Question

Solubility Product

K_sp for Ca(OH)₂ is determined in two separate experiments, both at the same temperature.

1. - by titration of hydroxide in a simple saturated solution of Ca(OH)₂.
2. - by titration of hydroxide in a 0.01 M CaCl₂ solution saturated with Ca(OH)₂.

Identify which of the following statements is either completely "True" or at least partially "False"
(assuming that the activity of each ion is equal to its molar concentration in each instance):

a) True False  You would expect the value for Ksp to be the same from both experiments, since K_sp is a constant at a given temperature.
b) True False  You would expect more Ca(OH)₂ to be able to dissolve in the simple solution, than in the CaCl₂ solution.
c) True False  You would expect the value for K_sp to be lesser in the second experiment, since less Ca(OH)₂can dissolve in the presence of the additional amount of Ca²⁺(aq).
d) True False  You would expect the value for K_sp to be different in the two experiments, since the presence of CaCl₂(aq) affects the equilibrium position.
e) True False  In the second experiment, both [Ca²⁺] and [OH⁻] are greater than in the the first experiment.

Answer 1

a) You would expect the value for Ksp to be the same from both experiments, since K_sp is a constant at a given temperature. - FALSE

b) You would expect more Ca(OH)₂ to be able to dissolve in the simple solution, than in the CaCl₂ solution. - TRUE

c)  You would expect the value for K_sp to be lesser in the second experiment, since less Ca(OH)₂ can dissolve in the presence of the additional amount of Ca²⁺(aq). - TRUE

d) You would expect the value for K_sp to be different in the two experiments, since the presence of CaCl₂(aq) affects the equilibrium position.- TRUE

e)  In the second experiment, both [Ca²⁺] and [OH⁻] are greater than in the the first experiment. - FALSE