Chemistry 9701 · AS & A Level · Equilibria

Equilibria — practice question

Silver carbonate, $\text{Ag}_2\text{CO}_3$, is only slightly soluble in water. Its solubility product constant, $K_{sp}$, is $6.3 \times 10^{-12}$ at $25^\circ\text{C}$.
(a(i))[2]

State an expression for the solubility product, $K_{sp}$, of $\text{Ag}_2\text{CO}_3$, and give its units.

(a(ii))[1]

Calculate the equilibrium concentration of $\text{Ag}^+$ in a saturated $\text{Ag}_2\text{CO}_3$ solution at $25^\circ\text{C}$.

(a(iii))[1]

A sample of solid $\text{Ag}_2\text{CO}_3$ is shaken at $25^\circ\text{C}$ with $0.050\ \text{mol dm}^{-3}$ $\text{AgNO}_3$ until no further $\text{Ag}_2\text{CO}_3$ dissolves. Calculate the carbonate ion concentration, $[\text{CO}_3^{2-}]$, in this solution.

(a(iv))[2]

An electrochemical cell is used to determine the electrode potential, $E$, of the $\text{Ag}^+/\text{Ag}$ half-cell by pairing saturated $\text{Ag}_2\text{CO}_3(\text{aq})$ with a standard hydrogen electrode. Use the Data Booklet, your result from (a)(ii), and the Nernst equation to find the electrode potential, $E$, for this $\text{Ag}^+/\text{Ag}$ half-cell.

(b(i))[1]

Calculate the standard entropy change of solution, $\Delta S^\circ$, for $\text{AgCl}(s) \rightarrow \text{Ag}^+(aq) + \text{Cl}^-(aq)$, given that $\Delta H^\circ_{sol} = +65.5\ \text{kJ mol}^{-1}$.

(b(ii))[3]

Explain, with the help of a calculation, why $\text{AgCl}$ does not dissolve in water at $25^\circ\text{C}$. You should use data from this question and your answer to (b)(i).

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: $K_{sp} = [Ag^+]^2[CO_3^{2-}]$

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI