Question:medium

The solubility CaF\(_2\) is s moles/litre. Then solubility product is

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For AB\(_2\) type salts, \(K_{sp} = 4s^3\).
Updated On: Jun 16, 2026
  • \(s^2\)
  • \(4s^3\)
  • \(3s^2\)
  • \(s^3\)
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The Correct Option is B

Solution and Explanation

To determine the solubility product (\(K_{sp}\)) of calcium fluoride (CaF\(_2\)), we must first consider its dissociation in water. The dissociation equation for CaF\(_2\) is as follows:

\(\text{CaF}_2 (s) \leftrightarrow \text{Ca}^{2+} (aq) + 2\text{F}^- (aq)\)

Given that the solubility of CaF\(_2\) is \(s\) moles per liter, this indicates the concentration of CaF\(_2\) that dissolves to reach the equilibrium. Therefore, at equilibrium:

  • The concentration of Ca\(^{2+}\) ions = \(s\) moles/liter
  • The concentration of F\(^-\) ions = \(2s\) moles/liter

The solubility product (\(K_{sp}\)) expression for CaF\(_2\) is:

\(K_{sp} = [\text{Ca}^{2+}][\text{F}^-]^2\)

Substituting the equilibrium concentrations into the solubility product expression:

\(K_{sp} = (s)(2s)^2\)

Simplifying the expression:

\(K_{sp} = s \cdot 4s^2 = 4s^3\)

Thus, the solubility product of CaF\(_2\) is \(4s^3\).

Therefore, the correct answer is \(4s^3\).

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