What is the concentration of the NaOH solution?

Question

Suppose you are standardizing a sodium hydroxide solution with KHP (molar mass=204.2 g/mol) according to the equation:

KHP+NaOH⟶H2O+NaKP

You prepare the standard solution from 0.299 g of KHP in 250.0 mL of water. You then require 7.58 mL of NaOH solution to complete the titration. What is the concentration of the NaOH solution?

Answer 1

KHP + NaOH⟶ H2O + NaKP ... balanced equation

0.299 g KHP x 1 mol KHP / 204.2 g = 0.004897 moles

If you titrated the entire 250.0 mls of KHP with NaOH, and it took 7.58 mls of NaOH (0.00758 L), then you can calculate the molar concentration of the NaOH as follows:

0.004897 mols KHP = 0.004897 mols NaOH / 0.00758 L = 0.646 M NaOH (3 sig. figs.)