Question detail
What is the cell potential of an electrochemical cell if the standard electrode potentials are +0.76 V and -0.34 V?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Electrode potentials and electrochemical cells (A-level only)
Question
- A. +1.10 V
- B. +0.42 V
- C. -0.42 V
- D. -1.10 V
Answer
+1.10 V
Explanation
The correct option is +1.10 V. +1.10 V is the best answer because it directly supports the AQA A-Level Chemistry objective to required practical: measure the EMF of an electrochemical cell. This reasoning is anchored to Standard electrode potentials (A-level only) in Electrode potentials and electrochemical cells (A-level only), and it separates electrochemical cell 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
Measuring EMF of Electrochemical Cells
Students often forget to account for the correct polarity when measuring the EMF of an electrochemical cell, leading to incorrect potential values.
To fix this, remember to connect the positive terminal of the voltmeter to the more positive electrode and the negative terminal to the more negative electrode. Use the formula for EMF: EMF = E(cathode) - E(anode). Substitute the standard electrode potentials for the cathode and anode, calculate the difference, and ensure the final answer is expressed in volts (V). Keep the correction anchored to Standard electrode potentials (A-level only) and the objective: Required practical: measure the EMF of an electrochemical cell.
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