Chemistry
posted by Sofia .
How do you determine the percent composition by mass of a 100 g K2SO4 solution containing a 20g solute. What is the mole percent composition of the solute, assuming that the solution consists of 100 g water and 20 g of K2S04?
For percent composition of K2S04, I got 44.9 % K, 18.4 % S, and 36.7 % O, but I'm not sure if that's right. I have no idea how to determine the mole percent composition, though. If anyone can help me with this problem, I'll truly appreciate it!

For mole composition, you would convert each to moles and then determine the percent of each to the total.

Thank you for the help : ) I just have 2 questions:
Was the percent composition for K2SO4 that I calculated correct? Also, would I convert the 20 g of K2SO4 to moles, and then find the individual moles of each element in that compound? Thanks again for the help! 
For percent composition K, S, and O, your numbers are correct; however, I don't think that is the answer to the question. As I read the question, you have 20 g K2SO4 in 100 g solution. The question is what is the percent K2SO4. That is 20%.