What is the pH of a 0.05 M solution of Potassium Hydroxide?
Solution
Potassium Hydroxide or KOH, is a strong base and will dissociate completely in water to K+ and OH-. For every mole of KOH, there will be 1 mole of OH-, so the concentration of OH- will be the same as the concentration of KOH. Therefore, [OH-] = 0.05 M.
Since the concentration of OH- is known, the pOH value is more useful. pOH is calculated by the formula
pOH = - log [OH-]
Enter the concentration found before
pOH = - log (0.05)
pOH = -(-1.3)
pOH = 1.3
The value for pH is needed and the relationship between pH and pOH is given by
pH + pOH = 14
pH = 14 - pOH
pH = 14 - 1.3
pH = 12.7
Answer
The pH of a 0.05 M solution of Potassium Hydroxide is 12.7.
