posted by jimmy .
how many grams of a stock solution that is 85% H2SO4 by mass would be needed to make 150 grams of a 45.0 percent solution?
you want to dilute it 85/45= 1.889 times?
That means one part acid, .889 parts water.
So what is one part? 150/1.889=about 79grams acid, about 70.2g water.