Question

Which of the following is correct expression for solubility product of calcium phosphate?

• A. \(K_{sp}=[\text{Ca}^{2+}]^{2}[\text{PO}_{4}^{3-}]^{2}\)
• B. \(K_{SP}=[\text{Ca}^{3+}]^{2}[\text{PO}_{4}^{2-}]^{3}\)
• C. \(K_{SP}=[\text{Ca}^{2+}]^{2}[\text{PO}_{4}^{2-}]^{3}\)
• D. \(K_{SP}=[\text{Ca}^{2+}]^{3}[\text{PO}_{4}^{3-}]^{2}\)

Hint:

Write the dissociation of Ca3(PO4)2 and raise each ion concentration to its stoichiometric coefficient.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept
The solubility product is the product of ion concentrations, each raised to the power of its coefficient in the dissociation equation.

Step 2: Dissociation
\(\text{Ca}_3(\text{PO}_4)_2\rightleftharpoons3\text{Ca}^{2+}+2\text{PO}_4^{3-}\).

Step 3: Write \(K_{sp}\)
\(K_{sp}=[\text{Ca}^{2+}]^3[\text{PO}_4^{3-}]^2\).

Step 4: Compare the options
This is option (D).

Final Answer:
The solubility product is the cube of the calcium ion concentration times the square of the phosphate ion concentration. \[ \boxed{\text{(D) }K_{sp}=[\text{Ca}^{2+}]^{3}[\text{PO}_{4}^{3-}]^{2}} \]