19.1 Electrochemical Cells

The reaction of copper oxide and sulfuric acid is shown below. Use section 24 of the data booklet to explain why the reaction is thermodynamically feasible.

A student set up a electrolytic cell using a concentrated sodium chloride solution using a current of 6 amps. 

State the half-equations occurring at the electrodes during the electrolysis of the concentrated aqueous solution of sodium chloride.

Cathode ..................................................................................................

Anode ....................................................................................................

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Use section 2 of the data booklet to determine the time, in minutes, to produce 2.00 dm³ of gas at the anode at standard temperature and pressure. State your answer to 2 significant figures. 

The student changed the electrolyte to a very dilute sodium chloride solution. State what change would occur at the anode and give the half equation for the process.

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In a different electrolysis experiment, copper sulfate solution was electrolysed using graphite electrodes. Using section 24 of the data booklet explain how the products at the anode and cathode are produced. 

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The standard electrode potential for Zn²⁺ (aq) + 2e^- → Zn (s) is –0.76 V. State the meaning of the minus sign in the value of –0.76 V.

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Complete the diagram by labelling the polarity of the power source by using a + and - sign. 

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Use sections 2 and 6 of the data booklet to determine the length of time, in hours, a 0.1 A current required to deposit 1.0 g of zinc on the item to be electroplated. State your answer to 2 significant figures. 

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Using section 24 of the data booklet deduce the full equation for the Cr₂O₇^2- (aq) / Cr³⁺ (aq) and Br₂ (l) / Br^- (aq) cell.

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Determine the value for E^Θcell value for the cell outlined in part a). 

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Use your answer to part b) and sections 1 and 2 of the data booklet to determine whether the reaction in part a) reaction is spontaneous.

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An electrochemical cell has a free energy change of -144.75 kJ mol^-1. Use the information in the table to determine the cell representation of the electrochemical cell. 

Electrode half-equation	EӨ / V
Ag+ (aq) + e- ⇌ Ag (s)	+0.80
Li+ (aq) + e- ⇌ Li (s)	-3.04
ClO2 (aq) + e- ⇌ ClO2- (aq)	+0.95
H2O (l) + e- ⇌ ½H2 (g) + OH- (aq)	-0.83
Fe3+ (aq) + e- ⇌ Fe2+ (aq)	+0.77

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