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76 questions
Chemistry/Paper 2/Electrochemistry
CAIEAS Level9701-as · Paper 2

Electrochemistry

76 questions· page 1 of 8

Q2(b)2013 May/Jun·P221MEasy
(b)

The above reaction is an example of a redox reaction.

What are the oxidation numbers of nitrogen in NaNO3\text{NaNO}_3 and in NH3\text{NH}_3?

NaNO3\text{NaNO}_3 ....................... NH3\text{NH}_3 .......................

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Q42011 May/Jun·P222 partsMedium-Easy
(a)(i)

Describe, with the aid of a fully labelled diagram, the industrial electrolysis of brine in a diaphragm cell. State what each electrode is made of and show clearly the inlet for the brine and the outlets for the products.

(a)(ii)

Write a half-equation, with state symbols, for the reaction at each electrode.

anode .......................................................................................................................

cathode ....................................................................................................................

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Q32021 May/Jun·P213 partsMedium
(b)(ii)

The reaction of NaI(s) with concentrated sulfuric acid continues, forming several other products, including a dark grey solid.

Identify the chemical responsible for the dark grey solid and one other product of this further reaction.

  • dark grey solid:
  • other product:
(c)

Explain the differences in observations, at room temperature, when NaI(s) reacts with concentrated sulfuric acid compared to those for NaCl(s).

(d)

Complete the equation for the reaction of Br⁻ with excess concentrated H₂SO₄ at room temperature.

......Br⁻ + ......H⁺ + ......H₂SO₄ → ...............................................................................

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Q22020 May/Jun·P213 partsMedium-Easy
(a)(i)

Balance the equation and include state symbols.

……CuSO4(…… )+……KI(…… )→……CuI(…… )+……I2(…… )+……K2SO4(…… )\dots\dots\text{CuSO}_4(\dots\dots) + \dots\dots\text{KI}(\dots\dots) \rightarrow \dots\dots\text{CuI}(\dots\dots) + \dots\dots\text{I}_2(\dots\dots) + \dots\dots\text{K}_2\text{SO}_4(\dots\dots)
(a)(ii)

The table gives the oxidation numbers of iodine in the different species in the equation.

iodine-containing speciesoxidation number of iodine
KI\text{KI}−1-1
CuI\text{CuI}−1-1
I2\text{I}_200

Deduce the oxidation number of copper in CuSO4\text{CuSO}_4 and CuI\text{CuI}.

  • oxidation number of copper in CuSO4\text{CuSO}_4:
  • oxidation number of copper in CuI\text{CuI}:
(a)(iii)

Describe the type of reaction shown by the equation in (a)(i). Explain your answer in terms of electron transfer.

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Q4(a)(ii)2012 Oct/Nov·P23Easy
(a)(ii)

During some of the reactions in (i) a colour change occurs.

Complete the table below for any such reactions, stating the letter of the reaction and what the colour change is.

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Q2(d)2010 May/Jun·P232MEasy
(d)

When heated in chlorine, all of the alkali metals react to form the corresponding chloride.

Describe what you see when sodium is heated in chlorine and write a balanced equation for the reaction.

description

..........................................................................................................................................

equation

..........................................................................................................................................

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Q22019 May/Jun·P232 partsMedium-Hard
(c)(i)

Write an equation for this reaction.

You may wish to use oxidation numbers to help you.

(c)(ii)

Explain, with reference to oxidation numbers, why this reaction is a redox reaction.

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Q22014 May/Jun·P212 partsEasy
(a)(i)

Explain, in terms of electron transfer, the meaning of the term oxidise in the sentence above.

(a)(ii)

Complete and balance the ionic equation for the reaction between the manganate(VII) ions and the iron(II) ions.

MnO4−(aq)+5Fe2+(aq)+…H+(aq)→…(aq)+5Fe3+(aq)+…H2O(l)\text{MnO}_4^-(\text{aq}) + 5\text{Fe}^{2+}(\text{aq}) + \dots\text{H}^+(\text{aq}) \rightarrow \dots(\text{aq}) + 5\text{Fe}^{3+}(\text{aq}) + \dots\text{H}_2\text{O}(\text{l})
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Q22014 May/Jun·P222 partsEasy
(a)(i)

Explain, in terms of electron transfer, the meaning of the term oxidise in the sentence above.

(a)(ii)

Complete and balance the ionic equation for the reaction between the manganate(VII) ions and the ethanedioate ions.

2MnO4−(aq)+5C2O42−(aq)+……H+(aq)→……(aq)+10CO2(aq)+……H2O(l)2\text{MnO}_4^-(aq) + 5\text{C}_2\text{O}_4^{2-}(aq) + \dots\dots\text{H}^+(aq) \rightarrow \dots\dots(aq) + 10\text{CO}_2(aq) + \dots\dots\text{H}_2\text{O}(l)
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Q12025 Oct/Nov·P223 partsMedium-Easy
(c)(i)

Identify the species that is reduced in half-equation 2. Explain your answer.

(c)(ii)

The oxidation state of carbon in methanal is 0.

Calculate the oxidation state of carbon in carbon dioxide.

(c)(iii)

Construct the ionic equation for the reaction of manganese(IV) oxide with methanal in acidic conditions.

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