A-Level AQA Chemistry Electrode Potentials & Electrochemical Cells: This question is about cells.

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Question

This question is about cells.

The half-equations for two electrodes that combine to make a non-rechargeable cell are

Zn	ext{(aq)} + 2e^{-} ightarrow Zn	ext{(s)} \ E^{	ext{o}} = -0.76 	ext{ V}
2MnO_{4}^{-} + 2NH_{4}^{+} + 2e^{-} ightarrow MnO_{2}	ext{(s)} + 2NH_{3}	ext{(aq)} + H_{2}O	ext{(l)} \ E^{	ext{o}} = +0.52 	ext{ V}

Identify the oxidising agent in this cell.

Figure 1 shows a cross-section through a rechargeable silver-zinc cell.

Suggest the function of the porous separator in Figure 1.

The standard electrode potentials for two half-equations for the silver-zinc cell are

Ag^{+}(aq) + H_{2}O	ext{(l)} + 2e^{-} ightarrow 2Ag	ext{(s)} + 2OH^{-}(aq) \ E^{	ext{o}} = +0.34 	ext{ V}
Zn	ext{(s)} + 2H_{2}O	ext{(l)} ightarrow Zn^{2+}(aq) + 2OH^{-}(aq) \ E^{	ext{o}} = -1.26 	ext{ V}

Give an equation for the overall reaction that occurs when the cell is recharging.

The EMF of an alkaline hydrogen–oxygen fuel cell is +1.23 V
The standard electrode potential for one of the electrodes in the alkaline hydrogen–oxygen fuel cell is

2H_{2}(g) + O_{2}(g) + 2e^{-} ightarrow 2OH^{-}(aq) + H_{2} \ E^{	ext{o}} = -0.83 	ext{ V}
Give the half-equation for the other electrode and calculate its standard electrode potential.

Suggest why the EMF values of the acidic and alkaline hydrogen–oxygen fuel cells are the same.

This question is about cells - AQA - A-Level Chemistry - Question 8 - 2022 - Paper 1

Worked Solution & Example Answer:This question is about cells - AQA - A-Level Chemistry - Question 8 - 2022 - Paper 1

Identify the oxidising agent in this cell.

Suggest the function of the porous separator in Figure 1.

Give an equation for the overall reaction that occurs when the cell is recharging.

Give the half-equation for the other electrode and calculate its standard electrode potential.

Suggest why the EMF values of the acidic and alkaline hydrogen–oxygen fuel cells are the same.

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