pH vs pKa

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pH vs pKa

Postby Noh_Jasmine_1J » Thu Jan 24, 2019 11:28 am

what is the difference between pH and pKa? how would you solve for pKa if given pH?

Calvin Patel 2H
Posts: 37
Joined: Fri Sep 28, 2018 12:22 am

Re: pH vs pKa

Postby Calvin Patel 2H » Thu Jan 24, 2019 11:33 am

pKa is the -log(Ka value). pH is the -log(H3O+ concentration). If you are given the pH, you can use 10^-(pH value) and find your H3O+ concentration. Then you can set up an ice table and find the values at equilibrium and use those values to find the Ka value and pKa value.

Karan Thaker 2L
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Joined: Fri Sep 28, 2018 12:26 am

Re: pH vs pKa

Postby Karan Thaker 2L » Thu Jan 24, 2019 1:35 pm

If given pH, just take the inverse log of the pH and this will give you H30+ concentration. Follow steps on ice tables and determine other concentartions and you have your Ka value.

The main difference is that pKa is a logartithmic expression of Ka values and pH is a logarithmic expression of hydrogen ion conentration.

Posts: 69
Joined: Fri Sep 28, 2018 12:27 am

Re: pH vs pKa

Postby Katie_Duong_1D » Thu Jan 24, 2019 2:25 pm

pH is -log(H3O+ concentration). pka is -log(ka).

H3O+ concentration can be calculated by "undoing" the log. 10^-pH. From there, you can do an ICE table to find ka. ka is equilibrium concentrations for products over equilibrium concentrations for reactants.

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