Climate Change

Global warming: http://www.youtube.com/watch?v=Z_jHP6xBLe8

The Greenhouse effect: http://www.youtube.com/watch?v=NFXR49hg8II

Sea levels: http://www.bbc.co.uk/learningzone/clips/evidence-for-global-warming-sea-level-change-no-narration/1496.html 

Additional Coursework: Simulating Reactions

This simulation allows you to have a look at how changing different components in a reaction can have an effect on the rate. It's a little complicated, and more detailed than you'll need for your coursework, but playing with it will help you get comfortable with how to control a reaction: http://phet.colorado.edu/en/simulation/reactions-and-rates

The Rate Experiments tab is probably the best one for the coursework.

Additional Science Coursework: Rates of Reaction

This year's Additional coursework is investigating the factors that affect how quickly a reaction takes place. As part of the write-up you will need to explain why the rate of a reaction is affected by these factors. While this link from BBC Bitesize is based on a different exam board (AQA rather than OCR), it covers the basics of a reaction well: http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa/reaction/ratesrev1.shtml 

C6 Specification

Module C6: Chemical Synthesis

C6.1 Chemicals and why we need them

1. understand the importance of chemical synthesis to provide food additives, fertilisers,

dyestuffs, paints, pigments and pharmaceuticals

2. interpret information about the sectors, scale and importance of chemical synthesis in

industry and in laboratories

3. recall the formulae of the following chemicals: chlorine gas, hydrogen gas, nitrogen gas,

oxygen gas, hydrochloric acid, nitric acid, sulfuric acid, sodium hydroxide, sodium chloride,

sodium carbonate, sodium nitrate, sodium sulfate, potassium chloride, magnesium oxide,

magnesium hydroxide, magnesium carbonate, magnesium chloride, magnesium sulfate,

calcium carbonate, calcium chloride and calcium sulfate

4. work out the formulae of ionic compounds given the charges on the ions

5. work out the charge on one ion given the formula of a salt and the charge on the other

ion

6. recall the main hazard symbols and be able to give the safety precautions for handling

hazardous chemicals (limited to explosive, toxic, corrosive, oxidizing, and highly flammable)

7. recall examples of pure acidic compounds that are solids (citric and tartaric acids), liquids

(sulfuric, nitric and ethanoic acids) or gases (hydrogen chloride)

8. recall that common alkalis include the hydroxides of sodium, potassium and calcium

9. recall the pH scale

10. recall the use of litmus paper, universal indicator and pH meters to detect acidity and

alkalinity, and the use of universal indicator and pH meters to measure pH

11. recall the characteristic reactions of acids that produce salts, to include the reactions with

metals and their oxides, hydroxides and carbonates

12. write word equations when given appropriate information

13. interpret symbol equations, including the number of atoms of each element, the number

of molecules of each element or covalent compound and the number of ‘formulas’ of ionic

compounds, in reactants and products

In this context, ‘formula’ is used in the case of ionic compounds as an equivalent

to molecules in covalent compounds; the concept of the mole is not covered in the

specification

14. balance unbalanced symbol equations

15. write balanced equations, including the state symbols (s), (l ), (g) and (aq), to describe

the characteristic reactions of acids and other reactions when given appropriate

information

16. recall the state symbols (s), (l ), (g) and (aq) and understand their use in equations

17. recall that the reaction of an acid with an alkali to form a salt is a neutralisation reaction

18. explain that acidic compounds produce aqueous hydrogen ions, H+(aq), when they dissolve

in water

19. explain that alkaline compounds produce aqueous hydroxide ions, OH–(aq), when they

dissolve in water

20. write down the name of the salt produced given the names of the acid and alkali

21. write down the formula of the salt produced given the formulae of the acid and alkali

22. explain that during a neutralisation reaction, the hydrogen ions from the acid react with

hydroxide ions from the alkali to make water:

H+(aq) + OH−(aq) → H2O(l )

23. understand the terms endothermic and exothermic

24. use and interpret simple energy level diagrams for endothermic and exothermic reactions

25. understand the importance of the energy change during a reaction to the management and

control of a chemical reaction.

