What is the pH of a 0.0067 M KOH solution?

1 Answer
Jun 3, 2016

pH=11.83

Explanation:

Potassium hydroxide fully ionizes when dissolved in water according to the following equation:

KOH -> K^+ + OH^-

Now, let's find the relationship between KOH and OH^-

" " 1 " : "1 " ratio "=> [KOH] =[OH^-]= 6.7xx10^-3M

In any aqueous solution, [H_3O^+] and [OH^-] must satisfy the following condition:

[H_3O^+] [OH^-]= K_w

[H_3O^+] = K_w/([OH^-])

[H_3O^+] = (1.0xx10^-14)/(6.7xx10^-3)

[H_3O^+] = 1.5xx10^-12 M

Now, after finding the concentration of the hydronium ion, the pH of the solution is determined:

pH = -log[H_3O^+]

pH = - log[1.5xx10^-12]

pH=11.83

Other Method
Find the pOH using the concentration of the hydroxide ion, then use the formula " "pH + POH = 14 to find the pH.