Electron Transfer in Cells Worksheet

Question 1

Which half reaction releases electrons to the wire?

1. Zn(s) → Zn²⁺(aq) + 2e⁻
2. Cu²⁺(aq) + 2e⁻ → Cu(s)
3. Ag⁺(aq) + e⁻ → Ag(s)
4. Fe³⁺(aq) + e⁻ → Fe²⁺(aq)

Question 2

Explain why an external wire and a salt bridge play different roles in a cell.

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Question 3

Which quantity must match when two half reactions are combined?

1. Electrons released and electrons consumed
2. Number of different metals in each equation
3. Number of solid products in each equation
4. Color of the two solutions

Question 4

In the half reaction Cu²⁺(aq) + 2e⁻ → Cu(s), explain what happens to the copper ions.

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Question 5

In which direction do electrons travel through the wire?

1. From the zinc side to the copper side
2. From the copper side to the zinc side
3. From the salt bridge to both metals
4. From the water to the salt bridge

Question 6

How many Cu²⁺ ions can be reduced when three Zn atoms are oxidized? Show the electron balance.

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Question 7

Which movement helps offset the extra positive charge that appears in the zinc solution?

1. Anions move toward the zinc solution.
2. Cations move toward the zinc solution.
3. Electrons leave the external wire and enter the salt bridge.
4. Zinc nuclei move through the copper metal.

Question 8

Which metal electrode tends to gain mass as the cell runs? Explain using its half reaction.

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