Energy

EasyMediumHard
1234567891011121314151617181920212223242526272829303132333435363738394041
Question 8
Medium

Four redox systems relevant to hydrogen–oxygen fuel cells are shown below:

SystemHalf-equationE∘ / V1H2O(l)+e−⇌OH−(aq)+12H2(g)−0.832H+(aq)+e−⇌12H2(g)+0.00312O2(g)+H2O(l)+2e−⇌2OH−(aq)+0.40412O2(g)+2H+(aq)+2e−⇌H2O(l)+1.23 \begin{array}{|c|c|c|} \hline \text{System} & \text{Half-equation} & E^\circ \text{ / V} \\ \hline \text{1} & \text{H}_2\text{O(l)} + \text{e}^- \rightleftharpoons \text{OH}^-\text{(aq)} + \frac{1}{2}\text{H}_2\text{(g)} & -0.83 \\ \hline \text{2} & \text{H}^+\text{(aq)} + \text{e}^- \rightleftharpoons \frac{1}{2}\text{H}_2\text{(g)} & \phantom{+}0.00 \\ \hline \text{3} & \frac{1}{2}\text{O}_2\text{(g)} + \text{H}_2\text{O(l)} + 2\text{e}^- \rightleftharpoons 2\text{OH}^-\text{(aq)} & +0.40 \\ \hline \text{4} & \frac{1}{2}\text{O}_2\text{(g)} + 2\text{H}^+\text{(aq)} + 2\text{e}^- \rightleftharpoons \text{H}_2\text{O(l)} & +1.23 \\ \hline \end{array} System1234​Half-equationH2​O(l)+e−⇌OH−(aq)+21​H2​(g)H+(aq)+e−⇌21​H2​(g)21​O2​(g)+H2​O(l)+2e−⇌2OH−(aq)21​O2​(g)+2H+(aq)+2e−⇌H2​O(l)​E∘ / V−0.83+0.00+0.40+1.23​​

Which statement(s) is/are correct for an alkaline hydrogen–oxygen fuel cell?

  1. The reaction at the negative electrode is: H2(g)+2OH−(aq)→2H2O(l)+2e−\text{H}_2\text{(g)} + 2\text{OH}^-\text{(aq)} \rightarrow 2\text{H}_2\text{O(l)} + 2\text{e}^-H2​(g)+2OH−(aq)→2H2​O(l)+2e−.
  2. The standard cell potential is 1.23 V.
  3. Water is a reactant in the overall cell reaction.

1, 2 and 3

Only 1 and 2

Only 2 and 3

Only 1

Energy Questions

  1. A Level
  2. /Chemistry
  3. /Energy