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Practice Problem 7.5

Calculate the solubility of silver acetate, [tex]CH_3COOAg[/tex], in [tex]mol/dm^3[/tex], given the [tex]K_{sp}[/tex] value for silver acetate, [tex]CH_3COOAg[/tex], is [tex]K_{sp} = 1.9 \times 10^{-3}[/tex].



Answer :

To calculate the solubility of silver acetate ([tex]$CH_3COOAg$[/tex]) in mol/dm[tex]\(^3\)[/tex] given the solubility product constant ([tex]\(K_{sp}\)[/tex]) of [tex]\(1.9 \times 10^{-3}\)[/tex], we can follow these steps:

### Step-by-Step Solution:
1. Write the Dissociation Equation:
[tex]\[ CH_3COOAg (s) \leftrightarrow CH_3COO^- (aq) + Ag^+ (aq) \][/tex]

2. Write the Solubility Product Expression ([tex]\(K_{sp}\)[/tex]):
- The solubility product constant is defined as the product of the molar concentrations of the constituent ions, each raised to the power of their coefficients in the balanced equation.
[tex]\[ K_{sp} = [CH_3COO^-][Ag^+] \][/tex]

3. Express Concentrations in Terms of Solubility (S):
- Let [tex]\(S\)[/tex] be the solubility of [tex]\(CH_3COOAg\)[/tex] in mol/L (or mol/dm[tex]\(^3\)[/tex]). Since one mole of [tex]\(CH_3COOAg\)[/tex] dissociates into one mole of [tex]\(CH_3COO^-\)[/tex] and one mole of [tex]\(Ag^+\)[/tex], the concentrations of both ions in the solution will be equal to [tex]\(S\)[/tex]:
[tex]\[ [CH_3COO^-] = S \quad \text{and} \quad [Ag^+] = S \][/tex]

4. Substitute These Concentrations into the [tex]\(K_{sp}\)[/tex] Expression:
[tex]\[ K_{sp} = S \times S = S^2 \][/tex]
- Given [tex]\(K_{sp} = 1.9 \times 10^{-3}\)[/tex]:
[tex]\[ 1.9 \times 10^{-3} = S^2 \][/tex]

5. Solve for [tex]\(S\)[/tex]:
- Take the square root of both sides to find [tex]\(S\)[/tex]:
[tex]\[ S = \sqrt{1.9 \times 10^{-3}} \][/tex]

By calculating the square root of [tex]\(1.9 \times 10^{-3}\)[/tex], we find that the solubility [tex]\(S\)[/tex] is approximately:

[tex]\[ S \approx 0.0436 \, \text{mol/dm}^3 \][/tex]

Therefore, the solubility of silver acetate, [tex]\(CH_3COOAg\)[/tex], in mol/dm[tex]\(^3\)[/tex] is [tex]\(\boxed{0.0436}\)[/tex].