The question
Name: ______________________ Date: ____________ Building a nickel-copper galvanic cell (10 points)
Model
A nickel-copper cell
A student builds the galvanic cell shown. Beaker 1 holds a nickel strip in 1.0 M Ni(NO₃)₂(aq); Beaker 2 holds a copper strip in 1.0 M Cu(NO₃)₂(aq). The salt bridge contains KNO₃(aq). The temperature is 25 °C.
| Half-reaction | E° (V) |
|---|---|
| Cu²⁺(aq) + 2e⁻ → Cu(s) | +0.34 |
| Ni²⁺(aq) + 2e⁻ → Ni(s) | −0.25 |
F = 96,485 C/mol e⁻; molar mass of Cu = 63.55 g/mol.
(a) Identify the electrode at which oxidation occurs, and write the half-reaction that occurs there. [1 point]
(b) Write the balanced net ionic equation for the overall reaction in the cell. [1 point]
(c) Calculate the value of E°cell. [1 point]
(d) Calculate the value of ΔG° for the reaction, in kJ/mol. Include the sign. [2 points]
(e) As the cell operates, K⁺ ions move out of the salt bridge. Identify the beaker they move into, and justify your answer. [1 point]
(f) The student repeats the experiment with 0.10 M Cu(NO₃)₂(aq) in Beaker 2, keeping everything else the same. Predict whether the measured cell potential will be greater than, less than or equal to the value in part (c). Justify your prediction. [2 points]
(g) The original cell delivers a steady current of 0.150 A for 2.00 hours. Calculate the mass of copper deposited on the copper electrode. [2 points]