How are small changes in our atmosphere caused by a) Volcanic activity b) Burning fossil fuels c) Farming d) Deforestation

a) Volcanoes release sulphur dioxide b) Burning fossil fuels releases carbon dioxide, carbon monoxide and sulphur dioxide. Vehicle engines can also release nitrogen oxides. c) Cattle and rice fields can release methane. d) Deforestation means that there are fewer trees to remove carbon dioxide from the atmosphere.

9 Describe the chemical test for carbon dioxide. Carbon dioxide turns limewater “milky”.

10 What are the products of the incomplete combustion of hydrocarbons? Why are they different from the products of complete combustion?

Products – carbon monoxide and/or carbon and water. Carbon monoxide (CO) and/or carbon (C) are produced because there is not enough oxygen available to form carbon dioxide (CO2).

11 Why are we concerned about incomplete combustion?

Incomplete combustion can cause the release of carbon monoxide, which is toxic, and damage appliances by producing a build-up off soot (carbon).

12 What effect does carbon monoxide have on the body?

Carbon monoxide is toxic. It reduces the amount of oxygen that can be transported around the body by the blood.

13 What is “acid rain”, and how does it arise? Acid rain is rain that is more acidic than normal. (Rainwater is naturally slightly acidic because of dissolved carbon dioxide, but acid rain has a pH lower than 5.2.) All fossil fuels contain impurities, particularly sulphur. When the fuel is burnt the sulphur combines with oxygen to produce sulphur dioxide gas. When water vapour in the atmosphere condenses the sulphur dioxide gas dissolves in it to form an acidic solution. This can then fall as rain and because it is more acidic than normal rainwater it is called “acid rain”.

14 What are the problems associated with acid rain, and what can we do about it?

Acid rain makes rivers, lakes and soils acidic, harming the organisms living there. Acid rain damages the leaves and roots of plants and trees. Acid rain can speed up the weathering of limestone (rocks or buildings) and marble. To reduce the production of acid rain we can; 1. reduce the amount of sulphur in fuels. 2. Remove acidic gases from power station emissions (by reacting them with wet powdered calcium carbonate).

15 What is the “greenhouse effect”? The greenhouse effect is the natural action of gases in the atmosphere (carbon dioxide, methane and water vapour – so these are called “greenhouse gases”) which trap heat energy from the sun and keep the earth warm. (N.B. It is NOT the same as “global warming” – but can lead to it).

16 What is “climate change” (global warming) and what is thought to cause it?

Climate change refers to an average rise in the mean temperature of the atmosphere (measured as a 30 year rolling average). Significant increases are likely to change global weather patterns. The majority of scientists agree that climate change is caused by an increase in the amount of carbon dioxide in the atmosphere. (N.B. Not all scientists agree that human actions are the cause of climate change.)

17 How can we reduce the amount of carbon dioxide in the atmosphere?

a) use alternative fuels b) plant more trees

18 Explain what biofuels are? A biofuel is any fuel obtained from living or recently dead organisms. Biofuels are RENEWABLE fuels. Biofuels still release carbon dioxide when they are burnt, but they only release the amount of carbon dioxide taken in by the plants grown to produce them. They can be considered carbon neutral.

19 Name a biofuel produced from sugar cane or sugar beet. How is it made, and how is it used?

Ethanol (bioethanol), produced by fermentation of the sugars in sugar cane or beet. Used as a fuel for cars, mixed with petrol reducing the amount of petrol needed.

20 What is the main disadvantage of the use of bioethanol and other biofuels?

Growing the crops used to make biofuels requires land and may affect the availability of land for growing food crops.

21 Describe four characteristics of a good fuel. 1. ignites/burns easily 2. produces little smoke and leaves no residue (ash or other residue) 3. produces a large amount of heat 4. easy to store and transport.

22 What is the cause of a sooty flame. Incomplete combustion. (Not enough oxygen present to convert all the carbon in the hydrocarbon fuel to carbon dioxide, so carbon particles are one of the products)

23 What reaction takes place in a hydrogen fuel cell.

Hydrogen and oxygen are combined to produce water. Energy is released during this reaction and can be used to power vehicles.