C6.2 Planning, carrying out and controlling a chemical synthesis

1. identify the stages in a given chemical synthesis of an inorganic compound (limited to acidalkali

reactions), including:

a. choosing the reaction or series of reactions to make the required product

b. carrying out a risk assessment

c. working out the quantities of reactants to use

d. carrying out the reaction in suitable apparatus in the right conditions (such as

temperature, concentration)

e. separating the product from the reaction mixture (limited to filtration)

f. purifying the product (limited to evaporation, crystallisation and drying in an oven or

desiccator)

g. measuring the yield and checking the purity of the product (by titration)

2. understand the purpose of these techniques: dissolving, crystallisation, filtration,

evaporation, drying in an oven or desiccator

3. understand the importance of purifying chemicals and checking their purity

4. understand that a balanced equation for a chemical reaction shows the relative numbers of

atoms and molecules of reactants and products taking part in the reaction

5. understand that the relative atomic mass of an element shows the mass of its atom relative

to the mass of other atoms

6. use the Periodic Table to obtain the relative atomic masses of elements

7. calculate the relative formula mass of a compound using the formula and the relative atomic

masses of the atoms it contains

8. substitute relative formula masses and data into a given mathematical formula to calculate

reacting masses and/or products from a chemical reaction

9. calculate the masses of reactants and products from balanced equations

10. calculate percentage yields given the actual and the theoretical yield

11. describe how to carry out an acid-alkali titration accurately, when starting with a solution or a

solid to be dissolved to make up a solution

12. substitute results in a given mathematical formula to interpret titration results quantitatively

13. understand why it is important to control the rate of a chemical reaction (to include safety

and economic factors)

14. explain what is meant by the term ‘rate of chemical reaction’

15. describe methods for following the rate of a reaction (for example, by collecting a gas,

weighing the reaction mixture or observing the formation or loss of a colour or precipitate)

16. interpret results from experiments that investigate rates of reactions

17. understand how reaction rates vary with the size of solid particles, the concentration of

solutions of chemicals and the temperature of the reaction mixture

18. understand that catalysts speed up chemical reactions while not being used up in the

reaction

19. interpret information about the control of rates of reaction in chemical synthesis

20. use simple ideas about collisions to explain how chemical reactions take place

21. use simple collision theory and ideas about collision frequency to explain how rates of

reaction depend on the size of solid particles and on the concentration of solutions of

dissolved chemicals.

The effect of temperature on collision frequency is not considered since activation energy has a greater influence

© OCR 2011 GCSE Science A

C4 Specification

Module C4: Chemical Patterns

C4.1 What are the patterns in the properties of elements?

1. understand that atoms of each element have different proton numbers

2. understand that arranging the elements in order of their proton numbers gives repeating

patterns in the properties of elements

3. understand that early attempts to find connections between the chemical properties of the

elements and their relative atomic mass were dismissed by the scientific community

4. recall the significant stages in the history of the development of the Periodic Table to include

the ideas of Döbereiner, Newlands and Mendeleev

5. understand how Mendeleev used his Periodic Table to predict the existence of unknown

elements

6. use the Periodic Table to obtain the names, symbols, relative atomic masses and proton

numbers of elements

7. understand that a group of elements is a vertical column in the Periodic Table and that the

elements in a group have similar properties

8. recall that a period is a row of elements in the Periodic Table

9. use the Periodic Table to classify an element as a metal or non-metal

10. use patterns in the Periodic Table to interpret data and predict properties of elements

Candidates will be given a copy of the Periodic Table with the examination paper

11. recall and recognise the chemical symbols for the Group 1 metals (also known as the alkali

metals) lithium, sodium and potassium

12. recall that the alkali metals are shiny when freshly cut but tarnish rapidly in moist air due to

reaction with oxygen

13. use qualitative and quantitative data to identify patterns and make predictions about the

properties of Group 1 metals (for example, melting point, boiling point, density, formulae of

compounds and relative reactivity)

14. describe the reactions of lithium, sodium and potassium with cold water

15. recall that alkali metals react with water to form hydrogen and an alkaline solution of a

hydroxide with the formula MOH

16. recall that alkali metals react vigorously with chlorine to form colourless, crystalline salts with

the formula MCl

17. understand and give examples to show that the alkali metals become more reactive as the

group is descended

18. recall the main hazard symbols and be able to give the safety precautions for handling

hazardous chemicals (limited to explosive, toxic, corrosive, oxidizing, and highly flammable)

