Question

Ethylene glycol, commonly used as automobile antifreeze, contains only carbon, hydrogen, and oxygen. Combustion analysis of a 23.46 mg sample yields 20.42 mg of H2O and 33.27 mg of CO2. What is its molecular formula if it has a molecular mass of 62.0 amu?

Answer 1

To find the molecular formula of ethylene glycol, analyze the combustion products and calculate the empirical formula first. The empirical formula is CH2O. The molecular formula of ethylene glycol is C2H4O2.

Step-by-step explanation:

To determine the molecular formula of ethylene glycol, we need to analyze the combustion products and calculate the empirical formula first. From the given data, the combustion of a 23.46 mg sample produces 20.42 mg of H2O and 33.27 mg of CO2.

We can calculate the moles of each element using their molar masses and the masses of the combustion products. From this, we find that the empirical formula is CH2O.

To find the molecular formula, we need to compare the empirical formula mass (30.03 g/mol) to the molecular mass (62.0 amu). The ratio of these two masses is approximately 2, suggesting that the molecular formula is twice the empirical formula. Therefore, the molecular formula of ethylene glycol is C2H4O2.