Calculating equilibrium concentrations

[Melody Haratian 2J]

Hi guys! When you’re calculating for equilibrium concentrations using ICE tables, when can you ignore the value of X in the denominator?

[Jayasree Peri 2J]

If the K-value is less than 10^-4, you can ignore it. I believe Dr. Lavelle also said 10^-3 in a lecture, but I think it's safer to use 10^-4 because sometimes a K-value with 10^-3 might make a difference in the concentrations.

[Winzel Payumo 1B]

To add on, you can also check by dividing x by your concentration, and if you obtain an answer that it's less than 5%, then it's safe to say that x is negligible.

[David Liu 1E]

he said less than 10^-4 during lecture you can ignore the bottom x, and like the person said above, once you check the ionization/deprotonated species % that also has to be less than 5% once you ignore 10^-4