I've never done this before.. I hope it works...

(Q)What is the exact formula of CuSO4-XH20? Show all the steps that you used to determine the value of X. Remember that X must be a positive interger.
So it was this lab where we had an unknown substance... CuSO4-*X*H20.. and we had to find the value of x.
CuS04-XH20(s)--> XH2O(l) + CuSO4(s) That is the formula
The initial amount of CuSO4-XH20 is 1.59g
The mass of CUSO4 is 1.02g
Hope that makes sense:S

soooo...

you know the mass of the hydrated salt (CuSO4*xH2O)
and you know the mass of the salt after the water was removed (CuSO4)

so what do you get when you subtract them.. . the mass of the water, right?

so then its all about moles. Take the mass of the CuSO4 and use the molecular weight of CuSO4 to get moles CuSO4.

take the mass of water and determine the moles water.

these numbers will not be a nice ratio. Lets say, and this is NOT the answer you'll get, that the moles of salt = 0.0062 and the moles water = 0.0186.

divide both by the smaller number, the moles of salt. Then 0.0062/0.0062 = 1
and 0.01922/0.0062 = 3.1

even though the ratio is not perfect integers 1:3.1 is essentially 1:3

so in my example the formula would be CuSO4*3H20... again, this isn't the answer.

Okay sounds good thanks