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A galvanic cell has been constructed as shown in the diagram - HSC - SSCE Chemistry - Question 28 - 2060 - Paper 1
Question 28
A galvanic cell has been constructed as shown in the diagram. X metal (anode) Colourless solution 1.0 mol L$^{-1}$ nitrate salt solution of X Cu metal (cathode) B... show full transcript
Worked Solution & Example Answer:A galvanic cell has been constructed as shown in the diagram - HSC - SSCE Chemistry - Question 28 - 2060 - Paper 1
Step 1
Explain the colour change in the copper half-cell as the reaction proceeds.
Answer
As the reaction proceeds, the blue solution in the copper half-cell becomes lighter in color. This color change occurs because copper ions ( ext{Cu}^{2+}) are reduced at the cathode as copper metal is deposited. The decrease in concentration of copper ions in the solution leads to the lighter blue color observed.
Step 2
Identify metal X and justify your answer.
Answer
Metal X is aluminum (Al). This is determined using the standard reduction potentials. Given that the overall standard cell potential is 2.02 V, we can analyze the potential of aluminum used as the anode:
E = E + E
Given E for copper is 0.34 V, we can rearrange:
2.02 V = E + 0.34 V
Thus, E = 2.02 V - 0.34 V = 1.68 V. The standard potential for aluminum is approximately -1.66 V. Therefore, the identification of aluminum is consistent with the calculated standard potentials.