# Ap Chemistry

posted by
**Helpplease** on
.

A perchloric acid solution is composed of 168.75 g of perchloric acid and 81.25 mL of pure water. What is the percent by mass of the perchloric acid solution? The density of

water is 1.000 g/mL.

When I did this part I got 67.5%

But, I am having trouble with the secind part.

The density of the above perchloric acid solution is 1.138 g/mL. What is the molarity of the perchloric acid solution?

I know molarity is moles solute/liter of solution, but how do i find that from %mass? please help if you can!! Thanks!