Question

Suppose you place 1.0 g of Cu(IO3)2 in contact with 50 mL of distilled water and gently stir. Show graphically how the concentrations of Cu2+ and IO3- in solution will change with time, assuming that solid and liquid are placed in contact at t=0. The plot should be qualitative.

Answer 1

Cu(IO3)2 is a sparingly soluble salt. When put in contact with water, such salts dissolve to produce small concentrations of their ions. When the maximum amount possible of the salt has dissolved, a heterogeneous equilibrium exits between the solid and dissolved ions of the salt.

Cu(IO3)2 (s) <==> Cu^2+ (aq) + 2 IO3^-

When Cu(IO3)2 is dissolved in water, concentration of Cu^2+ and IO3^- will increase. However after some time a saturated solution will form. This is a equilibrium condition where no Cu(IO3)2 will dissolve any more.