5% rule clarification

Moderators: Chem_Mod, Chem_Admin

Ami_Pant_4G
Posts: 106
Joined: Sat Aug 24, 2019 12:17 am

5% rule clarification

Postby Ami_Pant_4G » Mon Jan 20, 2020 9:33 am

When approximating for a small Ka, should we always calculate % ionization to ensure it is lower than 5%? Thanks in advance.

Christineg1G
Posts: 115
Joined: Fri Aug 09, 2019 12:15 am
Been upvoted: 1 time

Re: 5% rule clarification

Postby Christineg1G » Mon Jan 20, 2020 9:48 am

If k<10^-3 you can attempt an approximation. To ensure the validity of your approximation, you should check by dividing the x value you received over the initial concentration. If this value is less than 5%, your approximation is valid.

Jessica Chen 2C
Posts: 103
Joined: Thu Jul 11, 2019 12:17 am

Re: 5% rule clarification

Postby Jessica Chen 2C » Mon Jan 20, 2020 11:25 am

Yes, if you approximate for a small x value (when K<10^-3), you have to check that the value of x is less than 5% of the initial concentration in order for the approximation to be valid.


Return to “Equilibrium Constants & Calculating Concentrations”

Who is online

Users browsing this forum: No registered users and 4 guests