A cell Cu|Cu++||Ag+ |Ag initially contains 2M Ag+ and 2M Cu++ ions in ...
Cell Potential Calculation:
To determine the change in cell potential after the passage of current, we need to consider the individual half-cell reactions and their standard cell potentials.
Half-Cell Reactions:
The half-cell reactions involved in this cell are:
Cu2+ + 2e- → Cu (reduction)
Ag → Ag+ + e- (oxidation)
Standard Cell Potentials:
The standard cell potential, E°, for the cell can be calculated using the Nernst equation:
E°cell = E°reduction + E°oxidation
The standard reduction potentials for Cu2+ + 2e- → Cu and Ag → Ag+ + e- are +0.34V and -0.80V, respectively.
Therefore, E°cell = +0.34V + (-0.80V) = -0.46V
Calculating the Change in Cell Potential:
To calculate the change in cell potential after the passage of current, we need to consider the effect of the current on the concentrations of the ions involved in the half-cell reactions.
The passage of current leads to the migration of Cu2+ ions towards the cathode (reduction half-cell) and Ag+ ions towards the anode (oxidation half-cell).
Calculating the Change in Concentration:
The passage of current for a given time can be calculated using Faraday's law:
Q = nF
Where Q is the charge passed (Coulombs), n is the number of electrons transferred in the reaction, and F is the Faraday constant (96,485 C/mol).
Given that the current is 10A and the time is 4825 seconds, the charge passed is:
Q = 10A * 4825s = 48,250 C
Since the number of electrons transferred in the reduction half-cell is 2 (from the balanced equation), the number of moles of Cu2+ ions reduced is:
n = Q / (2F)
n = 48,250 C / (2 * 96,485 C/mol) = 0.25 mol
Similarly, the number of moles of Ag+ ions oxidized is also 0.25 mol.
Calculating the New Concentrations:
The initial concentration of Cu2+ and Ag+ ions is 2M each. After the passage of current, the new concentration can be calculated using the volume of the electrolyte and the number of moles.
Assuming the volume of the electrolyte remains constant at 1L, the new concentration can be calculated as follows:
New concentration = (Number of moles) / (Volume)
New concentration = 0.25 mol / 1 L = 0.25 M
Calculating the New Cell Potential:
Using the Nernst equation, we can calculate the new cell potential, Ecell, with the new concentrations:
Ecell = E°cell - (RT / nF) * ln(Q)
Where R is the gas constant (8.314 J/(mol·K)), T is the temperature in Kelvin, n is the number of electrons transferred, F is the Faraday constant, and Q is the reaction quotient.
Assuming the temperature is 298K, the new cell potential can be calculated as:
Ecell = -0.46
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