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