Suppose the reaction Pb(s) + 2H⁺(aq) $\rarr$ Pb²⁺(aq) + H₂(g) is carried out at pH = 4.00 and at a hydrogen gas pressure of 1.00 atm. The concentration of lead(II) ions that causes this reaction to be at equilibrium is

Question

Quizplus · Accepted Answer

The equilibrium constant expression for the reaction is:

K = [PbS][H2S]/(Pb[H2S2])

At equilibrium, K = 4.0 × 10^13 (from the given data)

[H2S] = [HS^-] because of the pH value

[PbS] = x (let the concentration of PbS be x)

[Pb] = x (because the stoichiometric coefficient of Pb in the balanced equation is 1)

[H2S2] = P(H2S) = 1 atm

Substituting these values in the K expression, we get:

4.0 × 10^13 = [x][HS^-]/(x)

[S2-] can be neglected in the equilibrium expression because it is much less compared to [HS^-]

Simplifying the above equation, we get:

[HS^-] = 4.0 × 10^13 M

At equilibrium, [HS^-] = [H+] because of the pH value

Therefore, [Pb] = x = [HS^-] = [H+] = 2.5 × 10^-4 M

The correct choice is C.

Suppose the Reaction Pb(s) + 2H+(aq) →\rarr→ Pb2+(aq) + H2(g) Is Carried Out at PH = 4

Suppose the Reaction Pb(s) + 2H⁺(aq) $\rarr$ Pb²⁺(aq) + H₂(g) Is Carried Out at PH = 4