Chemistry
posted by Amanda .
Please help me with these! Thanks :)
Describe, in detail, how to make 5.5 liters of a 2.5 molar HCl solution from a 10.5 molar HCl stock solution.
How many grams of a stock solution that is 85.5 percent H2SO4 by mass would be needed to make 150 grams of a 45.0 percent by mass solution? Show all of the work needed to solve this problem.

you are diluting it 10.5/2.5 times, or 4.2 times. Which means, you want one part stock solution, and 3.2 parts water.
well, what is one part? 5.5/4.2=1.31 liters.
Take 1.31 liters of the stock solution (10.5M HCl), then add it to 3.2x1.31=4.19liters water.
always add acid to water.
label the solution.