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Ch.3 - Chemical Reactions and Reaction Stoichiometry
Chapter 3, Problem 96

An organic compound was found to contain only C, H, and Cl. When a 1.50-g sample of the compound was completely combusted in air, 3.52 g of CO2 was formed. In a separate experiment, the chlorine in a 1.00-g sample of the compound was converted to 1.27 g of AgCl. Determine the empirical formula of the compound.

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1
Calculate the moles of CO2 produced using its molar mass.
Determine the moles of carbon in the sample from the moles of CO2, since each mole of CO2 contains one mole of carbon.
Calculate the mass of carbon in the sample using the moles of carbon and the atomic mass of carbon.
Determine the moles of AgCl produced using its molar mass, and then find the moles of chlorine in the sample, since each mole of AgCl contains one mole of chlorine.
Calculate the mass of chlorine in the sample using the moles of chlorine and the atomic mass of chlorine, then find the mass of hydrogen by subtracting the masses of carbon and chlorine from the total mass of the sample.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Combustion Analysis

Combustion analysis is a technique used to determine the composition of organic compounds by burning them in excess oxygen. The products of combustion, typically carbon dioxide (CO2) and water (H2O), are measured to calculate the amounts of carbon and hydrogen in the original sample. In this question, the mass of CO2 produced allows us to infer the amount of carbon in the compound.
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Stoichiometry

Stoichiometry involves the calculation of reactants and products in chemical reactions based on the conservation of mass. It allows chemists to relate the quantities of substances involved in a reaction. In this case, stoichiometric relationships help convert the mass of CO2 produced into moles of carbon, which is essential for determining the empirical formula of the compound.
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Empirical Formula

The empirical formula of a compound represents the simplest whole-number ratio of the elements present. It is derived from the amounts of each element calculated from experimental data. In this problem, the empirical formula is determined by finding the moles of carbon, hydrogen, and chlorine in the compound and expressing their ratios in the simplest form.
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