Chemistry
posted by Brittany on .
You wish to prepare 0.18 M HNO3 from a stock solution of nitric acid that is 18.9 M. How many milliliters of the stock solution do you require to make up 1.00 L of 0.18 M HNO3?
Answer and.....
HOW DO I DO IT?

There are a few ways to do these and you may well have a standard formula. However, you might like to try this approach for these problems.
The 1.00 L of 0.18 M HNO3 contains
1.00 L x 0.18 mole L^1 =
0.18 moles of HNO3. So we need 0.18 moles of HNO3 from the stock solution.
so what volume of 18.9 M HNO3 contains
this number of moles?
volume = 0.18 mole/(18.9 mole L^1)
=0.009524 L
or 9.5 ml to 2 sig figs 
I gave you the equation last night and filled in the numbers. All you had to do was to solve for the one unknown, mL of the stock solution. What's the problem?