Question

Fumaric acid, which occurs in many plants, contains, by mass, 41.4% carbon, 3.47% hydrogen, and 55.1%
oxygen. A 0.050-mol sample of this compound weighs 5.80 g. The molecular formula of this compound is can you show me the formula

Answer 1

Assume 100 g for the first part.

then you have 41.4 g of C, or xxx moles
then you have 3.47 g of H, or yyy moles H
and you have 55.1g of O, or zzz moles of O

Now, look at the xxxx,yyy, zzz numbers. Divide all of them by the LEAST number, you should be able to get a whole number ratio for the three elements.

That will give you the empirical formula.

Now, the mole mass is known:
molmass= 5.80/.050 g

divide the empirical formula mole mass into the known mole mass. That will give you a whole number ratio to multiply the subscripts in the empirical formula by. The result is the actual molecular formula.

Answer 2

I answered this below. It may not have been your post. If not, I'll post a link to the answer.

Answer 3

It WAS your post. Why are you posting the same question again. Didn't you look for the response?
http://www.jiskha.com/display.cgi?id=1254861796