chemistry
posted by Sarah on .
How many oxygen atoms are in 10.3 g of CuSO4*5H2O?
What is the mass percent of carbon in C(12)H(22)O(11)?

1. divide by molar mass of CuSO4*5H2O to convert to mole and multiply by avocado's number (6.022 × 10^23) to find how many atoms there are
2. [12(12.01)/total mass] x 100% 
1. (10.3g CuSO4*5H2O)(1 mole /____M.M.CuSO4*5H2O)(6.022 × 10^23 atoms 6.022 × 10^23/ 1 mole)
notice all the units cancel except for atoms 
I disagree with TutorCat with regard to #1. I agree with what is there; however, the answer provided with that calculation will be the number of molecules of CuSO4*5H2O. The question asks for number of oxygen atoms. Therefore, take the number in TutorCat's answer, and multiply by 9 to obtain the number of oxygen atoms.
Also, I would like to make a correction. It's Avogadro's number and not avocado's number. This is a man's name, not a fruit. 
opps! I overlooked the oxygen part.