NEETChemistryIonic Equilibrium
The solubility product ( K_ sp ) of Fe(OH)₃ is 1.0 10⁻³⁶ . The molar solubility of Fe(OH)₃ in a buffer solution maintained at pH = 10 is:
Options
- A1.0 10⁻³² M
- B1.0 10⁻⁶ M
- C3.3 10⁻²⁵ M
- D1.0 10⁻²⁴ M
Correct answer
D. 1.0 10⁻²⁴ M
Step-by-step solution
In a buffer solution, the pH is fixed, which means the [OH⁻] is also fixed and does not depend on the dissolution of the sparingly soluble salt. Given pH = 10 , we can find the pOH : pOH = 14 - 10 = 4 Therefore, the hydroxide ion concentration is: [OH⁻] = 10⁻⁴ M The dissociation of Fe(OH)₃ is: Fe(OH)₃ Fe³⁺ + 3OH⁻ The solubility product expression is: K_ sp = [Fe³⁺][OH⁻]^3 Let the molar solubility of Fe(OH)₃ in this buffer be s . Then [Fe³⁺] = s . Substitute the fixed [OH⁻] into the expression: 1.0 10⁻³⁶ = (s)(10⁻⁴)