A hydrocarbon of unknown formula CxHy was submitted to combustion analysis with the following results. What is the empirical formula of the hydrocarbon?

Verified step by step guidance

1. Step 1: Write the balanced chemical equation for the combustion of the hydrocarbon CxHy: CxHy + O2 -> CO2 + H2O.
2. Step 2: Determine the moles of CO2 and H2O produced from the combustion analysis data.
3. Step 3: Calculate the moles of carbon (C) from the moles of CO2, using the relationship that 1 mole of CO2 contains 1 mole of C.
4. Step 4: Calculate the moles of hydrogen (H) from the moles of H2O, using the relationship that 1 mole of H2O contains 2 moles of H.
5. Step 5: Determine the simplest whole number ratio of moles of C to moles of H to find the empirical formula of the hydrocarbon.

Key Concepts

Combustion Analysis

Combustion analysis is a technique used to determine the empirical formula of a hydrocarbon by burning it in excess oxygen. The products of combustion, typically carbon dioxide (CO2) and water (H2O), are measured to find the amounts of carbon and hydrogen in the original compound. This data allows for the calculation of the mole ratio of the elements, leading to the empirical formula.

Empirical Formula

The empirical formula represents the simplest whole-number ratio of atoms of each element in a compound. It is derived from the amounts of each element present in a sample, often obtained through combustion analysis. For hydrocarbons, the empirical formula is typically expressed as CxHy, where x and y are the smallest integers that reflect the ratio of carbon to hydrogen.

Stoichiometry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. In combustion analysis, stoichiometry is used to relate the moles of CO2 and H2O produced to the moles of carbon and hydrogen in the hydrocarbon. Understanding stoichiometric principles is essential for accurately determining the empirical formula from experimental data.