To determine the molarity of NaOH solution, student took 3.5 g of KHP (KHP – Potassium hydrogen phthalate; Molar mass = 204.22 g/mol) and dissolved in 50 mL of water and titrated with the given unknown molarity NaOH solution loaded in burette. His burette volume read 1.85 mL at the start of the experiment and 24.65 mL when the phenolphthalein indicator turned pink.

Answer 1

NaOH + KHP ==> NaKP + H2O

mols KHP = grams/molar mass = ?
mols KHP = mols NaOH (the ratio is 1 mol KHP to 1 mol NaOH in the equation).
M NaOH = mols NaOH/L NaOH = ?
Note: volume NaOH = 24.65 mL - 1.85 mL = ? mL. Convert to L.

Answer 2

0.121 M