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Multiple Choice
The molar solubility of Ba3(PO4)2 is 8.89 × 10^-9 M in pure water. Calculate the Ksp for Ba3(PO4)2.
A
Ksp = 1.05 × 10^-31
B
Ksp = 9.87 × 10^-15
C
Ksp = 2.67 × 10^-18
D
Ksp = 4.44 × 10^-27
Verified step by step guidance
1
Identify the dissolution equation for Ba3(PO4)2 in water: Ba3(PO4)2(s) ⇌ 3Ba^2+(aq) + 2PO4^3-(aq).
Define the molar solubility (s) of Ba3(PO4)2 as 8.89 × 10^-9 M. This represents the concentration of Ba3(PO4)2 that dissolves in water.
Express the concentrations of the ions in terms of s: [Ba^2+] = 3s and [PO4^3-] = 2s, because 3 moles of Ba^2+ and 2 moles of PO4^3- are produced per mole of Ba3(PO4)2.
Write the expression for the solubility product constant (Ksp) using the ion concentrations: Ksp = [Ba^2+]^3 * [PO4^3-]^2.
Substitute the expressions for the ion concentrations in terms of s into the Ksp expression: Ksp = (3s)^3 * (2s)^2. Simplify this expression to find the Ksp value.