Question

Calculate the volume of 50 % by mass NaOH needed to prepare 1.0L of 0.1 M NaOH solution.

Answer 1

Molarity of the solution = 0.1 M

Volume of solution = 1.0 L

50 % by mass NaOH means:

50 g NaOH present in 100 g of the solution.

500 g NaOH will be present in 1000 g solution.

Molar mass of NaOH = 39.997 g/mole

Moles of NaOH = Mass / Molar mass

= 500 / 39.997

= 12.5 moles

Volume of 1000 g solution = 1 L

Molarity of solution = 12.5 / 1 = 12.5 M

Now,

This NaOH solution is used to prepare 1.0L of 0.1 M NaOH solution.

Let volume V is required to prepare the solution.

M1V1 = M2V2

12.5 * V1 = 1.0 * 0.1

12.5 * V1 = 0.1

V1 = 0.1 / 12.5

V1 = 0.008 L

= 8 mL

Hence,

The volume required is 8 mL