19. state and explain the precautions necessary when working with Group 1 metals and alkalis

20. recall and recognise the chemical symbols for the atoms of the Group 7 elements (also

known as the halogens) chlorine, bromine and iodine

21. recall the states of these halogens at room temperature and pressure

22. recall the colours of these halogens in their normal physical state at room temperature and

as gases

23. recall that the halogens consist of diatomic molecules

24. use qualitative and quantitative data to identify patterns and make predictions about the

properties of the Group 7 elements (for example melting point, boiling point, formulae of

compounds and relative reactivity)

25. understand that the halogens become less reactive as the group is descended and give

examples to show this

26. understand how a trend in reactivity for halogens can be shown by their displacement

reactions and by their reactions with alkali metals and with iron

27. state and explain the safety precautions necessary when working with the halogens

28. recall the formulae of:

a. hydrogen, water and halogen (limited to chlorine, bromine and iodine) molecules

b. the chlorides, bromides and iodides (halides) of Group 1 metals (limited to lithium,

sodium and potassium)

29. write word equations for reactions of alkali metals and halogens in this module and for other

reactions when given appropriate information

30. interpret symbol equations, including the number of atoms of each element, the number

of molecules of each element or covalent compound and the number of ‘formulas’ of ionic

compounds, in reactants and products

In this context, ‘formula’ is used in the case of ionic compounds as an equivalent

to molecules in covalent compounds; the concept of the mole is not covered in the

specification

31. balance unbalanced symbol equations

32. write balanced equations, including the state symbols (s), (g), (l ) and (aq), for

reactions of alkali metals and halogens in this module and for other reactions when

given appropriate information

33. recall the state symbols (s), (l ), (g) and (aq) and understand their use in equations.

C4.2 How do chemists explain the patterns in the properties of elements?

1. describe the structure of an atom in terms of protons and neutrons in a very small central

nucleus with electrons arranged in shells around the nucleus

2. recall the relative masses and charges of protons, neutrons and electrons

3. understand that in any atom the number of electrons equals the number of protons

4. understand that all the atoms of the same element have the same number of protons

5. understand that the elements in the Periodic Table are arranged in order of proton number

6. recall that some elements emit distinctive flame colours when heated (for example lithium,

sodium and potassium)

Recall of specific flame colours emitted by these elements is not required

7. understand that the light emitted from a particular element gives a characteristic line

spectrum

8. understand that the study of spectra has helped chemists to discover new elements

9. understand that the discovery of some elements depended on the development of new

practical techniques (for example spectroscopy)

10. use the Periodic Table to work out the number of protons, electrons and neutrons in

an atom

11. use simple conventions, such as 2.8.1 and dots in circles, to represent the electron

arrangements in the atoms of the first 20 elements in the Periodic Table, when the number of

electrons or protons in the atom is given (or can be derived from the Periodic Table)

12. understand that a shell (or energy level) fills with electrons across a period

13. understand that elements in the same group have the same number of electrons in their

outer shell and how this relates to group number

14. understand that the chemical properties of an element are determined by its electron

arrangement, illustrated by the electron configurations of the atoms of elements in

Groups 1 and 7.

C4.3 How do chemists explain the properties of compounds of Group 1 and Group 7

elements?

1. understand that molten compounds of metals with non-metals conduct electricity and that

this is evidence that they are made up of charged particles called ions

2. understand that an ion is an atom (or group of atoms) that has gained or lost electrons and

so has an overall charge

3. account for the charge on the ions of Group 1 and Group 7 elements by comparing the

number and arrangement of the electrons in the atoms and ions of these elements

4. work out the formulae of ionic compounds given the charges on the ions

5. work out the charge on one ion given the formula of a salt and the charge on the other

ion

6. recall that compounds of Group 1 metals with Group 7 elements are ionic

7. understand that solid ionic compounds form crystals because the ions are arranged in a

regular lattice

8. describe what happens to the ions when an ionic crystal melts or dissolves in water

9. explain that ionic compounds conduct electricity when molten or when dissolved in water

because the ions are charged and they are able to move around independently in the liquid.

