Question

In the figure below, which electrodes are negative terminals? I have worked out that E: Cu2+ -> Cu, F: OH- -> O2, G: H+ -> H2, H: OH- -> O2. However, I am still confused about the polarity of the electrodes and I have thought of two explanations

By definition, electron flows out of the negative terminal, so E and F are negative terminals
In an electrolytic cell, the negative terminal is the cathode. So E and G are negative terminals
Which one is correct?

Answer 1

In an electrochemical cell, the electrode where reduction occurs and electrons are gained is called the cathode. The electrode where oxidation occurs and electrons are lost is called the anode. Based on the given reactions, E and F are the negative terminals.

Step-by-step explanation:

In an electrochemical cell, the electrode where reduction occurs and electrons are gained is called the cathode. The electrode where oxidation occurs and electrons are lost is called the anode. Electrons will always move from the anode to the cathode. The electrode that functions as the cathode is considered the negative terminal.

Based on the information you have provided, you correctly identified E: Cu2+ → Cu and F: OH- → O2 as reduction reactions, which means they occur at the cathode. Therefore, E and F are the negative terminals in the figure.

So, the explanation that states electron flows out of the negative terminal and E and F are negative terminals is correct.