Question

A chemist dissolves 232 mg of pure sodium hydroxide in enough water to make up of 60 mL solution.
Calculate the pH of the solution. (The temperature of the solution is 25°C.) Round your answer to significant decimal places.

Answer 1

Answer:

pH = 12.985

Explanation:

• NaOH →  Na+  +  OH-

          M           M          M

∴ M NaOH [=] mol NaOH/L sln

∴ mm NaOH = 39.997 g/mol

⇒ mol NaOH = (232 mg NaOH)×(g/1000mg)×(mol/39.997 g) = 5.8 E-3 mol

⇒ M NaOH = 5.8 E-3 mol / 0.06 L = 0.0966 M

⇒  [OH-] = M NaOH = 0.0966 M

∴ pOH = - Log [OH-]

⇒ pOH = - 1.015

⇒ pH = 14 - pOH

⇒ pH = 12.985