skogias6733 wrote:Hi,

Regarding page 127, i noticed that when calculating the Ksp, the concentration must be raised to the power of the ions coefficient , for example

Ag+ becomes Ksp = [x]

whereas 2Ag+ = [2x]^2 just wondering..

1) why we have to account for the 2, twice once with the 2 in the 2x and then again by squaring it?

(1) When you are doing Keq or other equilibrium constants, the square brackets [] represents concentration in mol/L. You would never "account for the 2, twice".

However, it is different for Ksp and the reason is shown in the step-by-step calculation in the book.

This is more than you need, but if you want a different way to look at the calculations:

https://studylib.net/doc/8131747/proble ... g-with-kspskogias6733 wrote:2) is this only when solving for Ksp that we have to account for the coefficient twice?

(2) You do not need to memorize this information because, if needed during the exam, the information will be provided and often provided with an example.

Nonetheless, this type of calculation for GAMSAT is unique to Ksp. However, it is not as simple as saying Ksp "account for the 2, twice". Why? It depends on what you are calculating.

Either:

1) You are given the actual concentration, in which case, that is the ONLY number that you use. You would not multiply by 2 but you would raise to the power of 2. Notice that in the equation that you put in your post, that you inadvertently replaced the s for solubility (from the book) with x which often represents the actual concentration. {Side note: Of course, it never matters what letter you use to represent an idea as long as you know what that letter represents.}

2) You are trying to determine the solubility of an ion, then you need to "account for the 2, twice" (or the 3, or whatever the stochiometric coefficient is).

PS: You are doing great! Keep up the good work!