Empirical Formula from Combustion Data

Empirical Formula from Combustion Data - Combustion...

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Combustion Analysis Hydrocarbons burn in the presence of oxygen (O 2 ) to produce CO 2 and H 2 O. Knowing the amount of CO 2 and H 2 O produced permits calculation of the compound's empirical formula. A generic hydrocarbon: C x H y O z N q where the subscripts x, y, z and q are what you are finding. Some Rules and things to watch for: 1. Each carbon atom makes ONE CO 2 molecule. Therefore the moles of CO 2 = moles of carbon 2. It takes 2 H atoms to make one H 2 O molecule. Therefore moles H = twice the moles of water 3. The mass of H and C are found from the number of moles using molar mass of each. 4. The sum of the masses of CO 2 , H 2 O (and any other products of combustion) will ALWAYS be greater than the original sample mass because some mass of oxygen gets added in the process. 5. The sum of the mases of C and H (and N, S etc) may or may not add up to the original sample mass. Consider these three possibilities: (i) Mass of all C, H, and other known elements = original sample mass
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This note was uploaded on 01/05/2012 for the course CHEM 111 taught by Professor Lemaster during the Fall '08 term at Boise State.

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Empirical Formula from Combustion Data - Combustion...

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