A solid sample weighing exactly , consisting exclusively of Calcium carbonate () and chemically iner — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question
Question
A solid sample weighing exactly $1.0\text{ g}$, consisting exclusively of Calcium carbonate ($CaCO_3$) and chemically inert Sodium chloride ($NaCl$), reacts completely with $100\text{ mL}$ of a $0.1\text{ N } HCl$ solution. Determine the exact mass percentage of $CaCO_3$ present in the original solid mixture.
💡 Solution & Explanation
Step 1: Identify the reactive component. Only the basic $CaCO_3$ reacts with the acidic $HCl$. The $NaCl$ is inert in this context. Step 2: Calculate the milliequivalents of $HCl$ consumed. Meq of $HCl = N \times V(\text{mL}) = 0.1 \times 100 = 10\text{ meq}$. Step 3: Apply the Law of Equivalence. Meq of $CaCO_3$ reacted = Meq of $HCl$ consumed = $10\text{ meq}$. Step 4: Calculate the mass of $CaCO_3$. The equivalent weight of $CaCO_3$ = $\text{Molar Mass} / 2 = 100 / 2 = 50\text{ g/eq}$. Mass of $CaCO_3 = \text{Equivalents} \times \text{Equivalent Weight} = (10 \times 10^{-3}\text{ eq}) \times 50\text{ g/eq} = 0.5\text{ g}$. Step 5: Calculate percentage composition. % $CaCO_3 = (0.5\text{ g} / 1.0\text{ g}) \times 100 = 50\%$.