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Topic: Molecular Formula  (Read 6223 times)

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Offline 350chev

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Molecular Formula
« on: October 17, 2009, 12:27:03 AM »
Thanks for all your help with the last few questions I had! Sorry if I didnt respond soon enough but I managed to get them with the help. But now I have another question...

Maleic acid is an organic compound composed of 41.39% C, 3.47% H, and the rest oxygen. If 0.129 mol of maleic acid has a mass of 15.0 g, what are the empirical and molecular formulas of maleic acid?

Ok so I found the CHO as the empirical formula but I cant figure out how to get the needed C4H4O4 for the maleic acid?

Offline orgoclear

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Re: Molecular Formula
« Reply #1 on: October 17, 2009, 02:08:26 AM »
0.129 moles has a mass of 15.0 g
So calculate the weight of 1 mole of malic acid then divide this by the mass of the empirical formula (why?) (round it off to the nearest integer) this is to know how many of these are there in one mole.

Like if you get the answer as 3 and the empirical formula is COH then the compound would be (COH)3 (Note: This is not the actual answer. You still have to do the calculations)


Offline 350chev

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Re: Molecular Formula
« Reply #2 on: October 17, 2009, 02:34:25 PM »
0.129 moles has a mass of 15.0 g
So calculate the weight of 1 mole of malic acid then divide this by the mass of the empirical formula (why?) (round it off to the nearest integer) this is to know how many of these are there in one mole.

Like if you get the answer as 3 and the empirical formula is COH then the compound would be (COH)3 (Note: This is not the actual answer. You still have to do the calculations)



Ok so I cross multiplied .129/15 and 1/X to get 116.27906 then divided the 116.27906 by 15 to get 4.008 which would create the C4H4O4 compound of the acid.

Thanks! I seems to always miss a small crucial step :(

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