(a) Combustion analysis of toluene, a common organic solvent, gives 5.86 mg of CO₂ and 1.37 mg of H₂O. If the compound contains only carbon and hydrogen, what is its empirical formula?

검증된 단계별 안내

Convert the mass of CO₂ to moles of carbon: Use the molar mass of CO₂ (44.01 g/mol) to find the moles of CO₂, then use the ratio of carbon in CO₂ (1 mole of C per mole of CO₂) to find the moles of carbon.

Convert the mass of H₂O to moles of hydrogen: Use the molar mass of H₂O (18.02 g/mol) to find the moles of H₂O, then use the ratio of hydrogen in H₂O (2 moles of H per mole of H₂O) to find the moles of hydrogen.

Determine the simplest whole number ratio of moles of carbon to moles of hydrogen: Divide the moles of each element by the smallest number of moles calculated in the previous steps.

Write the empirical formula: Use the whole number ratio from the previous step to write the empirical formula of the compound.

Verify the empirical formula: Ensure that the empirical formula is consistent with the given data and the assumption that the compound contains only carbon and hydrogen.

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주요 개념

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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 compound. This method is essential for deriving empirical formulas, as it provides the necessary data to relate the mass of the products back to the elements in the compound.

Empirical Formula

The empirical formula of a compound represents the simplest whole-number ratio of the elements present in that compound. It is derived from the mass of each element obtained from combustion analysis and is crucial for understanding the basic composition of the substance. For example, if a compound contains carbon and hydrogen, the empirical formula will indicate the ratio of carbon atoms to hydrogen atoms, which can be determined from the moles of each element calculated from their respective masses.

Mole Concept

The mole concept is a fundamental principle in chemistry that relates the mass of a substance to the number of particles (atoms, molecules, etc.) it contains. One mole of any substance contains Avogadro's number of entities, approximately 6.022 x 10^23. In combustion analysis, converting the mass of CO2 and H2O produced into moles allows for the determination of the moles of carbon and hydrogen in the original compound, which is essential for calculating the empirical formula.

(a) Combustion analysis of toluene, a common organic solvent, gives 5.86 mg of CO2 and 1.37 mg of H2O. If the compound contains only carbon and hydrogen, what is its empirical formula?