A voltaic cell is constructed with two Zn²⁺-Zn electrodes,where the half-reaction is
Zn²⁺(aq) + 2e^- → Zn(s) E° = -0.763 V
The concentrations of zinc ion in the two compartments are 5.50 M and 1.11 × 10^-² M,respectively.The cell emf is ________ V.

Question

Quizplus · Accepted Answer

The cell emf can be calculated using the Nernst equation:

Ecell = E°cell - (RT/nF)ln(Q)

Where E°cell is the standard cell potential, R is the gas constant, T is the temperature in Kelvin, n is the number of electrons transferred in the balanced equation, F is Faraday's constant, and Q is the reaction quotient.

For this cell, n = 2 because two electrons are transferred in the half-reaction. 
The reaction quotient can be expressed as:

Q = [Zn2+]1/[Zn2+]2

where [Zn2+]1 and [Zn2+]2 are the concentrations of zinc ions in compartments 1 and 2, respectively.

Plugging in the values:

Ecell = -0.763 V - (0.0257 V/K)(298 K)/2(96,485 C/mol)(ln(5.50/1.11×10^12)) 
Ecell = 0.0798 V

Therefore, the answer is C, 0.0798 V.

A Voltaic Cell Is Constructed with Two Zn2+-Zn Electrodes,where the Half-Reaction

A Voltaic Cell Is Constructed with Two Zn²⁺-Zn Electrodes,where the Half-Reaction