Estimation Of Carbon And Hydrogen

Question

In the combustion method, 0.20 g of an organic compound on complete combustion produced 0.366 g of carbon dioxide; what is the percentage of carbon in the compound (C = 12, O = 16)?

RankGuru · Accepted Answer

Carbon and hydrogen are estimated by burning a known mass of the organic compound in a stream of oxygen so that carbon is converted into carbon dioxide and hydrogen into water, which are absorbed and weighed. The percentage of carbon is obtained from %C = (12 / 44) x (mass of CO2 / mass of compound) x 100, where 44 is the molar mass of carbon dioxide and 12 is the atomic mass of carbon, since each mole of carbon dioxide contains one mole of carbon. Substituting the data: %C = (12 / 44) x (0.366 / 0.20) x 100 = 0.2727 x 1.83 x 100 = 50%. The value 18.3% wrongly omits the 12/44 carbon fraction and uses only the mass ratio. The value 8.33% inverts part of the calculation by misplacing the molar masses. The value 27.3% reports only the 12/44 fraction as a percentage without multiplying by the mass ratio of carbon dioxide to compound. This is the NCERT Liebig combustion relation for carbon. Plausibility check: a carbon content of 50% is typical for many organic compounds, and the magnitude of carbon dioxide produced is consistent with it, confirming the result.

Estimation Of Carbon And Hydrogen

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