24 Give an advantage and a disadvantage of combining hydrogen and oxygen in a fuel cell¸ rather than petrol, as a fuel for cars.

Advantage – hydrogen is a clean fuel. The only product of the combination of hydrogen and oxygen is water. Disadvantage – hydrogen can be explosive/hydrogen is not readily available in filling stations at present/cars would need modification/the process needed to produce the hydrogen fuel results in the production of carbon dioxide.

27 What is an exothermic reaction? A reaction where the products have less energy in their bonds than the reactants. Energy is given out as heat. The surroundings will have a temperature increase.

26 Draw an energy change diagram for an exothermic reaction

Products

Reactants

Reaction progress

Ener

gy (

KJ)

27 What is an endothermic reaction? A reaction where the products have more energy in their bonds than the reactants. Energy is taken in as heat. The surrounding will have a temperature decrease.

28 Draw an energy change diagram for an endothermic reaction

29 What is the formula of methane? CH4

30 What is the displayed formula of methane?

31 How do you calculate the overall energy change

of a reaction? Sum of the energy of bonds broken - sum of energy of bonds made

32 If the calculated energy change is a negative what kind of reaction is it?

Exothermic

33 If the calculated energy change is a positive what kind of reactions is it?

Endothermic

34 Give the word equation for the combustion of methane

methane + oxygen → carbon dioxide + water

35 Describe the process for making potable water from sewage.

From wastewater: screening - removing large solids settlement - solids sink to bottom of tank biological treatment - bacteria break down organic matter final settlement - solids sink to bottom of tank, final filtration to return to the river system From surface water: Screening - removing large objects/leaves Clarification - addition of alum to clump together large particles so they sink to the bottom of the tank. Filtration - to remove fine particles disinfection - addition of chlorine to kill pathogens.

Products

Reactants

Reaction progress

Ener

gy (

KJ)

C2- Chemical patterns

1 Describe the key points of Dalton’s atomic model.

Atoms cannot be split up, created or destroyed. Atoms of an element have the same mass and size Atoms of different elements have different masses and sizes

2 Describe Thomson’s ‘plum-pudding’ model of the atom.

Thomson said an atom consists of tiny, negatively charged electrons dotted about in a positively charged sphere.

3 What did Rutherford fire at a target of gold foil to develop jos model of atomic structure?

Alpha particles

4 How did Bohr’s model of the atom differ from that of Rutherford?

Bohr proposed the idea of electrons orbiting in fixed energy levels or shells.

5 What is the charge and mass of a proton? Charge: +1, mass: 1

6 What is the charge and mass of a neutron? Charge: 0, mass: 1

7 What is the charge and mass of an electron? Charge: -1, mass: negligible

8 How do we calculate the number of protons, neutrons and electrons in an atom?

Atomic number = number of protons. Number of protons = number of electrons Number of neutrons = mass number - atomic number

9 What are isotopes? Two or more forms of the same element that have different numbers of neutrons

10 How did Mendeleev arrange the elements to form the Periodic Table?

In order of increasing atomic mass

11 What were the two key things Mendeleev did when developing his Periodic Table?

He left gaps for undiscovered elements. He predicted the properties of missing elements.

12 How many electrons can the first and second electron shells hold?

First shell up to 2 electrons Second shell up to 8 electrons

13 What is the trend in reactivity of the Group 1 elements?

Group 1 elements increase in reactivity going down the group,

14 What products are formed when a Group 1 element reacts with water?

Metal hydroxide + hydrogen

15 What product is formed when a Group 1 element reacts with chlorine?

Metal Chloride

16 What product is formed when a Group 1 element reacts with air?

Metal oxide

17 What are the trends in physical and chemical properties of the Group 7 elements (halogens)?

going down the group: ● melting points and boiling points increase ● colours get darker ● reactivity decreases

18 What is a displacement reaction? In a displacement reaction a more reactive element will displace a less reactive element from its compound.

