A student measures the solubility of PbI2 in pure water and in 0.10 M KI by saturating each solvent at 25 C and titrating the I- in the saturated supernatant. In pure water, [I-] = 2.6e-3 M at saturation. In 0.10 M KI, the additional I- from PbI2 dissolution is negligible, and [Pb^2+] is found to be 7.9e-7 M.
What is Ksp of PbI2 from the pure-water trial?
- A
2.6e-3
- B
1.7e-9
- C
6.8e-6
- Dcheck_circle
8.8e-9
Explanation
PbI2 -> Pb^2+ + 2 I-. [Pb^2+] = 1.3e-3, [I-] = 2.6e-3. Ksp = (1.3e-3)(2.6e-3)^2 = 8.8e-9.