Question 25.4: Consider an electrochemical cell in which the cell reaction ......
Consider an electrochemical cell in which the cell reaction described by the equation
H_{2}(g) + 2\ AgCl(s) ⇋ 2\ Ag(s) + 2\ H^+(aq) + 2\ Cl^−(aq)takes place. In this reaction, H_{2}(g) reduces AgCl(s) to silver metal. Predict the effect of the following changes on the observed cell voltage:
(a) increase in the H_{2}(g) pressure
(b) increase in the concentration of H^+(aq)
(c) increase in the amount of AgCl(s)
Using Le Châtelier’s principle, we predict the following:
(a) An increase in P_{H_{2}} leads to an increase in the concentration of H_{2}(g), and thereby increases the reaction driving force from left to right. The cell voltage thus increases.
(b) An increase in [H^+] increases the reaction driving force from right to left and thus decreases the cell voltage.
(c) An increase in the amount of AgCl(s) has no effect on the cell voltage because a change in the amount of a solid reactant has no effect on the driving force of a reaction and thus no effect on the voltage.