Electrochemistry - exam practice

Which is a redox reaction?

The standard reduction potentials of two systems are

Sn⁴⁺_(aq) + 2e^- ⇌ Sn²⁺_(aq) E^⦵ = +0.15 V

Fe³⁺_(aq) + e^- ⇌ Fe²⁺_(aq) E^⦵ = +0.77 V

What is the value of E^⦵_cell for the system below?

Sn⁴⁺_(aq) + 2Fe²⁺_(aq) ➔ Sn²⁺_(aq) + 2Fe³⁺_(aq)

Aluminium is extracted by the electrolysis of a molten mixture containing aluminium oxide.

By a similar method, magnesium is extracted by the electrolysis of a molten mixture containing magnesium chloride.

Which statement about the extraction of magnesium is correct?

A sports medal has a total surface area of 150 cm². It was evenly coated with silver by electrolysis. Its mass increased by 0.216 g.

How many atoms of silver were deposited per cm² on the surface of the medal?

The reaction between acidified dichromate(VI) ions, Cr₂O₇^2-, and aqueous Fe²⁺ ions results in the dichromate(VI) ions being reduced to Cr³⁺ ions.

What is the correct equation for this reaction?

The acid used in a standard hydrogen electrode to provide a 1 mol dm^-3 solution of hydrogen ions is

To measure the standard electrode potential for the Ag⁺_(aq) | Ag_(s) electrode, the most suitable chemical for the solution in a salt bridge to connect the two half cells is

An electrochemical cell consists of a standard hydrogen electrode and a Cu²⁺_(aq) | Cu_(s) electrode which uses copper(II) sulfate solution.

Which one of the following does not affect the e.m.f. of the cell?

The standard electrode potentials of two half reactions are shown below.

$\frac{1}{2}$Cl₂ + e^- ⇌ Cl^- E^⦵ = +1.36 V

Co³⁺ + e^- ⇌ Co²⁺ E^⦵ = +1.82 V

Which of the following processes is thermodynamically favourable? The reaction of

A solution of potassium manganate(VII) was used to determine the concentration of iron(II) ions in solution by titration in the presence of excess dilute sulfuric acid.

With the potassium manganate(VII) in the burette, the end-point of the reaction is when the solution in the conical flask turns

Which of the statements about a standard hydrogen electrode, for which E^⦵ = 0 V, is correct?

The table below gives the standard electrode potentials of three half cells.

From these data it may be deduced that, under standard conditions,

A student is given the electrode potentials below.

Cu²⁺ + 2e^- ⇌ Cu E^⦵ = +0.34 V

Ag⁺ + e^- ⇌ Ag E^⦵ = +0.80 V

The student sets up a cell from the two half cells.

Which statement is correct?

The standard electrode potentials for the aluminium and hydrogen electrodes are:

H⁺_(aq) + e^- ➔ 1⁄2H_2(g) E^⦵ = 0.00 V

Al³⁺_(aq) + 3e^- ➔ Al_(s) E^⦵ = $-$1.66 V

What is formed at the cathode when aqueous aluminium sulfate is electrolysed?

The redox equilibria for a hydrogen-oxygen fuel cell in alkaline solution are shown below.

2H₂O_(l) + 2e^- ⇌ H_2(g) + 2OH^-_(aq) E^⦵ = –0.83 V

$\frac{1}{2}$O_2(g) + H₂O_(l) + 2e^- ⇌ 2OH^-_(aq) E^⦵ = +0.40 V

What is the equation for the overall cell reaction?

The following cell has an e.m.f. of +0.46 V.

Cu | Cu²⁺ || Ag⁺ | Ag

Which statement is correct about the operation of the cell?

The values for two electrodes are shown.

Fe²⁺_(aq) + 2e^- ⇌ Fe_(s) E^⦵ = -0.44 V

Cu²⁺(aq) + 2e^- ⇌ Cu_(s) E^⦵ = +0.34 V

What is the e.m.f. of the cell Fe_(s) | Fe²⁺_(aq) || Cu²⁺_(aq)| Cu_(s)?

Which describes the flow of electrons in a voltaic cell?

Which is not a requirement of the standard hydrogen electrode (SHE)?

Where does oxidation occur in a voltaic cell?

Consider the following half-equations:

I_2(s) + 2e^- ⇌ 2I^-_(aq)

(brown) (colourless)

MnO₄^-_(aq) + 8H⁺_(aq) + 5e^- ⇌ Mn²⁺_(aq) + 4H₂O_(l)

(purple) (colourless)

Which statement is correct for the reaction between KMnO_4(aq) and KI_(aq) in acidic conditions?

A voltaic cell is constructed from zinc and copper half-cells. Zinc is more reactive than copper.

Which statement is correct when this cell produces electricity?

Which statement is correct for a voltaic but not for an electrolytic cell?

What are the products when an aqueous solution of copper(II) sulfate is electrolysed using inert graphite electrodes?

What are the products of the electrolysis of molten zinc bromide?

What are the products of the electrolysis of molten potassium chloride, KCl_(l)?

Which is correct for a redox reaction where the standard electrode potential is negative?

ΔG^⦵ = $-$nFE^⦵ and ΔG^⦵ = $-$RTlnK

Which signs for both E^⦵_cell and ΔG^⦵ result in a spontaneous redox reaction occuring under standard conditions?