A chemist has a mixture that is 78.0 % by mass KCl and 22.0 % by mass K₂SO₄
CHEMISTRY · Multi-part · CBSE · Chemistry · Some Basic Concepts of Chemistry · Some Basic Concepts of Chemistry
Problem
A chemist has a mixture that is 78.0 % by mass KCl and 22.0 % by mass K₂SO₄. She wishes to prepare 100.0 mL of an aqueous solution in which the concentration of chloride ion is 0.150 mol L⁻¹. No other chloride sources are available.
(a) Derive an algebraic expression for the mass of the mixture that must be dissolved, making clear how both salts contribute to the chloride ion content.
(b) Use the expression from part (a) to calculate the required mass of the mixture (to the nearest milligram).
(c) After weighing out the calculated mass, the chemist accidentally transfers only 98.5 mL of solution to a volumetric flask before diluting to the 100.0 mL mark. Determine the actual molarity of chloride ion in the final solution and evaluate whether the deviation exceeds ±2 % of the target value.
(d) Propose one procedural modification that would minimize concentration error when preparing solutions from heterogeneous salt mixtures, and justify your recommendation using chemical reasoning.