19 Draw the electron arrangement for a named element, e.g. sodium

20 What is an ion? An electrically charged (+ or -) atom or group of atoms formed by gaining or losing electrons.

21 Draw the electron arrangement for a named ion, e.g. chloride

22 What is an ionic bond? A strong attractive force that holds ions together in an ionic compound

23 What is a giant ionic lattice? The structure of a solid ionic compound consisting of millions of oppositely charged ions in a regular 3D arrangement.

24 Why do solid ionic compounds not conduct electricity?

The ions in the structure are held in fixed positions and cannot move.

25 Why do ionic compounds conduct electricity when dissolved in water or when molten?

The ions are free to move.

26 What does the word ‘polar’ mean when describing water molecules?

The charges within the molecule are not evenly distributed. One end of the molecule has a small positive charge and the other end a small negative charge.

27 What are the four state symbols? (s) solid, (l) liquid, (g) gas, (aq) aqueous. All must be lower-case.

C3- Chemicals of the natural environment

1 Describe the structure of a metal. Positive metal ions surrounded by a sea of delocalised

electrons.

2 Why do metals conduct electricity? There are free electrons in the metallic structure that can

move. The electrons carry a negative charge.

3 Why are metals malleable? They bend because the ions can slide over one another.

4 How do we obtain a supply of unreactive

elements, like gold and platinum to make

jewellery?

They are found uncombined in the earth, and can be dug

out.

5 Where do we find more reactive metals like iron

or copper?

They are found combined, in ores, in the earth’s crust.

6 What is an “ore”?

An ore is a rock that contains enough of a metal to make it

profitable to extract the metal.

7 Describe how iron is extracted from its ore. Iron ore (iron oxide) is heated with carbon (the iron is

reduced – loses its oxygen to the carbon).

8 Describe how aluminium is extracted from its

ore.

Aluminium is extracted by electrolysis.

9 Explain why aluminium is extracted in this way,

and not by simply heating it with carbon.

Aluminium is a reactive metal.

Reactive metals bond strongly to the other elements in

their ores. It requires a lot of energy to separate a reactive

metal from those other elements. Electrolysis can provide

large amounts of electrical energy to separate the metal

from the other elements in the ore. All reactive metals have

to be extracted by electrolysis. The disadvantage is that

this method is expensive.

10 Explain the observations you would see when a

reactive metal is placed in

a) acids

b) water

a) the reaction would be explosive

b) the reaction will bubble vigorously

11 Explain the pattern of reactivity of the group 1

metals in water.

The group one metals are more reactive as you go down

the group. Lithium is the least reactive, then sodium, then

potassium.

12 Give the general word equation for group 1 and

group 2 metals reacting with water. Metal + Water → Metal hydroxide + Hydrogen

13 What is the formula of a hydroxide ion? OH-

14 Describe what happens during a displacement

reaction between sodium and lithium oxide.

The more reactive metal will displace a less reactive metal

from a compound.

sodium + lithium oxide → sodium oxide + lithium.

This happens as a more reactive metal will form metal

ions more easily.

15 What is meant by “oxidation”? The gain of oxygen. E.g. magnesium is “oxidized” when it

combines with oxygen to form magnesium oxide.

OR loss of electrons during a reaction

16 What is meant by “reduction”? The loss of oxygen. E.g. copper oxide is “reduced” when it

is heated with carbon and the oxygen is transferred to the

carbon to form carbon dioxide and copper metal.

OR gain of electrons during a reaction

17 Name the ONLY metal that “rusts”, and what

compound is formed?

Iron. Iron oxide is formed.

18 What is “corrosion” and how can we prevent it?

Corrosion is the oxidation of metals. (Only the corrosion of

iron is called rusting.) It can be prevented by using a

lubricant, galvanising or painting the surface of the metal.

19 Give two advantages of recycling metals. 1. Recycling preserves the metal as a resource for future

generations.

2. Recycling is less damaging to the environment.

20 What is an “alloy”? An alloy is a mixture of metals.

21 Why does converting a pure metal into an alloy

often increase its strength?

