Elemental analysis of an unknown organic compound reveals it contains Carbon, Hydrogen, and Nitrogen — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question
Question
Elemental analysis of an unknown organic compound reveals it contains $38.8\%$ Carbon, $16.0\%$ Hydrogen, and $45.2\%$ Nitrogen by mass. If the empirical formula of the compound is strictly expressed as $C_xH_yN_z$ in its simplest integer format, find the arithmetic sum of $(x + y + z)$.
💡 Solution & Explanation
Step 1: Assume a $100\text{ g}$ sample and convert mass percentages to moles. Moles of C $= 38.8 / 12 \approx 3.23\text{ moles}$. Moles of H $= 16.0 / 1 = 16.0\text{ moles}$. Moles of N $= 45.2 / 14 \approx 3.23\text{ moles}$. Step 2: Determine the simplest integer ratio by dividing by the smallest mole value ($3.23$). C $= 3.23 / 3.23 = 1$. H $= 16.0 / 3.23 \approx 4.95 \approx 5$. N $= 3.23 / 3.23 = 1$. Step 3: The empirical formula is $C_1H_5N_1$ ($CH_5N$). Therefore, $x=1$, $y=5$, $z=1$. The sum $x+y+z = 1 + 5 + 1 = 7$.