Empirical formulae - the uses
A 1.000g sample of an unknown hydrocarbon containing only carbon and hydrogen is burned in excess oxygen to yield carbon dioxide and water. The masses of CO2 and H2O are 2.994g and 1.635g, respectively. What is the empirical(simplest) formula for this compound?
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In a compound of the form CxHy on combustion, all C ends up in CO2 and all H in H2O.
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<br>The molar mass of CO2 is 44.098g/mol. Therefore the number of moles of CO2 formed = 2.994g/(44.098g/mol)=.0679mol
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<br>Now, the mass of carbon in 2.994gram of CO2
<br>= .0679mol*12.01g/mol
<br>= .815479g
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<br>But this carbon originally came from the 1gram sample of the unknown compound. Thus the mass percent of carbon in this compound is
<br>= .815479g * 100%/ 1g = 81.55%
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<br>Since the compound ...
Solution Summary
Finding the empirical formula of a compound is explained with more than 50 words text.