A chemist prepares a gaseous hydrocarbon which is found to possess an empirical formula of . If the — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question
Question
A chemist prepares a gaseous hydrocarbon which is found to possess an empirical formula of $CH$. If the vapour density of this gaseous hydrocarbon is experimentally determined to be $39$, what is the exact integer value of the number of carbon atoms present in a single molecule of this gas?
💡 Solution & Explanation
Step 1: Calculate the molar mass from vapour density. Molar Mass = $2 \times V.D. = 2 \times 39 = 78\text{ g/mol}$. Step 2: Calculate the empirical formula mass of $CH$. Empirical Mass = $12 (C) + 1 (H) = 13\text{ g/mol}$. Step 3: Determine the n-factor linking empirical and molecular formulas. $n = \frac{\text{Molar Mass}}{\text{Empirical Mass}} = \frac{78}{13} = 6$. Step 4: The molecular formula is $(CH)_6 = C_6H_6$. The number of carbon atoms per molecule is exactly 6.