© OCR 2011 GCSE Science A

The Atmosphere

For students looking at C1 and how the atmosphere has changed throughout history, here are a few useful links from one of the revision websites that we recommend. Some of the words used are a little complicated, and not all the material on the website is part of the course, but it's a good place to get started

Burning Fossil Fuels and Pollution: http://www.docbrown.info/page04/OilProducts04.htm

How the Earth's Atmosphere has Changed (includes carbon cycle): http://www.docbrown.info/page21/GeoChangesANS01.htm

C3 Specification

Module C3: Chemicals in our lives – risks and benefits

C3.1 What were the origins of minerals in Britain that contribute to our economic wealth?

1. understand that geologists explain most of the past history of the surface of the Earth in terms

of processes than can be observed today

2. understand that movements of tectonic plates mean that the parts of ancient continents that

now make up Britain have moved over the surface of the Earth

3. understand how geologists use magnetic clues in rocks to track the very slow movement of

the continents over the surface of the Earth

4. understand that the movements of continents means that different rocks in Britain formed in

different climates

5. understand how processes such as mountain building, erosion, sedimentation, dissolving and

evaporation have led to the formation of valuable resources found in England including coal,

limestone and salt

6. understand how geologists study sedimentary rocks to find evidence of the conditions under

which they were formed, to include:

a. fossils

b. shapes of water borne grains compared to air blown grains

c. presence of shell fragments

d. ripples from sea or river bottom

7. understand that chemical industries grow up where resources are available locally, eg salt,

limestone and coal in north west England.

C3.2 Where does salt come from and why is it so important?

1. understand the importance of salt (sodium chloride) for the food industry, as a source of

chemicals and to treat roads in winter

2. recall that salt can be obtained from the sea or from underground salt deposits

3. understand how underground salt can be obtained by mining, or by solution in water

4. understand why the method used to obtain salt may depend on how the salt is to be used

5. understand how the methods of obtaining salt can have an impact on the environment

6. understand the advantages of adding salt to food as flavouring and as a preservative

7. recall the health implications of eating too much salt

8. be able to evaluate data related to the content of salt in food and health

9. recall that Government departments, such as the Department of Health and the Department

for Environment, Food and Rural Affairs, have a role in:

a. carrying out risk assessments in relation to chemicals in food

b. advising the public in relation to the effect of food on health.

C3.3 Why do we need chemicals such as alkalis and chlorine and how do we make them?

1. recall that, even before industrialisation, alkalis were needed to neutralise acid soils, make

chemicals that bind natural dyes to cloth, convert fats and oils into soap and to manufacture

glass

2. recall that traditional sources of alkali included burnt wood or stale urine

3. understand that alkalis neutralise acids to make salts

4. recall that soluble hydroxides and carbonates are alkalis

5. predict the products of the reactions of soluble hydroxides and carbonates with acids

6. understand that increased industrialisation led to a shortage of alkali in the nineteenth century

7. understand that the first process for manufacturing alkali from salt and limestone using coal

as a fuel caused pollution by releasing large volumes of an acid gas (hydrogen chloride) and

creating great heaps of waste that slowly released a toxic and foul smelling gas (hydrogen

sulfide)

8. understand that pollution problems can sometimes be solved by turning wastes into useful

chemicals

9. understand that oxidation can convert hydrogen chloride to chlorine, and that the properties of

a compound are completely different from the elements from which it is made

10. recall that chlorine is used to kill microorganisms in domestic water supplies and as a bleach

11. understand how the introduction of chlorination to treat drinking water made a major

contribution to public health

12. interpret data about the effects of polluted water on health and the impact of water treatment

with chlorine to control disease

13. understand that there may be disadvantages of chlorinating drinking water, including possible

health problems from traces of chemicals formed by reaction of chlorine with organic materials

in the water

14. understand that an electric current can be used to bring about chemical change and make

new chemicals through a process called electrolysis

15. recall that chlorine is now obtained by the electrolysis of salt solution (brine)

Technical details and the ionic reactions are not required

16. recall examples of important uses by industry of the sodium hydroxide, chlorine and hydrogen

produced by electrolysis of brine

17. interpret data about the environmental impact of the large scale electrolysis of brine.

C3.4 What can we do to make our use of chemicals safe and sustainable?

