Consider an electrochemical cell based on the spontaneous reaction
2AgCl(s) + Zn(s) $\rarr$ 2Ag(s) + 2Cl^- + Zn²⁺.
If the zinc ion concentration is kept constant at 1 M, and the chlorine ion concentration is decreased from 1 M to 0.001 M, the cell voltage should

Question

Consider an electrochemical cell based on the spontaneous reaction
2AgCl(s) + Zn(s)

\rarr

2Ag(s) + 2Cl^- + Zn²⁺.
If the zinc ion concentration is kept constant at 1 M, and the chlorine ion concentration is decreased from 1 M to 0.001 M, the cell voltage should

Quizplus · Accepted Answer

The cell voltage can be calculated using the Nernst equation:

E = E° - (RT/nF)lnQ

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

At standard conditions (1 M Cl- and Zn2+), the cell voltage is:

E° = E°(cathode) - E°(anode) = 0.80 V - (-0.76 V) = 1.56 V

When the chlorine ion concentration is decreased to 0.001 M, the new reaction quotient is:

Q = (Ag+)2 / (Zn2+)(Cl-)2 = (1/0.001)2 / (1)(0.001)2 = 1 x 106

Plugging in the values to the Nernst equation:

E = 1.56 V - (0.0257 V)ln(1 x 106) = 1.56 V - 0.18 V = 1.38 V

Therefore, the cell voltage increases by 0.18 V when the chlorine ion concentration is decreased from 1 M to 0.001 M.

Consider an Electrochemical Cell Based on the Spontaneous Reaction →\rarr→ 2Ag(s) + 2Cl- + Zn2+

Consider an Electrochemical Cell Based on the Spontaneous Reaction $\rarr$ 2Ag(s) + 2Cl^- + Zn²⁺