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I have tried this question several times but I can't get the right answer and I don't know what I am doing wrong. I have asked some classmates and they got the answer to be C5H60.

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- Thread starter DavidQT
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- #1

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I have tried this question several times but I can't get the right answer and I don't know what I am doing wrong. I have asked some classmates and they got the answer to be C5H60.

- #2

Borek

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Please note this should land in homework forums. Moving.

- #3

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Wikipedia says crocetin is C20H24O6

Divide it all by four and your answer is correct :)

Divide it all by four and your answer is correct :)

- #4

Borek

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Wikipedia says crocetin is C20H24O6

Divide it all by four and your answer is correct :)

It either is, or is not. It fits the formula, but we don't know if it fits data they were given (and they will be graded for the latter, not for their ability to google).

- #5

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Ok I have a test tomorrow and I still dont get this question.

Crocetin consists of elements carbon, hydrogen and oxygen. Determine the empirical formula of crocetin, if 1.00g of crocetin forms 2.68g of carbon dioxide and 0.657g of water when it undergoes complete combustion.

This is what i did:

2.68/44.01=0.0609 mols of carbon dioxide. 0.657/18.02=0.0365 mols of water.

0.0609/0.0365=1.67 0.0365/0.0365=1

1.67x3= 5 to get it even for the empirical formula. 1x3=3 Have to multiply by 3 to both.

Empirical formula= (CO2)5 (H20)3=C5H6O13. Im pretty sure the answer is C5H60

- #6

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Dividing by 4 does not work anyways 6 oxygen's divided by 4 does not equal 1 oxygen.

- #7

Borek

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Typo, crocetin doesn't contain 6 oxygen atoms but 4.

- #8

Borek

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2.68/44.01=0.0609 mols of carbon dioxide. 0.657/18.02=0.0365 mols of water.

0.0609/0.0365=1.67 0.0365/0.0365=1

1.67x3= 5 to get it even for the empirical formula. 1x3=3 Have to multiply by 3 to both.

Empirical formula= (CO2)5 (H20)3=C5H6O13. Im pretty sure the answer is C5H60

You are assuming that products of combustion contain the same amount of oxygen as crocetin did. That's obviously impossible - you have 2.68+0.657=3.34 g of products, but there was only 1 g of crocetin. No wonder your oxygen is so off.

- #9

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Then how would I go about fixing my mistake.

- #10

Borek

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Enough spoon feeding for today, now you are on your own.

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