Question

Question
Which reaction occurs at the anode in a voltaic cell?

Responses

Mg(s)→Mg2++2e−

uppercase M lowercase g open parenthesis lowercase s close parenthesis rightwards arrow uppercase M lowercase g superscript 2 plus end superscript plus 2 lowercase e superscript minus end superscript

K+(aq) + e−→K(s)

uppercase K superscript plus end superscript open parenthesis lowercase a q close parenthesis plus e superscript minus end superscript rightwards arrow uppercase K open parenthesis lowercase s close parenthesis

Cd2+(aq)+Zn(s)→Zn2+(aq)+Cd(s)

uppercase C lowercase d superscript 2 plus end superscript open parenthesis lowercase a q close parenthesis plus uppercase Z lowercase n open parenthesis lowercase s close parenthesis rightwards arrow uppercase Z lowercase n superscript 2 plus end superscript open parenthesis lowercase a q close parenthesis plus uppercase C lowercase d open parenthesis lowercase s close parenthesis

Cu2+(aq)+2e−→Cu(s)

Answer 1

In a voltaic cell (also known as a galvanic cell), oxidation occurs at the anode. This means a species loses electrons at this electrode.

From the provided reactions, we need to identify which one represents the oxidation process (i.e., the loss of electrons).

1. **Mg(s)→Mg2++2e−**
This reaction shows magnesium (Mg) oxidizing; it loses 2 electrons. This reaction occurs at the anode.

2. **K+(aq) + e−→K(s)**
This reaction represents the reduction of potassium, where K+ gains an electron. This occurs at the cathode.

3. **Cd2+(aq)+Zn(s)→Zn2+(aq)+Cd(s)**
This reaction shows zinc oxidizing (losing electrons) while cadmium is reduced (gaining electrons). The half-reaction for Zn would be at the anode.

4. **Cu2+(aq)+2e−→Cu(s)**
This reaction represents the reduction of copper ions (Cu2+) to solid copper, which occurs at the cathode.

The correct answer indicating oxidation occurring at the anode is:

**Mg(s)→Mg2++2e−**