How find the pH of this solution? ( Chemistry )

Question

200 mg of KOH are added with H2O until a final volume of 720 ml is reached. Determine the pH of the solution obtained and tell if the solution is acidic or basic.

 

Guys please help me thanks in advanced!

Answer 1

Find [OH-] concentration, then find pOH and finally find the pH

200 mg KOH x 1g/1000 mg x 1 mole/56.1 g = 0.00357 moles

0.00357 moles KOH/0.720 L = 0.00495 M = [OH-]

pOH = -log 0.00495 = 2.31

pH = 14 - pOH = 14 - 2.31 = 11.69 = 11.7

Since the pH is > 7, the solution is basic.