1. understand that there is a large number of industrial chemicals with many widespread uses,

including consumer products, for which there is inadequate data to judge whether they are

likely to present a risk to the environment and/or human health

2. understand that some toxic chemicals cause problems because they persist in the

environment, can be carried over large distances, and may accumulate in food and human

tissues

3. recall that PVC is a polymer that contains chlorine as well as carbon and hydrogen

4. understand that the plasticizers used to modify the properties of PVC can leach out from the

plastic into the surroundings where they may have harmful effects

5. understand that a Life Cycle Assessment (LCA) involves consideration of the use of resources

including water, the energy input or output, and the environmental impact, of each of these

stages:

a. making the material from natural raw materials

b. making the product from the material

c. using the product

d. disposing of the product

6. when given appropriate information from a Life Cycle Assessment (LCA), compare and

evaluate the use of different materials for the same purpose.

© OCR 2011 GCSE Science A

C2 Specification

Module C2: Material choices

C2.1 How do we measure the properties of materials and why are the results useful?

1. interpret information about how solid materials can differ with respect to properties such as

melting point, strength (in tension or compression), stiffness, hardness and density

2. relate properties to the uses of materials such as plastics, rubbers and fibres

3. relate the effectiveness and durability of a product to the materials used to make it

4. interpret information about the properties of materials such as plastics, rubbers and fibres to

assess the suitability of these materials for particular purposes.

C2.2 Why is crude oil important as a source of new materials such as plastics and fibres?

1. recall that the materials we use are chemicals or mixtures of chemicals, and include metals,

ceramics and polymers

2. recall that materials can be obtained or made from living things, and give examples such as

cotton, paper, silk and wool

3. recall that there are synthetic materials that are alternatives to materials from living things

4. recall that raw materials from the Earth’s crust can be used to make synthetic materials

5. interpret representations of rearrangements of atoms during a chemical reaction

6. understand that in a chemical reaction the numbers of atoms of each element must be the

same in the products as in the reactants

7. recall that crude oil consists mainly of hydrocarbons, which are chain molecules of varying

lengths made from carbon and hydrogen atoms only

8. recall that only a small percentage of crude oil is used for chemical synthesis and that most is

used as fuels

9. understand that the petrochemical industry refines crude oil by fractional distillation;

hydrocarbons are separated into fractions of different boiling points, to produce fuels,

lubricants and the raw materials for chemical synthesis

10. relate the size of the forces between hydrocarbon molecules to the size of the molecules

11. relate the strength of the forces between hydrocarbon molecules in crude oil to the amount

of energy needed for them to break out of a liquid and form a gas, and to the temperature at

which the liquid boils

12. understand that some small molecules called monomers can join together to make very long

molecules called polymers, and that the process is called polymerisation

13. recall two examples of materials that, because of their superior properties, have replaced

materials used in the past.

C2.3 Why does it help to know about the molecular structure of materials such as plastics and fibres?

1. understand that it is possible to produce a wide range of different polymers with properties that

make them each suited to a particular use

2. understand how the properties of polymers depend on how their molecules are arranged and

held together

3. relate the strength of the forces between the molecules in a polymer to the amount of energy

needed to separate them from each other, and therefore to the strength, stiffness, hardness

and melting point of the solid

4. understand how modifications in polymers produce changes to their properties (see C2.1), to

include modifications such as:

a. increased chain length

b. cross-linking

c. the use of plasticizers

d. increased crystallinity.

C2.4 What is nanotechnology and why is it important?

1. recall that nanotechnology involves structures that are about the same size as some

molecules

2. understand that nanotechnology is the use and control of structures that are very small (1 to

100 nanometres in size)

3. understand that nanoparticles can occur naturally (for example in seaspray), by accident (for

example as the smallest particulates from combustion of fuels), and by design

4. understand that nanoparticles of a material show different properties compared to larger

particles of the same material, and that one of the reasons for this is the much larger surface

area of the nanoparticles compared to their volume

5. understand that nanoparticles can be used to modify the properties of materials, and give

examples including:

a. the use of silver nanoparticles to give fibres antibacterial properties

b. adding nanoparticles to plastics for sports equipment to make them stronger

6. understand that some nanoparticles may have harmful effects on health, and that there is

concern that products with nanoparticles are being introduced before these effects have been

fully investigated.

© OCR 2011 GCSE Science A

C1 Specification

Module C2: Air Quality

C1.1 Which chemicals make up air, and which ones are pollutants? How do I make sense of data about air pollution?

