Question

What is the molarity (M) of a NaOH solution if 22.47 mL are needed to titrate a 0.3819 g sample of KHP?

Answer 1

KHP = Potassium hydrogen phthalate = KHC8H4O4

Reaction :- KHC8H4O4 (aq) + NaOH (aq) -----> NaKC8H4O4(aq) + H2O (l)

Mass of KHP = 0.3819 g, Molar mass of KHP = 204.22 g/mol

Number of moles = mass in gram / Molar mass

Number of moles of KHP = 0.3819 g / 204.22 g/mol = 0.00187 mol

From reaction, 1.0 mol of NaOH reacts with 1.0 mol of KHP so 0.00187 mol of KHP will react with 0.00187 mol of NaOH.

Volume of NaOH solution = 22.47 ml = 22.47 L / 1000 = 0.02247 L

Molarity = number of moles / Volume of solution in Litre

Molarity of NaOH = 0.00187 mol / 0.02247 L = 0.083 mol/L = 0.083 M

Molarity of NaOH solution = 0.083 M