Combustion analysis of 45.62 mg of toluene, a commonly used solvent, gives 35.67 mg of H2O and 152.5 mg of CO2. What is the empirical formula of toluene?

Verified step by step guidance

1. Convert the mass of H2O to moles of H2O using its molar mass (18.02 g/mol).
2. Determine the moles of hydrogen in the sample by noting that each mole of H2O contains 2 moles of hydrogen atoms.
3. Convert the mass of CO2 to moles of CO2 using its molar mass (44.01 g/mol).
4. Determine the moles of carbon in the sample by noting that each mole of CO2 contains 1 mole of carbon atoms.
5. Assume the rest of the mass is due to carbon and hydrogen, and calculate the empirical formula by finding the simplest whole number ratio of moles of carbon to moles of hydrogen.

Key Concepts

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. This method is essential for deriving empirical formulas from the mass of the combustion products.

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 relative amounts of each element, which can be calculated from the mass of the elements obtained through combustion analysis. Understanding how to convert mass data into mole ratios is crucial for determining the empirical formula.

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 particles (approximately 6.022 x 10^23). This concept is vital for converting the mass of combustion products into moles, allowing for the calculation of the empirical formula based on the mole ratios of the constituent elements.