An unknown, biologically active synthetic compound possesses exactly sulphur by mass. Calculate the — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question

💡 Solution & Explanation

Step 1: Understand the theoretical constraint of "minimum molecular mass". To have the smallest possible molecular weight while maintaining the percentage composition, the molecule must contain the absolute minimum number of atoms of the target element. This absolute minimum is exactly 1 atom. Step 2: Set up the mathematical relationship. Therefore, 1 mole of the compound must contain at least 1 mole of Sulphur atoms ($32\text{ g}$). Step 3: Utilize the given percentage. This $32\text{ g}$ strictly represents exactly $8\%$ of the total minimum molecular mass ($M_{min}$). $\frac{8}{100} \times M_{min} = 32$. Step 4: Solve for $M_{min}$. $M_{min} = \frac{32 \times 100}{8} = 400\text{ g/mol}$.