[freudchicken06]

I'm having a problem figuring out two problems I have that are due tomorrow.  My professor assigned these today and I have been trying all day but can't seem to figure them out.  Please *delete me*

1. A 0.755-g. sample of hydrated copper(II) sulfate was heated carefully until it had changed completely to anhydrous copper(II) sulfate with a mass of 0.483 g. Determine the number of water molecules per molecule of copper(II) sulfate in the original material, and give the material a proper chemical name.

2. (a) The density of a 0.350 M solution of ammonium sulfate is 1.027 g/mL. What is the mass percentage composition of this solution?
(b) Nitric acid is purchased from chemical suppliers as a solution that contains 70% of acid by mass. What is the molarity of this solution? The density of 70% nitric acid is 1.43 g/cm3(cubed).

[Borek]

You must show what you did. Please read forum rules.

[english]

I'm having a problem figuring out two problems I have that are due tomorrow.  My professor assigned
(b) Nitric acid is purchased from chemical suppliers as a solution that contains 70% of acid by mass. What is the molarity of this solution? The density of 70% nitric acid is 1.43 g/cm3(cubed).

All I can help you with at this moment until you try it yourself, is that 1.43 g/cm³ = 0.00143 g/L, because 1 cm³ = 1 mL = 0.001 L.  Write that down.

Now use your knowledge of stoichiometry to convert this into mol/L.  Don't forget your percentage, 70 %.

This is all you are doing in these problems.