An aqueous solution of Ca(OH)2 has an equilibrium calcium ion concentration of [Ca2+] = 6.33×10−3 M at 25 oC.
What is the pH of the solution?
Ca(OH)2(s) ==> Ca^2+ + 2OH^-
If (Ca^2+) = 6.33E-3 the OH must be twice that. Convert that to pH.
To find the pH of the solution, we need to determine the concentration of hydroxide ions (OH-) first.
Given that the concentration of calcium ions (Ca2+) is 6.33×10−3 M, we can assume that an equal number of hydroxide ions are produced since the chemical formula for calcium hydroxide is Ca(OH)2. Therefore, the concentration of hydroxide ions (OH-) is also 6.33×10−3 M.
The pH of a solution can be calculated using the formula:
pOH = -log[OH-]
Since pOH + pH = 14 (at 25 oC), we can calculate the pH:
pH = 14 - pOH
Now, substituting the concentration of hydroxide ions into the formula:
pOH = -log(6.33×10−3)
Using a calculator, the pOH is approximately 2.2.
Substituting the pOH value into the pH formula:
pH = 14 - 2.2
The pH of the solution is approximately 11.8.