Understanding the Concepts
* Solubility Product (Ksp): The solubility product constant (Ksp) is an equilibrium constant that describes the solubility of a sparingly soluble ionic compound. For AgCl, the Ksp is 1.8 x 10⁻¹⁰.
* Common Ion Effect: The common ion effect describes the decrease in solubility of a sparingly soluble salt when a soluble salt containing a common ion is added to the solution.
Calculations
1. Write the dissolution equilibrium:
AgCl(s) ⇌ Ag⁺(aq) + Cl⁻(aq)
2. Set up an ICE table (Initial, Change, Equilibrium):
| | Ag⁺ | Cl⁻ |
|-------------|-------|--------|
| Initial | 0 | 0.35 | (From NaCl)
| Change | +s | +s |
| Equilibrium | s | 0.35+s |
3. Write the Ksp expression:
Ksp = [Ag⁺][Cl⁻] = 1.8 x 10⁻¹⁰
4. Substitute the equilibrium concentrations into the Ksp expression:
1.8 x 10⁻¹⁰ = (s)(0.35 + s)
5. Since Ksp is very small, we can assume that 's' is negligible compared to 0.35:
1.8 x 10⁻¹⁰ ≈ (s)(0.35)
6. Solve for 's', which represents the solubility of AgCl:
s ≈ (1.8 x 10⁻¹⁰) / 0.35 ≈ 5.1 x 10⁻¹⁰ M
Conclusion
The solubility of AgCl in a 0.35 M NaCl solution is approximately 5.1 x 10⁻¹⁰ M. This value is significantly lower than the solubility of AgCl in pure water, demonstrating the common ion effect.
