Ksp vs Ka: What's the difference and how does it relate to precipitation?

In summary, the conversation discusses the differences between Ksp and Ka and their relationship to precipitation. It is mentioned that Ksp only considers the products and that Ag+ may precipitate first due to the insolubility of AgCl. However, if all compounds were assumed to be soluble, the equation Ksp = [.1][Cl-] can be used to determine which compound will precipitate first. It is also mentioned that Ksp is used to determine if a new phase will emerge, while Ka cannot be used for this purpose.
  • #1
muffintop
14
0

Homework Statement


NaCl is added slowly to a solution that is 0.010M in each Cu+, Ag+ and Au+. Ksp's are 1.9x10^-7, 1.8x10^-10 and 2.0x10^-13 respectively. Which compound will precipitate first?


Can anyone tell me how the Ksp is different from Ka? and the relationship to precipitation?
 
Physics news on Phys.org
  • #2
k is just a concentration constant, sp= solubility, a = acid. same concept, different setups, however. ksp only cares about the products.


I'm guessing Ag+ precipitates first, because AgCl is insoluble. the rest are. (I'm not 100% sure, however.)

But if we assumed they were all soluble...
ksp = [.1][Cl-]

substitute stuff into that equation.
the one that gives the lowest concentration of Cl- precipitates first
 
  • #3
Google solubility product.
 
  • #4
cadillac said:
same concept, different setups

To some extent yes, but there are important differences. You can't use Ka to decide if the new phase emerges, you can use Ksp for that. Reaction quotient for acid solution always equals Ka, reaction quotient for solution containing weakly soluble salt doesn't have to.
 

1. What is Ksp in chemistry?

Ksp, or solubility product constant, is a measure of the maximum amount of a compound that can dissolve in a given solvent at a specific temperature. It is a unique value for each compound and is used to predict the solubility of a compound in a solution.

2. How is Ksp calculated?

Ksp is calculated by multiplying the concentrations of the ions in a saturated solution raised to the power of their respective coefficients in the balanced chemical equation. The concentrations can be determined experimentally or by using the molar solubility of the compound.

3. What is precipitation in chemistry?

Precipitation in chemistry refers to the formation of a solid from a solution. This occurs when the solubility limit of a compound is exceeded and the excess ions combine to form a solid that separates from the solution.

4. How does Ksp affect precipitation?

Ksp plays a crucial role in determining whether a precipitation reaction will occur. If the product of the ion concentrations in a solution exceeds the Ksp value, precipitation will occur. If it is less than the Ksp value, the solution is unsaturated and no precipitation will occur.

5. Can Ksp be affected by temperature?

Yes, Ksp values can change with temperature. Generally, as temperature increases, the solubility of a compound increases, leading to an increase in Ksp. However, there are exceptions to this trend, and the effect of temperature on Ksp must be determined experimentally for each compound.

Similar threads

  • Biology and Chemistry Homework Help
Replies
4
Views
3K
Replies
36
Views
2K
  • Biology and Chemistry Homework Help
Replies
2
Views
3K
  • Introductory Physics Homework Help
Replies
6
Views
4K
Replies
2
Views
6K
  • Biology and Chemistry Homework Help
Replies
2
Views
2K
  • Advanced Physics Homework Help
Replies
1
Views
2K
Replies
22
Views
22K
  • MATLAB, Maple, Mathematica, LaTeX
Replies
6
Views
3K
  • Science and Math Textbooks
Replies
2
Views
3K
Back
Top