1. recall that the atmosphere (air) that surrounds the Earth is made up mainly of nitrogen, oxygen

and argon, plus small amounts of water vapour, carbon dioxide and other gases

2. understand that air is a mixture of different gases consisting of small molecules with large

spaces between them

3. recall that the relative proportions of the main gases in the atmosphere are approximately 78%

nitrogen, 21% oxygen and 1% argon

4. understand that other gases or particulates may be released into the atmosphere by human

activity or by natural processes (eg volcanoes), and that these can affect air quality

5. understand how the Earth’s early atmosphere was probably formed by volcanic activity and

consisted mainly of carbon dioxide and water vapour

6. understand that water vapour condensed to form the oceans when the Earth cooled

7. explain how the evolution of photosynthesising organisms added oxygen to, and removed

carbon dioxide from, the atmosphere

8. explain how carbon dioxide was removed from the atmosphere by dissolving in the oceans

and then forming sedimentary rocks, and by the formation of fossil fuels

9. understand how human activity has changed the composition of the atmosphere by adding:

a. small amounts of carbon monoxide, nitrogen oxides and sulfur dioxide to the

atmosphere

b. extra carbon dioxide and small particles of solids (eg carbon) to the atmosphere

10. understand that some of these substances, called pollutants, are directly harmful to humans

(eg carbon monoxide reduces the amount of oxygen that blood can carry), and that some are

harmful to the environment and so cause harm to humans indirectly (eg sulfur dioxide causes

acid rain).

C1.2 What chemical reactions produce air pollutants? What happens to these pollutants in the atmosphere?

1. recall that coal is mainly carbon

2. recall that petrol, diesel fuel and fuel oil are mainly compounds of hydrogen and carbon

(hydrocarbons)

3. understand that, when fuels burn, atoms of carbon and/or hydrogen from the fuel combine

with atoms of oxygen from the air to produce carbon dioxide and/or water (hydrogen oxide)

4. understand that a substance chemically combining with oxygen is an example of oxidation,

that loss of oxygen is an example of reduction, and that combustion reactions therefore

involve oxidation

5. understand that fuels burn more rapidly in pure oxygen than in air

6. recall that oxygen can be obtained from the atmosphere and can be used to support

combustion (eg in oxy-fuel welding torches)

7. understand that in a chemical reaction the properties of the reactants and products are

different

8. understand that atoms are rearranged during a chemical reaction

9. interpret representations of the rearrangement of atoms during a chemical reaction

10. understand that during the course of a chemical reaction the numbers of atoms of each

element must be the same in the products as in the reactants, thus conserving mass

11. understand how sulfur dioxide is produced if the fuel that is burned contains any sulfur

12. understand how burning fossil fuels in power stations and for transport pollutes the

atmosphere with:

a. carbon dioxide and sulfur dioxide

b. carbon monoxide and particulate carbon (from incomplete burning)

c. nitrogen oxides (from the reaction between atmospheric nitrogen and oxygen at the high

temperatures inside engines)

13. relate the formulae for carbon dioxide CO2, carbon monoxide CO, sulfur dioxide SO2,

nitrogen monoxide NO, nitrogen dioxide NO2 and water H2O to visual representations of their

molecules

14. recall that nitrogen monoxide NO is formed during the combustion of fuels in air, and

is subsequently oxidised to nitrogen dioxide NO2 (NO and NO2 are jointly referred to as

‘NOx’)

15. understand that atmospheric pollutants cannot just disappear, they have to go somewhere:

a. particulate carbon is deposited on surfaces, making them dirty

b. sulfur dioxide and nitrogen dioxide react with water and oxygen to produce acid rain

which is harmful to the environment

c. carbon dioxide is used by plants in photosynthesis

d. carbon dioxide dissolves in rain water and in sea water.

C1.3 What choices can we make personally, locally, nationally or globally to improve air

quality?

