What is the approximate ratio of the solubility of CaSO4 (Ksp = 2.4 x 10−5) in pure water to the solubility of CaSO4 in 0.10 M Na2SO4 at the same temperature?
3 answers
Dr. Bob is the greatest person of all time if he answers this
CaSO4 ===> Ca^2+ + SO4^2-
For pure water, Ksp = (Ca^2+)[(SO4)^2-]
So (Ca^2+) = x and [(SO4)^2-] = x.
Solve for x and that is the solubility of CaSO4 in pure water.
For the 0.1M Na2SO4 solution.
Ksp is the same expression.
(Ca^2+) = x
[(SOr)^2-] = 0.1 + x.
[Note: that is 0.1M from the Na2SO4 and xc from the CaSO4).
Solve for x and that is the solubility in the 0.1M Na2SO4.
This is the common ion effect. It ALWAYS decreases the solubility of a slightly soluble salt.
Your other question yesterday was tougher than this one. This one is a general chemistry question.
For pure water, Ksp = (Ca^2+)[(SO4)^2-]
So (Ca^2+) = x and [(SO4)^2-] = x.
Solve for x and that is the solubility of CaSO4 in pure water.
For the 0.1M Na2SO4 solution.
Ksp is the same expression.
(Ca^2+) = x
[(SOr)^2-] = 0.1 + x.
[Note: that is 0.1M from the Na2SO4 and xc from the CaSO4).
Solve for x and that is the solubility in the 0.1M Na2SO4.
This is the common ion effect. It ALWAYS decreases the solubility of a slightly soluble salt.
Your other question yesterday was tougher than this one. This one is a general chemistry question.
You have the two solubilities. You will need to calculate the ratio from that.
1 answer