Final answer:
The empirical formula of acetic acid is CH₂O, derived from analyzing the combustion products. Knowing that the molar mass of acetic acid is 60.05 g/mol and the molar mass of the empirical formula is 30.02 g/mol, we find that the molecular formula is C₂H₄O₂ or CH₃COOH, which is double the empirical formula.
Step-by-step explanation:
To determine the empirical formula of acetic acid, we start by analyzing the combustion products. From the given mass of CO₂ and H₂O, we can calculate the moles of carbon and hydrogen. The mass of CO₂ (6.21g) corresponds to 6.21g / 44.01g/mol = 0.1410 moles of C. The mass of H₂O (2.54g) gives 2.54g / 18.02g/mol = 0.1410 moles of H. Since oxygen is the remaining element, its mass in the acetic acid sample can be determined by subtraction from the total mass (4.24g). The empirical formula is based on the lowest whole number ratio of elements in a compound. In this case, the ratio of C:H:O is 1:2:1. Thus, the empirical formula of acetic acid is CH₂O. Given the molar mass of acetic acid is 60.05 g/mol, and the molar mass of the empirical formula (CH₂O) is 30.02 g/mol, we determine that the molecular formula is twice the empirical formula because 60.05 = 2 x 30.02. Therefore, the molecular formula of acetic acid is C₂H₄O₂ or CH₃COOH.