posted by susan on .
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!
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.
thanks 4 the help
i have the empirical formula,but i'm not able to get the molecular formula.
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.