# organic chemistry

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i'm having trouble figuring out my unknown compound.
The elemental analysis is 87.28%carbon and 12.72% hydrogen for my unknown liquid, and for my solid unknown the elemental analysis is 79.22% carbon and 5.7% hydrogen and 15.98% oxygen.
I'm not able to figure out the molecular formula for both.Please help!

• organic chemistry -

I can help you get the empirical formula for each.

1) assume you have a sample of 100 g

then 87.28 grams of C, or xxx moles of C
and 12.72 g of H, or yyyy moles of H

Now whichever number of moles is the least, divide that into each xxxx and yyyy. The whole number is the subscripts in the empirical formula. If you do not get a whole number ratio, multiply each number by a common factor until you get a whole number ratio.

I get in my head C4H7 for the empirical formula.
Do the same technique for the second compound

To get the molecular formula from the empirical formula, you need more information.

• organic chemistry -

thanks 4 the help
i have the empirical formula,but i'm not able to get the molecular formula.
Please help

• organic chemistry -

You need more information to obtain the molecular formula. Did you do a freezing point depression to obtain an approximate molar mass? Or some other experiment to determine the approximate molar mass.

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