lecture 6 question

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Funmi Baruwa
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lecture 6 question

Postby Funmi Baruwa » Fri Jan 22, 2021 6:40 am

In lecture 6, Dr. Lavelle included this example

"What id the pH and percentage ionization of acetic acid in 0.1 M of CH3COOH?"

My question is from reading this question, how were we supposed to know we were solving for the pH of the solution (-log[H3O+]), and not for the pH of CH3COOH?

Marylyn Makar 1B
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Re: lecture 6 question

Postby Marylyn Makar 1B » Fri Jan 22, 2021 9:26 am

Hi! So the question asks what the pH is for acetic acid. In order to find the pH, we must first find the concentration of H30 + because the definition of pH is -log [H30+]. When you find the concentration of [H30+] at equilibrium, you are then able to find the pH of the acetic acid.

Sreeram Kurada 3H
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Re: lecture 6 question

Postby Sreeram Kurada 3H » Fri Jan 22, 2021 9:46 am

Also the ka or kb must be given for you to set up the ice table. With that given you could solve for x and could get the concentrations of H+ ions, which you would -log to get the ph. Also, if you wanted to find the percent ionization, you would place (x/HA) * 100.

Funmi Baruwa
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Joined: Wed Sep 30, 2020 9:50 pm

Re: lecture 6 question

Postby Funmi Baruwa » Thu Jan 28, 2021 1:26 pm

oh so basically it would explicitly state whether it was asking for pH or pOH?

Andersen Chu 2H
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Re: lecture 6 question

Postby Andersen Chu 2H » Thu Jan 28, 2021 3:44 pm

how were we supposed to know we were solving for the pH of the solution (-log[H3O+]), and not for the pH of CH3COOH?

^ The pH of the solution (-log[H30+]) is the pH for the solution with CH3COOH in it. These are basically the same because there is no pH = (-log[CH3COOH]).

Also yes, they would explicitly ask for pH or pOH in the problem, as he does in the beginning of this question


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