In a pure metal all the atoms are the same size. This

means that the atoms can roll over each other if a force is

applied to the metal, so it is malleable and ductile.

In an alloy the atoms are not all the same size (because

they are not all the same element). This means they

cannot roll over each other so easily, and the alloy is

stronger than the pure metal if a force is applied.

22 What are the two advantages of alloy steels

over pure iron?

Alloy steels have a greater resistance to corrosion.

Alloy steels are stronger.

23 What is electrolysis? Electrolysis is the process by which some compounds can

be split apart, using electricity to give simpler substances.

24 What is a cathode? An electrode with a negative charge, which attracts

cations (positive ions).

25 What is an anode? An electrode with a positive charge, which attracts anions

(negative ions).

26 With what kind of substance can electrolysis

work?

molten or aqueous ionic solutions

It can also be used with molten (liquid) metals to purify

them or to plate a cheaper metal.

27 If using electrolysis on an aqueous solution,

which two extra ions will also be in your

solution?

H+ and OH-

28 If you are using electrolysis on an aqueous

solution with a metal ion above hydrogen on the

reactivity series, what will be produced at the

cathode?

Hydrogen gas

29 If using a sulphate in your electrolysis what will

be produced at the anode?

Oxygen gas

30 Write the half equation for the electrolysis of

acidified water

cathode 2 H+(aq)

+2 e- → H2(g)

anode 4OH- (aq) → H2O(l) +O2(g)+4e-

31 Write the half equation for the electrolysis of zinc

chloride

cathode Zn2+ (aq) +2e_ → Zn(s)

anode 2Cl- (aq) → Cl2(g) + 2e-

32 Explain the term electroplating An object is used as the negative electrode and a thin

layer of metal coats the surface of the object.

33 What is a covalent bond? A pair of shared electrons between two atoms.

34 Draw a dot and cross diagram of hydrogen

35 Draw a dot and cross diagram of methane

36 What is a hydrocarbon? A hydrocarbon is a compound that contains hydrogen and

carbon atoms ONLY.

37 Why doesn’t crude oil have a chemical formula?

Crude oil is a complex mixture of hydrocarbons.

38 With respect to crude oil, what is a “fraction”? A fraction is a simpler, more useful mixture of

hydrocarbons with a similar boiling point, e.g. petrol or

bitumen.

39 What is the name of the process used to separate

crude oil into its fractions?

Fractional distillation.

40 The fractions come off of the fractionating column

in the following order (starting from the top of the

column). Name the uses of each fraction:

a) Refinery gases

b) Petrol

c) Kerosene

d) Diesel oil

e) Fuel oil

f) Bitumen

a) domestic heating and cooking

b) fuel for cars

c) fuel for aircraft

d) fuel for some cars and trains

e) fuel for large ships and in some power stations

f) used to surface roads and roofs

41 Hydrocarbons in different fractions differ from

each other in: Number of carbon atoms in their

molecules, boiling points, ease of ignition

(flammability) and viscosity (stickiness).

a) which fraction has the most carbon atoms in

its molecules (the longest carbon chain)?

b) which fraction has the lowest boiling point?

c) which fraction is the hardest to ignite (least

flammable)?

d) which fraction has the lowest viscosity?

a) bitumen

b) refinery gases

c) bitumen

d) refinery gases

42 What are the reactants and products of the

complete combustion of hydrocarbons?

Reactants – hydrocarbon and oxygen.

Products - carbon dioxide and water

43 Are alkanes saturated or unsaturated? Saturated.(They have no carbon-carbon double bonds that

can open up to bond with any more hydrogen atoms – they

are saturated with hydrogen.)

44 What is the formula for

a) methane

b) ethane

c) propane

d) butane

Draw the structures of these molecules

45 What is the formula for the alkenes

a) ethene

b) propene

c) butene

Draw the structures of these molecules.

What is the chemical test for an alkene?

Test – Alkenes turn bromine water from orange to colourless.

