Hair bleaching solutions contain hydrogen peroxide, H2O2. The amount of hydrogen peroxid...

Hair bleaching solutions contain hydrogen peroxide, H₂O₂. The amount of hydrogen peroxide in the solution can be determined by making H₂O₂ react with an acidic solution of potassium dichromate. The unbalanced equation for the reaction is

A 30.00-g sample of the bleach solution needed 75.8 mL of 0.388 M K₂Cr₂O₇ to react completely with the bleach. Assuming no other compounds that react with K₂Cr₂O₇ are in the solution, what is the mass percent of H₂O₂ in the bleach?