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
I don't like the question for I think it is misleading.
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
D. When dissolution is endothermic, Ksp increases as the temperature increases.
Thank you for taking the time to answer, and clarifying the role of temperature, when I looked up the inverse relationship, nothing was mentioned of a directly proportional relationship, so thank you for saving me time and the embarrassment of having wrong information on a subject.
To determine the relationship between the solubility product constant (Ksp) and temperature, let's break it down step by step:
1. First, recall that the solubility product constant (Ksp) is an equilibrium constant that represents the extent to which a solid solute dissolves in a solvent to form a saturated solution.
2. Ksp is calculated by multiplying the concentrations of the products raised to the power of their stoichiometric coefficients in the balanced equation for the dissolution reaction.
3. The solubility of a substance generally depends on temperature. In many cases, as temperature increases, the solubility of a solid solute also increases. This is because an increase in temperature provides more energy to overcome the attractive forces holding the solute particles together, allowing for more particles to dissolve.
4. Now, let's consider the answer choices:
- Option A states that Ksp and temperature are directly proportional. However, Ksp is a constant and does not change with temperature. Therefore, option A is incorrect.
- Option B suggests that Ksp and temperature are unrelated. While Ksp itself is not affected by temperature, the solubility and, subsequently, the concentration of the dissolved species may change with temperature. Therefore, option B is not entirely accurate.
- Option C suggests that Ksp and temperature are inversely proportional. This is also not entirely accurate since Ksp itself remains constant regardless of temperature.
- Option D states that when dissolution is endothermic (ΔHsoln > 0), Ksp increases as the temperature increases. This statement is generally true. Endothermic dissolution means that the dissolution of the solute requires the input of heat energy. When the temperature increases, more heat energy is available, enhancing the dissolution process and leading to higher solubility, which in turn results in a higher Ksp value.
Based on the explanation above, option D is the most accurate answer to your question. However, it's essential to keep in mind that Ksp itself does not change with temperature; rather, it is the solubility and concentration of the dissolved species that are affected.