46 a) Explain what “cracking” is, and what products

are made.

b) Why do oil companies bother to carry out

this reaction?

a) Cracking is the splitting (using heat) of a long chain

saturated hydrocarbon (an alkane) to form a shorter

chained alkane and an alkene.

b) Shorter chained hydrocarbons make better fuels. Crude

oil contains too many of the longer chained molecules, so

oil companies crack them to i) make more of the useful

fuels, and ii) make alkenes (which can be used to make

polymers).

47 Why can ethene molecules react with each

other, and what is formed?

Ethene molecules have a carbon-carbon double bond that

can open up and join the ethene molecules (the

monomers) together to make a long chain molecule (the

polymer) called poly(ethene).

48 Name the polymer that is made from the

following monomers;

1. propene

2. chloroethene

3. tetrafluoroethene.

1. Poly(propene)

2. Poly(chloroethene)

3. Poly(tetrafluoroethene) (PTFE)

49 Poly(ethene) is flexible, cheap and a good

insulator. So what uses does it have?

Plastic bags, plastic bottles, cling film and insulation for

electrical wires.

50 What are the two main problems associated with

the widespread use of polymers?

Most polymers are not biodegradable and persist in

landfill sites.

Many polymers produce toxic products when they are

burnt.

51 Name two ways in which we can overcome

problems associated with disposal of polymers.

1. By recycling them.

2. By developing biodegradable polymers.

52 Name and draw the alcohols up to 3 carbons. Methanol, ethanol, propanol.

53 Name and draw the carboxylic acids up to 3

carbons.

Methanoic acid,

ethanoic acid,

propanoic

acid.

54 What is formed when ethanol is oxidised and

how does this relate to the spoiling of wine?

Ethanoic acid is produced. This is what happens to the

alcohol in wine when it is exposed to the air – ethanol is

oxidised to ethanoic acid (wine oxidises to vinegar).

55 What is phytoextraction Plants are used to mop up the toxic minerals left over

from mining. Plants with high tolerance to the toxic

minerals help to clean up the environment.

56 What is bioleaching Using bacteria in old soil heaps to oxidise sulphide

minerals. The heap is then sprayed with sulfuric acid.

The run- off contains copper sulphate the copper is then

displaced by a more reactive metal

C4 - Material choices

1. Name the physical properties of a metal Shiny, malleable, ductile, sonorous, good conduction of electricity and heat.

2 Name the physical properties of a ceramic Dull, brittle, strong under compression and hard

3 Describe a composite material A mixture of more than one type of substance, resulting in a material with improved properties.

4 Name the physical properties of a polymer Flexible, durable and lightweight.

5 Describe the term matrix A component of a composite, which surrounds and

embeds the fibres or particles of the composite.

6 How is stiffness measured? By measuring how much it bends under force. Young’s

modulus - a high score is something that does not bend

easily.

7 How do you measure tensile strength? By measuring how much force it takes to break a material

8 How do you measure density? By measuring the mass and volume.

Density = mass

volume

9 Why is aluminium used to make aircraft bodies?

Aluminium does not corrode and is relatively low density.

10 Why is copper used to make saucepans, water

pipes and for electrical wiring?

Because copper is a good conductor of heat and

electricity, and it does not corrode easily.

11 Why is gold used for jewellery and coinage? Because gold does not corrode, and it is relatively

malleable.

12 Why is steel used to make car bodies and bridges? Steel is strong.

13 What is a homologous series, and what atoms do

they include?

A family of molecules that have similar chemical

properties, such as alkanes, alkenes, alcohols and

carboxylic acids. They always contain carbon and

hydrogen. Alcohols and carboxylic acids also have oxygen

atoms.

14 Why do the boiling points of alkanes and alkenes

increase as you increase the number of carbons?

All molecules in a solid state are held together by

intermolecular bonds. These are weak bonds, which can

be overcome easily to increase the distance between the

molecules. The larger/longer the molecules the more

intermolecular bonds hold them together, therefore

more energy is needed to overcome the bonds.

15 Do simple molecular covalent compounds conduct

electricity?

