I might be overthinking this but my reference books, note and the internet don't have much on this topic.
What is the relationship between the solubility product constant Ksp and temperature?
A. They are directly proportional
B. The two are unrelated
C. They are inversely proportional
D. When dissolution is endothermic, Ksp increases as the temperature increases.
I know that Ksp has only one value for a given solid at a given temperature, and that Ksp values depend on solubility of a particular substance, and that temperature affects solubility. Temperature and solubility are inversely proportional, so I think that might be the answer, but I'm not sure as a graph comparing Ksp and Temperature is directly proportional.
However could D be correct? As Solubility of a solute increases with increasing temperature if ΔHsoln is endothermic?
Any help would be appreciated. Thank you in advance.
-Sydney
3 answers
A is right MOST of the time but not all the time. Most salts do increase solubility with increased temperature but not all of them do that. See this graph.
https://courses.lumenlearning.com/boundless-chemistry/chapter/factors-affecting-solubility/
You know B can't be right.
Answer C has the same problem as answer A. C is right some of the time but only now and then as A is right most of the time.
I think the answer to the question D. That is correct all of the time.
By the way, I don't agree with your statement that Temperature and solubility are inversely proportional, which is answer C for the reasons stated above. The solubility depends upon the delta Hsolution
For an exothermic: solid + solute ==> solution + heat
For an endothermic: solid + solute + heat ==> solution.
Le Chatelier's principle tells you solubility decreases with increasing T for exothermic and increases with increasing T for endothermic