Question

Calcium hydroxide, Ca(OH)2, is used as a calcium nutritional supplement in some foods and beverages, such as orange juice. What is the pH of a solution of 0.0012M calcium hydroxide at 25.0∘C?

Answer 1

Answer:

$pH=11.08$

Explanation:

Hello,

In this case, since calcium hydroxide a strong base, its dissociation will completely result in both calcium and hydroxyl ions:

$Ca(OH)_2\rightarrow Ca^{2+}+OH^-$

Thus, the concentration of hydroxyl ions equals that of the calcium hydroxide, with which we could compute the pOH as shown below:

$pOH=-log([OH^-]}=-log(0.0012)\\\\pOH=2.92$

Now, the pH and the pOH are related by:

$pOH+pH=14$

Hence, the pH finally results:

$pH=14-pOH=14-2.92\\pH=11.08$

Best regards.