No, because they don’t have free electrons or ions to carry

the charge.

16 Explain why simple molecular substances have low

melting points?

There are only weak forces of attraction (intermolecular

bonds) between the molecules (even though the covalent

bonds within the molecule are strong).

17 Describe the bonding in a giant molecular

structure.

A covalently bonded substance that is made up of a

repeating pattern over and over, until there are billions of

atoms.

18 Give an example of a substance with a giant

molecular structure.

Diamond, graphite, quartz

19 Why is diamond used in cutting tools? Diamond is very hard because all the carbon atoms are

joined by 4 strong covalent bonds.

20 Why does diamond have such a high melting

point?

In diamond each carbon atom is held in place by 4 strong

covalent bonds and it takes a lot of energy to break these

bonds.

21 Why does graphite conduct electricity? In graphite each carbon forms 3 bonds, this leaves one

electron left over from each carbon atom which sits

between the graphite layers and is free to move and carry

a charge.

22 Why can graphite act as a lubricant? The layers of carbon atoms in graphite are only very

weakly joined and are therefore free to slide past each

other.

23 What is a nanoparticle? A particle that is measured between 1 and 100

nanometres.

24 Describe the properties of graphene ● One atom thick

● Transparent

● Flexible

● Conducts electricity

● 300 times stronger than steel

25 Describe the applications of nanotubes As they conduct electricity they are used for components

in electrical devices. They are strong and used for

reinforcing materials such as sports equipment. They can

be used as catalysts as they have such a large surface area.

They can also act as cages around medicine to deliver it to

the body efficiently.

26 Name some uses of nanoparticles ● antibacterial clothing

● sunscreen

● self-cleaning windows

● sports equipment

27 Describe a potential disadvantage of using

nanoparticles.

They are so small they may be able to pass into the

bloodstream and the brain. It is unknown if a build up of

nanoparticles may be toxic. It is a fairly new technology

and more data is needed.

28 How do you calculate surface area to volume

ratio?

find the surface area

area cm2 = height (cm) x length (cm) x by the number of

faces (6)

Find the volume

Volume cm3 = height (cm) x length (cm) x depth (cm)

Ratio (cm-1) = surface area (cm2)

volume (cm3)

The larger the ratio, the more surface area available for

reactions.

29 What happens to metals at the end of their life? They are put into landfill and are non-biodegradable

30 What is a life cycle assessment? As part of government legislation LCA are completed to

slow the use of non-renewable materials. It involves

collecting data on each stage of use from production to

end of use. Including costs, energy input and output and

water use.

31 Name the ways to prevent corrosion of metals. ● painting

● plating

● coating with plastics

● coating with grease

● sacrificial protection

C5- Chemical analysis

1 What is a formulation? A mixture prepared according to a specific formula

2 What is meant by a ‘pure’ substance? A substance that contains a single element or compound.

3 What factors need to be considered when deciding what grade of purity is needed?

● the amount of impurities and what impurities are ● how the impurities can affect the process ● whether the impurities will end up in the product

4 What effect will impurities have on the melting point of a substance?

Impurities usually lower the melting point. Pure substances have a sharp melting point.

5 Name three uses of chromatography ● to separate chemicals in a mixture ● to check the purity of a chemical ● to purify small samples of a chemical

6 In chromatography, what is the mobile phase? The solvent that carries chemicals from a sample through a chromatographic column or sheet (the bit that moves).

7 In chromatography, what is the stationary phase? The medium through which the mobile phase passes, (the bit that doesn’t move).

8 How does chromatography separate chemicals in a mixture?

If a chemical is attracted more to the mobile phase it moves faster. If a chemical is attracted more to the stationary phase it moves slower.

9 What are reference materials? Known chemicals used in analysis for comparison with unknown chemicals.

10 What is a locating agent? A chemical to show up spots on a chromatogram.

11 What is the formula for calculating retardation factor (Rf)

Rf = distance moved by chemical distance moved by solvent

14 What is qualitative analysis? A method for identifying chemicals present in a sample.

15 What is quantitative analysis? Method to determine amount of a chemical in a sample.

16 What is the difference between a homogeneous and a heterogeneous material?

Homogeneous is uniform throughout (eg water), heterogeneous varies throughout (eg Mars bar).

