8 marksHigher5.3.2.4 Limiting reactants
In a microscale experiment, 0.030 mol aluminium is mixed with 0.030 mol chlorine molecules.
2Al+3Cl2→2AlCl3..1Calculate the amount of aluminium chloride formed.
[3 marks] .2Calculate the amount of aluminium remaining.
[3 marks] .3Explain why doubling only the aluminium would not increase the product amount.
[2 marks] 4 marksHigher5.4.2.5 Strong and weak acids
A sodium hydroxide solution is added gradually to hydrochloric acid. Initially the acid has pH 1; later the mixture has pH 4.
.1Calculate the initial hydrogen ion concentration divided by the later hydrogen ion concentration.
[2 marks] .2Explain the chemical change that removes hydrogen ions. Explain why pH 4 does not show complete neutralisation.
[2 marks] 5 marksFoundation and Higher5.1.2.6 Group 75.1.2.5 Group 1
Chlorine atoms have electron arrangement 2,8,7. Iodine atoms have more occupied electron shells but also seven outer electrons.
.1Explain why chlorine is more reactive than iodine.
[3 marks] .2Compare this trend with the reactivity trend down group 1.
[2 marks] 6 marksHigherRequired practical 085.4.2.2 Neutralisation of acids and salt production5.4.2.3 Soluble salts
Dilute hydrochloric acid is added to excess copper oxide. The black oxide becomes a blue-green copper chloride solution, with black solid remaining.
.1Write the balanced equation.
[2 marks] .2Explain why excess copper oxide is used and how it is removed.
[2 marks] .3Explain why the mass of wet crystals would overestimate the mass of salt recovered.
[2 marks] 4 marksFoundation and Higher5.2.2.5 Polymers
A polymer model contains 150 chains. Each chain contains 400 repeat units.
.1Calculate the total number of repeat units represented.
[2 marks] .2Explain why this model represents a polymer rather than a giant covalent lattice.
[2 marks] 