AI SearchTopicalsYearlysNotesDashboardPricing
9701/43

Chemistry 9701/43 — May/June 2013

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

8
questions
100
marks
120
minutes

Topics Carboxylic Acids and Derivatives · Hydroxy Compounds · Polymerisation · Electrochemistry · Equilibria · Reaction Kinetics · +5 more

Q1ElectrochemistryEquilibriaFree sample

Section A

Answer all the questions in the spaces provided.

(a)

What is meant by the term standard electrode potential, SEP?

2M
(b)

Draw a fully labelled diagram of the apparatus you could use to measure the SEP of the Fe3+/Fe2+\text{Fe}^{3+} / \text{Fe}^{2+} electrode.

5M
(c)

The reaction between Fe3+\text{Fe}^{3+} ions and I−\text{I}^- ions is an equilibrium reaction.

2Fe3+(aq)+2I−(aq)⇌2Fe2+(aq)+I2(aq)2\text{Fe}^{3+}(\text{aq}) + 2\text{I}^-(\text{aq}) \rightleftharpoons 2\text{Fe}^{2+}(\text{aq}) + \text{I}_2(\text{aq})
8M
(i)

Use the Data Booklet to calculate the Ecell⊖E^\ominus_{\text{cell}} for this reaction.

(ii)

Hence state, with a reason, whether there will be more products or more reactants at equilibrium.

(iii)

Write the expression for KcK_c for this reaction, and state its units.

Kc=K_c =

(iv)

An experiment was carried out using solutions of Fe3+(aq)\text{Fe}^{3+}(\text{aq}) and I−(aq)\text{I}^-(\text{aq}) of equal concentrations. 100 cm3100\text{ cm}^3 of each solution were mixed together, and allowed to reach equilibrium.

The concentrations at equilibrium of Fe3+(aq)\text{Fe}^{3+}(\text{aq}) and I2(aq)\text{I}_2(\text{aq}) were as follows.

[Fe3+(aq)]=2.0×10−4 mol dm−3[I2(aq)]=1.0×10−2 mol dm−3\begin{aligned} [\text{Fe}^{3+}(\text{aq})] &= 2.0 \times 10^{-4}\text{ mol dm}^{-3} \\ [\text{I}_2(\text{aq})] &= 1.0 \times 10^{-2}\text{ mol dm}^{-3} \end{aligned}

Use these data, together with the equation given in (c), to calculate the concentrations of Fe2+(aq)\text{Fe}^{2+}(\text{aq}) and I−(aq)\text{I}^-(\text{aq}) at equilibrium.

[Fe2+(aq)]=[\text{Fe}^{2+}(\text{aq})] = ............................... mol dm−3\text{mol dm}^{-3}

[I−(aq)]=[\text{I}^-(\text{aq})] = ............................... mol dm−3\text{mol dm}^{-3}

(v)

Calculate the KcK_c for this reaction.

Kc=K_c =

The rest of this paper

7 more questions
  • Q2Reaction Kinetics9M
  • Q3Transition Elements14M
  • Q4Nitrogen Compounds · Halogen Compounds · Carboxylic Acids and Derivatives15M
  • Q5Carboxylic Acids and Derivatives · Hydrocarbons · Hydroxy Compounds17M
  • Q6Polymerisation10M
  • Q7Analytical Techniques10M
  • Q8Polymerisation · Hydroxy Compounds10M
Loading the full paper…