1. understand how atmospheric pollution caused by power stations that burn fossil fuels can be

reduced by:

a. using less electricity

b. removing sulfur from natural gas and fuel oil

c. removing sulfur dioxide and particulates from the flue gases emitted by coal-burning

power stations

2. understand how the acid gas sulfur dioxide is removed from flue gases by wet

scrubbing:

a. using an alkaline slurry eg a spray of calcium oxide and water

b. using sea water

Candidates are not required to write word or symbol equations

3. understand that the only way of producing less carbon dioxide is to burn less fossil fuels

4. understand how atmospheric pollution caused by exhaust emissions from motor vehicles can

be reduced by:

a. burning less fuel, for example by having more efficient engines

b. using low sulfur fuels

c. using catalytic converters (in which nitrogen monoxide is reduced to nitrogen by loss of

oxygen, and carbon monoxide is oxidised to carbon dioxide by gain of oxygen)

d. adjusting the balance between public and private transport

e. having legal limits to exhaust emissions (which are enforced by the use of MOT tests)

5. understand the benefits and problems of using alternatives to fossil fuels for motor

vehicles, limited to biofuels and electricity.

© OCR 2011 GCSE Science A

Are 1p coins worth more than 1p?

When talking about C5 and metal purification, a student asked the question: if copper is so expensive, why do we make our lowest value coins from this metal?

The short answer is: we don't.  1p and 2p coins used to be about 97% copper, but as the metal became more expensive, the Royal Mint (the organisation that make the money we use) changed the materials they use to make these coins. Any coppers made after 1992 will be made from copper-plated steel (although in 1998 they did make some 2p coins from the 97% copper blend).

Steel is made with iron, and because iron is magnetic, the new coins should be attracted to a magnet, whereas the old coins will not.

So there you go.

C5 Specification

For classes that are currently studying C5 - Chemicals of the Natural Environment, the specification is below:

C5.1 What types of chemicals make up the atmosphere?

1. recall that dry air consists of gases, some of which are elements (for example, oxygen,

 nitrogen and argon) and some of which are compounds (for example, carbon dioxide)

2. recall that the relative proportions of the main gases in the atmosphere are about 78%

 nitrogen, 21% oxygen, 1% argon and 0.04% carbon dioxide

3. recall the symbols for the atoms and molecules of these gases in the air

4. recall that most non-metal elements and most compounds between non-metal elements are

 molecular

5. understand that molecular elements and compounds with small molecules have low melting

 and boiling points

6. interpret quantitative data (for example, melting and boiling points) and qualitative data about  

the properties of molecular elements and compounds

7. understand that molecular elements and compounds, such as those in the air, have low

melting and boiling points, and are gases at room temperature, because they consist of

small molecules with weak forces of attraction between the molecules

8. understand that pure molecular compounds do not conduct electricity because their

molecules are not charged

9. understand that bonding within molecules is covalent and arises from the electrostatic 

attraction between the nuclei of the atoms and the electrons shared between them

10. understand that covalent bonds are strong, in contrast to the weak forces of attraction

between small covalent molecules

11. translate between representations of molecules including molecular formulae, 2-D diagrams

in which covalent bonds are represented by lines, and 3-D diagrams for:

a. elements that are gases at 20°C

b. simple molecular compounds.

C5.2 What reactions happen in the hydrosphere?

1. recall that the Earth’s hydrosphere (oceans, seas, lakes and rivers) consists mainly of water

with some dissolved compounds, called salts

2. understand that the ions in crystals of a solid ionic compound are arranged in a regular way  

forming a lattice

3. understand that ions in a crystal are held together by forces of attraction between oppositely  

charged ions and that this is called ionic bonding

4. understand how the physical properties of solid ionic compounds (melting point, boiling  

point, electrical conductivity) relate to their bonding and giant, three-dimensional structures 

5. describe what happens to the ions when an ionic crystal dissolves in water

6. explain that ionic compounds conduct electricity when dissolved in water because the ions  

are charged and they are able to move around independently in the solution

7. work out the formulae for salts in seawater given the charges on ions (for example 

sodium chloride, magnesium chloride, magnesium sulfate, sodium sulfate, potassium 

chloride and potassium bromide)

8. understand that the ions in an ionic compound can be detected and identified because they  

have distinct properties and they form compounds with distinct properties

9. understand that an insoluble compound may precipitate on mixing two solutions of ionic  

compounds

10. be able to write ionic equations for precipitation reactions when given appropriate 

information

11. interpret given information on solubility to predict chemicals that precipitate on 

mixing solutions of ionic compounds

12. understand that some metal ions can be identified in solution by adding alkali because they  

form insoluble hydroxides with characteristic colours

13. interpret the results of adding aqueous sodium hydroxide to solutions of salts, given a data  

sheet of tests for positively charged ions and appropriate results

14. understand that some negative ions in salts can be identified in solution by adding a reagent  

that reacts with the ions to form an insoluble solid

15. interpret the results of tests for carbonate, chloride, bromide, iodide and sulfate ions given  

a data sheet of tests for negatively charged ions and appropriate results (using dilute acid,

lime water, silver nitrate and barium chloride or barium nitrate as the reagents).

