ok, so i have to find the mass of the HNO3 in 1 L and the mass of the H2O in 1 L.

I'm given:
HNO3 solution
1.42 g/mL
16M
I'm really terrible at this stuff and it should be easy, but I have no idea where to start.

2 answers

16 M means 16 mols HNO3/L of solution.
How much is 16 moles HNO3? 1 mole = approximately 63 grams (1+14+48=about 63) so 16 moles would be 16 x 63 grams in 1 L.
How much does 1 L of the solution weigh? It has a density of 1.43 g/mL; therefore, 1000 mL is
1000 x 1.42 g/mL = 1420 grams.
How much of that is HNO3. From above.
Then mass water = 1420 g - mass HNO3.
ok, sweet. i had most of that set up right.
so the mass of HNO3 = 1008 g & the mass of H2O = 412 g?