In a complex precipitation sequence, of is rapidly mixed with of . Assuming the reaction proceeds to — Mole Concept and Some Basic Concepts of Chemistry Chemistry Question
Question
In a complex precipitation sequence, $100\text{ mL}$ of $0.06\text{ M } Ca(NO_3)_2$ is rapidly mixed with $50\text{ mL}$ of $0.06\text{ M } Na_2C_2O_4$. Assuming the reaction proceeds to absolute completion and forms the completely insoluble salt Calcium oxalate ($CaC_2O_4$), which of the following statements define the final equilibrium state?
💡 Solution & Explanation
Step 1: Reaction: $Ca^{2+} + C_2O_4^{2-} \rightarrow CaC_2O_4 \downarrow$. Step 2: Initial millimoles. $Ca^{2+} = 100 \times 0.06 = 6\text{ mmol}$. $C_2O_4^{2-} = 50 \times 0.06 = 3\text{ mmol}$. Step 3: Limiting reagent is Oxalate ($3\text{ mmol}$). Thus, $Na_2C_2O_4$ is the LR (Statement C is true). $Ca(NO_3)_2$ is in excess (Statement D is false). Step 4: Precipitate formed = $3\text{ mmol} = 0.003\text{ moles}$ (Statement A is true). Step 5: Excess $Ca^{2+} = 6 - 3 = 3\text{ mmol}$. Final volume = $100 + 50 = 150\text{ mL}$. Final $[Ca^{2+}] = 3 / 150 = 0.02\text{ M}$ (Statement B is true).