17 What can flame tests be used for? To identify metal ions in a salt.

18 What colour flame is observed with these ions? ● sodium ● potassium ● calcium ● copper

● yellow ● lilac ● orange/red ● blue/green

19 What is a precipitate? An insoluble solid formed on mixing two solutions.

20 What is the formula and colour of the precipitate formed when sodium hydroxide is added to:

● copper Cu2+ ● iron(II) Fe2+ ● iron(III) Fe3+ ● calcium Ca2+ ● zinc Zn2+

● Cu(OH)2 light blue (insoluble in excess NaOH) ● Fe(OH)2 green (insoluble in excess NaOH) ● Fe(OH)3 red-brown (insoluble in excess NaOH) ● Ca(OH)2 white (insoluble in excess NaOH) ● Zn(OH)2 (soluble in excess NaOH)

21 How is an ionic equation different from a chemical equation?

An ionic equation describes a chemical change by showing only the reacting ions in solution .

22 What is the chemical test for chloride, bromide and iodide ions?

Acidify with dilute nitric acid, add silver nitrate solution. If a chloride is present a white precipitate is formed. If a bromide is present a cream precipitate is formed. If an iodide is present a yellow precipitate is formed.

23 What is the chemical test for sulphate ions? Acidify then add barium chloride solution, if a sulphate is present a white precipitate is formed

24 What is the chemical test for carbonate ions? Add dilute hydrochloric acid, if bubbles form, collect the gas and test with limewater. Limewater turns cloudy

25 What is emission spectroscopy? Analytical technique using a spectrometer in which the spectrum produced by a chemical in a flame is analysed.

26 What advantages/disadvantages does emission spectroscopy have over simple flame tests?

advantages: disadvantage: more sensitive cost more accurate faster

27 State the law of conservation of mass. Total mass of products = the total mass of reactants

28 What is the equation for calculating the number of moles of a substance?

number of moles = mass of substance (g) molar mass (g)

29 What does it mean when a reagent is ‘limiting’? Substance that is used up when reaction is complete.

30 How do you calculate the percentage yield of a product?

percentage yield = actual yield x 100% theoretical yield

31 Why are actual yields less than theoretical yields?

reversible reactions, the reaction may not have finished, reactants or products may be lost during processing

32 What volume does one mole of gas occupy? 24dm3 or 24000cm3

33 What is the equation for calculating the number of moles of a gas?

number of moles = volume (dm3) molar volume (24dm3)

34 What is the equation for calculating the concentration of a solution in g/dm3?

concentration (g/dm3) = mass (g) volume (dm3)

35 What is the equation for calculating the concentration of a solution in mol/dm3?

concentration (mol/dm3) = number of moles volume (dm3)

36 What is the ionic equation for the neutralisation reaction between an acid and an alkali?

H+(aq) + OH-(aq) → H2O(l)

37 Describe how to carry out a titration to find the concentration of a dilute acid solution.

Use a pipette to transfer known volume of acid to a flask fill the burette with alkali, read the volume at the bottom of the meniscus, , add indicator add alkali, dropwise nearer the end-point repeat until two titrations are within 0.1cm3

38 What are repeatable results? A set of data, collected by one person, that are similar

39 What are reproducible results? Data, collected by different people, that are similar

C6- Making Useful Chemicals

1 Name the three types of metal compound that can

neutralise acids.

Metal oxides, metal hydroxides and metal carbonates.

2 What are the products of the reaction between an

acid and a metal?

A salt and hydrogen

3 What are the products of the reaction between an

acid and a metal oxide?

A salt and water.

4 What are the products of the reaction between a

metal hydroxide and an acid?

A salt and water.

5 What are the products of the reaction between a

metal carbonate and an acid?

A salt, carbon dioxide and water.

6 What type of salts are produced by hydrochloric

acid?

