5I.29

[Alexis Webb 2B]

After doing the ICE table for this problem, the equation is 3.2x10^-34=x^2/(0.22-2x^2). The book says that we can omit the 2x^2 because we can assume that x <<0.22 since K is so small. That means the denominator would just be (0.22)^2. I am not really sure how I would know to do this if I had another problem like this. Can someone explain why we can do this and when we do this?

[Kyle Rex 1K]

Honestly, its really situational when you'd have to omit something, so if you're ever confused you could just solve for x with it being in the top and bottom, and in the end the solution (omitting the 2x^2 or not) would pretty much be the same.

[Sanjana K - 2F]

5% Rule: If x/(initial concentration) < 5%, then you can ignore the "-2x" term but if not, then you'd need to use the quadratic formula. Make sure you write out the rule to justify ignoring the "-x" terms whenever you have this type of problem