Question

The pH of a saturated solution of a metal hydroxide MOH is 10.15. Calculate the Ksp for this compound.

Answer 1

Answer:

$Ksp=2.00x10^{-8}$

Explanation:

Hello!

In this case, since the pH of the given metal is 10.15, we can compute the pOH as shown below:

$pOH=14-pH=14-10.15=3.85$

Now, we compute the concentration of hydroxyl ions in solution:

$[OH^-]=10^{-pOH}=10^{-3.95}=1.41x10^{-4}M$

Now, since this hydroxide has the form MOH, we infer the concentration of OH- equals the concentration of M^+ at equilibrium, assuming the following ionization reaction:

$MOH(s)\rightarrow M^+(aq)+OH^-(aq)$

Whose equilibrium expression is:

$Ksp=[M^+][OH^-]$

Therefore, the Ksp for the saturated solution turns out:

$Ksp=1.41x10^{-4}*1.41x10^{-4}\\\\Ksp=2.00x10^{-8}$

Best regards!