Chloride salts

7 What type of salts are produced by sulphuric acid? Sulphate salts

8 What type of salts are produced by nitric acid?

Nitrate salts

9 What is the difference between a strong acid and a

weak acid?

A strong acid ionises completely in water to give H+ ions.

A weak acid only partially ionises.

10 How does increasing the temperature speed up a

reaction?

It gives the particles more energy so they collide more

often and the collisions have more energy.

11 How does increasing the concentration of a solution

speed up a reaction?

It means there are more particles present so it will

increase the number of collisions.

12 Explain how breaking up a solid reactant increases

the rate of reaction.

It increases the surface area of the solid meaning that

more collisions can occur because there are more

particles exposed to the other reactant in the smaller

pieces. This increases the likelihood of a successful

collision.

13 Explain how adding a catalyst speeds up the

reaction.

It speeds up the reaction because the catalyst provides

an alternative route for the reaction with a lower

activation energy.

14 What is a catalyst? A catalyst is a substance that increases the rate of a

reaction but is not used up in the reaction

15 Why do enzymes only function within a narrow

temperature and pH range?

Outside this range the shape of the active site will

change and the enzyme is denatured.

16 What is fermentation? Anaerobic respiration in yeast cells which breaks down

glucose to make ethanol and carbon dioxide.

17 What are feedstocks? Chemicals that feed into an industrial process to make

a chemical product.

18 How can you calculate the rate of a reaction from a

graph?

Calculate the gradient, if the graph is a curve, draw a

tangent at the appropriate time point to find the

gradient.

19 What is a reversible reaction? A chemical change which can go forwards or

backwards depending on the conditions.

20 What is meant when a chemical reaction reaches

dynamic equilibrium?

The forward and backward reactions are occurring at

equal rates.

21 What is Le Chatelier’s principle? The position of an equilibrium will shift to oppose a

change in the reaction conditions.

22 What reaction conditions are used in the Haber

process to make ammonia?

150-300 atmospheres pressure.

400-450oC temperature

iron catalyst

23 Name three essential nutrient elements for plant

growth.

● nitrogen - for making protein in leaves and

stalks

● phosphorous - for root growth and fruit

ripening

● potassium - seed growth and protection

against diseases

24 What is eutrophication? A type of environmental damage where excess nitrate

or phosphate in water causes rapid algal growth,

blocking out light. The resultant death and

decomposition of water plants leads to a reduction in

oxygen levels.

25 What is a batch process? A process where a quantity of product is produced at

one time.

26 What is a continuous flow process? A process used to produce large amounts of product

without stopping the production process.

27 What is the equation for calculating atom

economy?

atom = mass of atoms in useful product x 100% economy mass of atoms in the reactants

How science works

1. What is meant by an outlier? It is a value that is not expected and is caused by random errors. The reading should be taken again or not used during calculations.

2. What is meant by accuracy? describes how close the result is to the true value

3. What is meant by precision? describes the measure of spread in the data, a small spread is more precise.

4. What is the independent variable? The variable that we change in an experiment

5. What is the dependent variable? The variable that is measured.

6. What are control variables? The variables that are kept the same to allow comparisons of the data collected.

7. What is a random error? A source of variation in the measurements that cannot be avoided.

8. What is a systematic error? An error that is the same in all data and repeated. Good examples include using uncalibrated equipment.

9. How should you measure liquids accurately? By taking the measurement from the bottom of the meniscus (bubble). Equipment such as a burette, glass pipette and filler and a volumetric flask are more accurate than beakers and measuring cylinders.

10 What is the standard unit (SI) of: mass length time temperature area volume BMI Light intensity amount of substance concentration density pressure energy

Kilogram (Kg) meters (m) seconds (s) degrees Celsius (oC) or Kelvin (K) meter squared (m2) meter cubed (m3) or decimeter cubed (dm3) Kilogram per meter squared (Kg/m2) watt per meter squared (W/m2) mole (mol) mole per decimeter cubed (mol/dm3) kilogram per meter cubed (Kg/m3) pascals (Pa) joule (J)