A pure sample of a binary compound containing only Phosphorous and Sulphur weighs . Elemental analys — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question
Question
A pure sample of a binary compound containing only Phosphorous and Sulphur weighs $2.20\text{ g}$. Elemental analysis reveals that it contains exactly $1.24\text{ g}$ of Phosphorous. Applying the laws of stoichiometry, determine the total number of atoms present in one single molecule of its empirical formula. (Atomic weights: $P = 31$, $S = 32$)
💡 Solution & Explanation
Step 1: Calculate the mass of Sulphur in the compound. Mass of Sulphur = Total Mass - Mass of P = $2.20\text{ g} - 1.24\text{ g} = 0.96\text{ g}$. Step 2: Calculate the number of moles of each element. Moles of P = $\frac{1.24\text{ g}}{31\text{ g/mol}} = 0.04\text{ moles}$. Moles of S = $\frac{0.96\text{ g}}{32\text{ g/mol}} = 0.03\text{ moles}$. Step 3: Determine the simplest molar ratio. Ratio $P : S = 0.04 : 0.03 = 4 : 3$. The empirical formula of the compound is $P_4S_3$. The total number of atoms in this empirical formula is $4 + 3 = 7$.