Describe how are you going to prepare 100 mL 3% (by mass) H2O2 solution from 20% to 40% H2O2 solution

Question

Concentration needed: 3%

Volume needed: 100 mL

Concentration available: 20% to 40%

Please state a complete detailed solution. Kindly help me asap because it's so difficult

Answer 1

Calculations:

Unless you happen to know the density of the different solutions, the following procedure would be on approach to preparing the desired solution.

3% by mass H2O2 means 3 g H2O2 / 100 g solution

So to make 100 mls of this solution, you will require 3 g of H2O2

How to get 3 g of H2O2 from 20% (20 g / 100 g solution) H2O2?

3 g H2O2 x 100 g / 20 g = 15 g of the 20% solution

Procedure:

Weigh out 15 g of the 20% H2O2 solution

Add sufficient water to make the final mass 100 g