C5.3 What types of chemicals make up the Earth’s lithosphere?

1. recall that the Earth’s lithosphere (the rigid outer layer of the Earth made up of the crust and  

the part of the mantle just below it) is made up of a mixture of minerals

2. recall that diamond and graphite are minerals, both of which are composed of carbon atoms 

3. explain the properties of diamond in terms of a giant structure of atoms held together by  

strong covalent bonding (for example, melting point, boiling point, hardness, solubility and  

electrical conductivity)

4. understand how the giant structure of graphite differs from that of diamond, and how this  

affects its properties

5. recall that silicon, oxygen and aluminium are very abundant elements in the Earth’s crust 

6. interpret data about the abundances of elements in rocks

7. recall that much of the silicon and oxygen is present in the Earth’s crust as the compound  

silicon dioxide

8. understand that silicon dioxide is another giant covalent compound and so has properties  

similar to diamond.

C5.4 How can we extract useful metals from minerals?

1. recall that ores are rocks that contain varying amounts of minerals from which metals can be  

extracted

2. understand that for some minerals, large amounts of ore need to be mined to recover small  

percentages of valuable minerals (for example, in copper mining)

3. recall that zinc, iron and copper are metals that can be extracted by heating their oxides with  

carbon, and write simple word equations for these reactions

 Technical details not required

4. understand that when a metal oxide loses oxygen it is reduced, while the carbon gains

oxygen and is oxidised

5. understand that some metals are so reactive that their oxides cannot be reduced by carbon

6. write word equations when given appropriate information

7. interpret symbol equations, including the number of atoms of each element, the number  

of molecules of each element or covalent compound and the number of ‘formulas’ of ionic  

compounds, in reactants and products

 In this context, ‘formula’ is used in the case of ionic compounds as an equivalent 

to molecules in covalent compounds; the concept of the mole is not covered in the 

specification

8. balance unbalanced symbol equations

9. write balanced equations, including the state symbols (s), (l ), (g) and (aq), when given 

appropriate information

10. recall the state symbols (s), (l ), (g) and (aq) and understand their use in equations 

11. use the Periodic Table to obtain the relative atomic masses of elements

12. use relative atomic masses to calculate relative formula masses

13. calculate the mass of an element in the gram formula mass of a compound

14. calculate the mass of the metal that can be extracted from a mineral given its formula 

or an equation

15. describe electrolysis as the decomposition of an electrolyte with an electric current

16. understand that electrolytes include molten ionic compounds

17. describe what happens to the ions when an ionic crystal melts

18. understand that, during electrolysis, metals form at the negative electrode and non-metals  

form at the positive electrode

19. describe the extraction of aluminium from aluminium oxide by electrolysis

20. understand that during electrolysis of molten aluminium oxide, positively charged 

aluminium ions gain electrons from the negative electrode to become neutral atoms

21. understand that during electrolysis of molten aluminium oxide, negatively charged 

oxide ions lose electrons to the positive electrode to become neutral atoms which 

then combine to form oxygen molecules

22. use ionic theory to explain the changes taking place during the electrolysis of a 

molten salt to account for the conductivity of the molten salt and the changes at the 

electrodes

23. understand that the uses of metals are related to their properties (limited to strength,  

malleability, melting point and electrical conductivity)

24. explain the physical properties of high strength and high melting point of metals in terms of a

giant structure held together by strong bonds (metallic bonding)

25. understand that in a metal crystal there are positively charged ions, held closely 

together by a sea of electrons that are free to move, and use this to explain the 

physical properties of metals, including malleability and conductivity

26. evaluate, given appropriate information, the impacts on the environment that can arise from  

the extraction, use and disposal of metals.

© OCR 2012 GCSE Additional Science