# Chemistry

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How do I find the percent composition of
H2O: 20.14grams
C2O4: 51.64grams
Fe 3+: 11.34grams
K^+: 15.06 grams

and the empirical formula with these numbers

• Chemistry -

%H2O = (g H2O/total mass)*100 =??
%C2O4 = (g C2O4/total mass)*100 = >>
etc.
Then take a 100 g sample. In a 100 g sample you will have that many g of H2O, C2O4, etc.
Change all grams (from the 100 g sample) to mols.
Find the ratio of moles to each other to obtain the emppirical formula. If you have trouble, post your work and explain what you don't understand.

• Chemistry -

ok well here is what i have gotten so far:

H2O: 1.118 mol
C2O4: .58681 mol
Fe 3+: .2025 mol
K^+: .3862 mol

That is what ive gotten doing 20.14 g(1 mol / 18 g) = 1.118 mol
and so on with the rest of them

Did i do that wrong

• Chemistry -

yes and no.
What did you find for the percents? Not 20.14%.
Total mass is 20.14 + 51.64 + 11.34 + 15.06 = 98.18
%H2O = (20.14/98.18)*100 = 20.51%
%C2O4 = (51.64/98.18)*100 = 52.60%
etc.When you finish, you should have 100%. Then take a 100 g sample which will give you 20.51 g H2O, 52.60 g C2O4, etc.
You have the mols part correct if you had done the percentage correctly. Correct the percentages, then redo the mols, then determine the ratios.

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