Question

Hydrogen peroxide is sold as a 3.0% (by mass) solution. The rest of the solution is water . How many grams of hydrogen peroxide are in 250 grams of this solution?

Answer 1

___3% H2O2 (mass/vol) 

a) mass bought = 3g/100ml * 250 ml = ?? g H2O2 

b) moles / 0.250 liter = (?? g H2O2 / MW H2O2 g/mole) / 0.250 liter = ??M 

Plug and SOLVE 

Basic mathematics is a prerequisite to chemistry – I just try to help you with the methodology of solving the problem.