Final answer:
The molar solubility of calcium hydroxide at a specific pH can be found using the Ksp of Ca(OH)2 and the pH-dependent concentration of H+ or OH- ions. At pH 5, the calculation involves equilibrium expressions that account for the reaction between OH- and H+, while at pH 7, a simpler equilibrium calculation using the Ksp can be performed.
Step-by-step explanation:
The molar solubility of calcium hydroxide can be calculated using the Ksp (solubility product constant) value. The Ksp for calcium hydroxide (Ca(OH)2) is 1.3 × 10-6. To determine the molar solubility, we use the equation:
[Ca2+][OH-] = Ksp
Since calcium hydroxide dissociates into one calcium ion (Ca2+) and two hydroxide ions (OH-), we can substitute the molar solubility of calcium hydroxide as x to get:
x(2x)2 = Ksp
Simplifying this equation gives:
x = sqrt(Ksp/4)
Substituting the Ksp value of 1.3 × 10-6 into the equation gives the molar solubility of calcium hydroxide as approximately 0.0029 M.