@@starbeom The 2x represents the molarity and the fact that the initial reactant produces two of those cations in solution. So, if the solution started with 1M Na2S (for example) and that substance dissociated, it would produce two Na ions, and the total Na concentration would be 2M. Separately, the square is how the stoichiometric coefficient is represented in the Ksp equation. This is a really confusing idea, and most students feel that the 2 is being double-counted when we use 2x^2. Hang in there.
Think about it like you have $1,000,000 + $0.01; the 1¢ is so meaningless compared to the million dollars you have. With the 2x, it’s like $1,000,000 + $0.02; 2¢ is still insignificant to the million dollars.
This is actually #1 on my list of stuff to do! I hear ya! I got really bogged down with my actual job :) so I've had to take a break for a while. I'll be back at it in a week. Tell me which problems you'll need (not today, but starting in about a week) and I'll move them to the top of my list!
