Calcium fluoride, CaF₂(s), is sparingly soluble in water. Two separate experiments are performed at the same temperature with identical volumes of a saturated CaF₂ solution that is in equilibrium with excess solid CaF₂.
• In Experiment 1, solid sodium nitrate, NaNO₃(s), is added to the saturated CaF₂ solution.
• In Experiment 2, solid sodium fluoride, NaF(s), is added to an equal volume of the same saturated CaF₂ solution.
Assume complete dissolution of each sodium salt and that no temperature change occurs.
(1) For each experiment, state whether the solubility of CaF₂ will increase, decrease, or remain unchanged after the sodium salt dissolves. Justify each prediction.
(2) Explain why the magnitude of any change in CaF₂ solubility differs between the two experiments even though equal masses of sodium salts are used.