Question detail

How can you calculate the cell potential of an electrochemical cell?

Try the question, check the answer, then read the explanation to understand the curriculum point.

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At a glance

MCQ

Type

practice

Style

Topic

Electrode potentials and electrochemical cells (A-level only)

Question

A. By subtracting the standard electrode potential of the anode from that of the cathode.
B. By adding the standard electrode potentials of the two half-cells.
C. By averaging the standard electrode potentials of the two half-cells.
D. By multiplying the standard electrode potentials of the two half-cells.

Answer

By subtracting the standard electrode potential of the anode from that of the cathode.

Explanation

The correct option is By subtracting the standard electrode potential of the anode from that of the cathode.. By subtracting the standard electrode potential of the anode from that of the cathode. is the best answer because it directly supports the AQA A-Level Chemistry objective to predict the feasibility of redox reactions using electrode potentials. This reasoning is anchored to Feasibility and applications of cells (A-level only) in Electrode potentials and electrochemical cells (A-level only), and it separates electrode potential from similar A-Level ideas rather than relying on a vague recall statement. Other options are weaker if they use the wrong evidence, calculation, mechanism, observation, unit, or conclusion for this subtopic.

Common mistake

Misunderstanding Electrode Potential Calculation

Students often confuse the standard electrode potential values and fail to apply the correct signs when calculating cell potentials.

To predict the feasibility of redox reactions using electrode potentials, use the formula: E_cell = E_cathode - E_anode. Substitute the correct standard electrode potentials for the cathode and anode, ensuring to maintain the correct signs. For example, if E_cathode = +0.76 V and E_anode = -0.44 V, then E_cell = 0.76 - (-0.44) = 0.76 + 0.44 = 1.20 V. Thus, the cell potential is 1.20 V, indicating the reaction is feasible. Keep the correction anchored to Feasibility and applications of cells (A-level only) and the objective: Predict the feasibility of redox reactions using electrode potentials.

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