Barium chromate, BaCrO₄(s), is a yellow sparingly soluble salt. A beaker contains water in which excess BaCrO₄(s) has been stirred until equilibrium is established at constant temperature. A separate solid sample of potassium chromate, K₂CrO₄(s), is then added to the beaker, dissolving completely.
(1) Before any K₂CrO₄ is added, sketch or describe a particulate-level diagram representing a small region near the surface of an undissolved BaCrO₄ crystal in equilibrium with the surrounding solution. Include and label Ba²⁺(aq), CrO₄²⁻(aq), water molecules, and BaCrO₄(s).
(2) After the K₂CrO₄ dissolves and the system returns to equilibrium, sketch or describe how your particulate diagram would change. Highlight differences in ion concentrations and the amount of solid present.
(3) Explain, in words, how the macroscopic appearance of the mixture (color intensity and amount of solid) is expected to change as a consequence of adding K₂CrO₄.