Hello everyone. I was just doing a chem lab involving the composition of the CuSO4 hydrated form. after doing all of the math involved (anhydrous mass subtracted from hydrous mass, division by H2O's molar mass, etc...)

and got:

 

CuSO4 (dot) 3 H2O.

 

but i read online that the only hydrated form of cuso4 was with 5 H2O. Does the one i calculated exist, or did I make an error?

 

thx

It's also possible you didn't evaporate all of the water away.

True, as the anhydride has a higher SG than the 5H2O.

I know I did that lab last year (high school chem) and if you didn't get all the water out, naturally it would seem like you had more CuSO4 then you are supposed to which would screw up your ratio.

 

I suggest going in during office hours and re-running the lab.

That means 159g of CuSO4 in 90g of H2o???? :/

check all your math and if your answer still comes out as 3, simply write an explanation of why that might be and leave it at that.

 

You can get a very high mark in a lab without getting perfect experimental results. Instructors are usually looking more for an understanding of what you're doing than a perfect execution of the method.