12.57, pH/pOH v. pKa/pKb

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Sydney Wu 2M
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Joined: Fri Jul 22, 2016 3:00 am

12.57, pH/pOH v. pKa/pKb

Postby Sydney Wu 2M » Wed Nov 30, 2016 11:17 am

Are pH=pKa and pOH=pKb? I am unsuccessfully trying to figure out why the answers the 12.57 are what they are. Part (a) gives tells that the pH of .10M HClO2 was measured to be 1.2 and asks us to to determine Ka and pKa. Isn't 1.2 the same as pKa?

Justin Folk 3I
Posts: 43
Joined: Wed Sep 21, 2016 2:56 pm

Re: 12.57, pH/pOH v. pKa/pKb

Postby Justin Folk 3I » Wed Nov 30, 2016 1:22 pm

No, pH is the measure of the [H+], while pKa is the measure of basically how much of a given acid HA dissociates.

They are related, though. While Ka value doesn't tell too much about H+ concentration (due to other things like diprotonations, 2 H+ / mol acid), if everything else is held constant, such as the initial HA concentration, and the number of protons/acid, the one with the higher Ka will have the higher acidity and therefore lower pH.

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