A mixture is prepared by dissolving 4.00 g of iron(II) chloride, FeCl₂(s)
CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
A mixture is prepared by dissolving 4.00 g of iron(II) chloride, FeCl₂(s), and 4.00 g of iron(III) chloride, FeCl₃(s), in sufficient water to make 1.00 L of solution. Both salts are highly soluble.
A student sketches a particle-level diagram for a small, fixed-volume region of the solution. The student’s sketch contains an equal number of Fe²⁺ and Fe³⁺ ions and twice as many Cl⁻ ions as the total number of iron ions.
(a) Calculate the number of moles of Fe²⁺, Fe³⁺, and Cl⁻ ions actually present in the bulk solution.
(b) Using mole ratios, determine whether the student’s sketch accurately reflects the true ionic composition. Quantify any discrepancies.
(c) Construct a corrected particle-level diagram for the same fixed-volume region, clearly indicating the relative numbers of Fe²⁺, Fe³⁺, and Cl⁻ ions. Show at least one properly oriented water molecule in the hydration shell of each distinct cation.
(d) Discuss how the possibility of multiple oxidation states for iron complicates the task of ensuring charge balance and stoichiometric accuracy in particulate representations.