calculation

Moderators: Chem_Mod, Chem_Admin

Parsia Vazirnia 2L
Posts: 44
Joined: Fri Jul 22, 2016 3:00 am

calculation

Postby Parsia Vazirnia 2L » Thu Nov 24, 2016 3:27 pm

When trying to find the concentration and you have a -x in your K expression, when can you drop the -x in your calculations? for example lets say you are given the value of Ka and it is 3 X 10^-6 and you set it equal to the expression which is X^2/0.20-X. Under what conditions can you ignore the -X and just solve Ka=x^2/0.20? Is there a rough guideline to follow?

Sally_Tu_1H
Posts: 22
Joined: Fri Jul 22, 2016 3:00 am
Been upvoted: 1 time

Re: calculation

Postby Sally_Tu_1H » Thu Nov 24, 2016 5:02 pm

You can drop the "x" when "K" is small. K is small when it is less than 10^(-3); however, it is safer when K is less than 10^(-5). You must check to see that the ionization is less than 5% so that taking the "x" out is valid.


Return to “Equilibrium Constants & Calculating Concentrations”

Who is online

Users browsing this forum: No registered users and 2 guests