Question

Describe the effect of CaCl_2 on the solutions. Write an equation for the formation of any precipitate.

a. CaCl_2 increases solubility.
b. CaCl_2 forms a colored solution.
c. CaCl_2 induces precipitation.
d. CaCl_2 has no effect on the solutions.

Answer 1

CaCl2 can induce precipitation when added to a solution containing anions that form insoluble compounds with calcium ions, as in the case of CaCl2 and AgNO3 where AgCl precipitates. The equation for the reaction is CaCl2 (aq) + 2AgNO3 (aq) → Ca(NO3)2 (aq) + 2AgCl (s).

Step-by-step explanation:

The effect of CaCl2 on solutions depends on the components present in the said solutions. If CaCl2 is added to a saturated solution of calcium phosphate, it will make the system super-saturated with calcium ions, meaning that the concentration of Ca2+ ions increases, and the solution's solubility product (Q) becomes greater than the solubility product constant (Ksp). This results in precipitation of calcium phosphate to return the system to equilibrium (Q = Ksp).

Here's an example of a precipitation reaction when a solution of CaCl2 is added to a solution of AgNO3, resulting in the formation of insoluble AgCl precipitate:

CaCl2 (aq) + 2AgNO3 (aq) → Ca(NO3)2 (aq) + 2AgCl (s)

This reaction can be represented by three equations: complete chemical equation, complete ionic equation, and net ionic equation. When analyzing reactions for precipitate formation, one should consult solubility rules for ionic compounds to determine if a precipitation reaction is likely to occur.