determine the percent by mass of all the elements in the compound magnesium sulfate heptahydrate? how do i start this? mg is 24.31 sulfur is 32.07 and 7 hydrogens for heptahydrate? add them up? 63.436. if i am doing this correctly what do i do next?

Answer 1

First the formula for magnesium sulfate heptahydrate is MgSO4.7H2O (you forgot the O in the part you wrote about 7 hydrogen for heptahydrate as well as the O in SO4).
You are on the right track though.
a. Determine the formula mass for MgSO4.7H2O. That will be 24.31 + 32.07 + 4*16 + 7*18.015. I looked up the molar mass from a calculator on the web and obtained 246.426 but you should confirm that.
b. Now, %Mg = (mass Mg/formula mass)*100
%S = (mass S/formula mass)*100
% O = (mass O/formula mass)*100
etc. [remember you have O in SO4 as well as O in H2O
c. When you finish, all of the percents should add to 100%.
Post your work if you get stuck.

Answer 2

THANKS SO MUCH DRBOB!! I GOT THE CORRECT ANSWER!!!!!