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A galvanic cell was made by connecting two half-cells - HSC - SSCE Chemistry - Question 18 - 2001 - Paper 1
Question 18
A galvanic cell was made by connecting two half-cells. One half-cell was made by putting a copper electrode in a copper (II) nitrate solution. The other half-cell wa... show full transcript
Worked Solution & Example Answer:A galvanic cell was made by connecting two half-cells - HSC - SSCE Chemistry - Question 18 - 2001 - Paper 1
Step 1
Complete the above diagram by drawing a salt bridge.
Answer
A salt bridge can be illustrated as a tube connecting the two solutions, typically filled with a gel or solution containing an electrolyte such as potassium nitrate. This allows ions to flow between the half-cells, maintaining electrical neutrality.
Step 2
Using the standard potentials table in the data sheet, calculate the theoretical voltage of this galvanic cell.
Answer
The theoretical voltage (E°) of the galvanic cell can be calculated using the standard electrode potentials of the reactions occurring at the electrodes.
For the copper half-cell:
- Reduction: Cu^{2+} + 2e^{-} → Cu(s) E° = +0.34 V
For the silver half-cell:
- Reduction: Ag^{+} + e^{-} → Ag(s) E° = +0.80 V
The overall cell voltage is given by: The cathode (reduction) is Ag, and the anode (oxidation) is Cu. Thus,
Therefore, the theoretical voltage of the galvanic cell is 0.46 V.
Step 3
Explain, using an equation, why the copper electrode will increase in mass.
Answer
The increase in mass of the copper electrode can be explained by the electrochemical reaction occurring at the electrode. When the generator is introduced into the circuit, it drives the oxidation of the copper ions, causing copper to be deposited onto the electrode. The equation for the reduction reaction at the copper electrode can be represented as:
This indicates that copper ions from the solution gain electrons and are reduced to solid copper, which deposits onto the electrode, thus increasing its mass.