Electrode Potentials, Cells and Fuel Cells

A standard electrode potential is measured against the standard hydrogen electrode under defined conditions: 298 K, 100 kPa for gases and 1.00 mol dm⁻³ aqueous solutions. Half-equations are conventionally written as reductions. An inert platinum electrode provides an electrical contact where no conducting solid appears in the half-equation. A salt bridge completes the circuit through ionic movement and maintains electrical neutrality; electrons travel through the external wire rather than through the salt bridge.

The half-cell with the more positive standard reduction potential tends to undergo reduction when connected to the other. Calculate $E^\circ_{cell}=E^\circ_{right}-E^\circ_{left}$ for a cell written with reduction on the right, or cathode reduction potential minus anode reduction potential. Multiply half-equations to balance electrons, but do not multiply their electrode potentials. A positive standard cell potential indicates thermodynamic feasibility under standard conditions. Different concentrations, kinetic barriers and passivation can prevent the predicted visible reaction.

A primary cell is used until its reactants are depleted. A rechargeable cell can be driven in reverse by an external electrical supply, within its operating limits. A fuel cell receives fuel and oxidant continuously and produces electricity while those are supplied. Hydrogen–oxygen fuel cells produce water at use, but overall environmental impact includes hydrogen production, compression, transport and catalyst materials. Balance the correct half-equations for the stated acidic or alkaline electrolyte rather than mixing the two conventions.

Attempt these problems on paper before opening the worked reasoning. Explain your steps as well as giving a final answer.