Chemistry 9701/42 — May/June 2017

Cambridge A-Level · A Level Structured Questions · worked solutions for every part, with the mark scheme

questions

100

marks

120

minutes

Topics Introduction to A Level Organic Chemistry · Halogen Compounds · Carboxylic Acids and Derivatives · Nitrogen Compounds · Chemical Energetics · Transition Elements · +6 more

Q1Group 2Chemical EnergeticsFree sample

(a)

(i)

Describe and explain the variation in the thermal stabilities of the carbonates of the Group 2 elements.

(ii)

Suggest and explain a reason why sodium carbonate is more stable to heat than magnesium carbonate.

(b)

Sodium hydrogencarbonate, $\text{NaHCO}_3$ , and potassium hydrogencarbonate, $\text{KHCO}_3$ , decompose on heating to produce gases and the solid metal carbonate.

(i)

Write an equation for the decomposition of $\text{KHCO}_3$ .

(ii)

Predict which of $\text{NaHCO}_3$ or $\text{KHCO}_3$ will decompose at the lower temperature. Explain your answer.

(c)

(i)

Use the data in the table below, and relevant data from the Data Booklet, to calculate the lattice energy, $\Delta H^\ominus_{\text{latt}}$ , of potassium oxide, $\text{K}_2\text{O}(\text{s})$ .

energy change	value / $\text{kJ mol}^{-1}$
enthalpy change of atomisation of potassium, $\Delta H^\ominus_{\text{at}}$ K(s)	+89
electron affinity of O(g)	-141
electron affinity of $\text{O}^-$ (g)	+798
enthalpy change of formation of potassium oxide, $\Delta H^\ominus_{\text{f}}$ $\text{K}_2\text{O}(\text{s})$	-361

(ii)

State whether the lattice energy of $\text{Na}_2\text{O}$ would be more negative, less negative or the same as that of $\text{K}_2\text{O}$ . Give reasons for your answer.

The rest of this paper

7 more questions

Q2Halogen Compounds · Reaction Kinetics · Introduction to A Level Organic Chemistry · Analytical Techniques18M
Q3Carboxylic Acids and Derivatives · Nitrogen Compounds · Introduction to A Level Organic Chemistry14M
Q4Transition Elements6M
Q5Transition Elements · Chemical Energetics17M
Q6Equilibria · Carboxylic Acids and Derivatives · Nitrogen Compounds10M
Q7Introduction to A Level Organic Chemistry · Hydrocarbons · Halogen Compounds · Hydroxy Compounds · Carboxylic Acids and Derivatives10M
Q8Introduction to A Level Organic Chemistry · Halogen Compounds · Nitrogen Compounds15M

Loading the full paper…