Sapling 9

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IreneSeo3F
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Joined: Wed Sep 30, 2020 9:31 pm

Sapling 9

Postby IreneSeo3F » Sun Jan 24, 2021 9:54 pm

Why is the predominant species neutral if the pH value is less than the pKa value?

Rachael Cohen 3G
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Joined: Sun Dec 13, 2020 12:17 am

Re: Sapling 9

Postby Rachael Cohen 3G » Sun Jan 24, 2021 9:59 pm

At pH values below the pKa, the protonated species of HA will become more predominant. HA is neutral. A- is the only charged species in the solution.

JoshMoore2B
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Joined: Wed Sep 30, 2020 9:51 pm

Re: Sapling 9

Postby JoshMoore2B » Sun Jan 24, 2021 10:48 pm

IreneSeo3F wrote:Why is the predominant species neutral if the pH value is less than the pKa value?


Think of it this way:

pKa is a measure of a strength of an acid. When pH goes below pKa (that is, the acidity of the solution becomes stronger than the pKa), then the pKa won't be able to "compete" with the strength of the solution, and so it stays protonated and neutral.

Jaclyn Schwartz 1I
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Joined: Wed Sep 30, 2020 9:45 pm

Re: Sapling 9

Postby Jaclyn Schwartz 1I » Sun Jan 24, 2021 11:22 pm

If the pH goes below pKa, that means the acidity of the solution becomes stronger than the pKa. When this occurs, the protonated species of HA will become more predominant, HA becomes neutral and A- is charged.

Rose_Malki_3G
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Re: Sapling 9

Postby Rose_Malki_3G » Sun Jan 24, 2021 11:30 pm

This is because if the ph is lower than the pKa value it means that the surrounding solution is more acidic than the actual species, therefore it the species will not deprotonate and will remain neutral

Chinmayi Mutyala 3H
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Joined: Wed Sep 30, 2020 9:50 pm

Re: Sapling 9

Postby Chinmayi Mutyala 3H » Sun Jan 24, 2021 11:31 pm

If the pH is less, the solution the acid is in is more acidic so it won't deprotonate in the solution. The solution already has a high hydrogen ion concentration so it won't be able to add hydrogen ions easily which is why it remains neutral.

Alexis Sanft 1E
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Re: Sapling 9

Postby Alexis Sanft 1E » Sun Jan 24, 2021 11:31 pm

What does it mean to be a "predominant" species?

Alexis Sanft 1E
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Joined: Wed Feb 19, 2020 12:19 am

Re: Sapling 9

Postby Alexis Sanft 1E » Sun Jan 24, 2021 11:33 pm

Also, do we need to do any actual calculations if the pkA is given and the pH is given?

Ranen_Chang_2G
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Joined: Wed Nov 25, 2020 12:21 am

Re: Sapling 9

Postby Ranen_Chang_2G » Sun Jan 24, 2021 11:53 pm

Alexis Sanft 1E wrote:Also, do we need to do any actual calculations if the pkA is given and the pH is given?


To your questions, predominant species is the species where there is most of. In the acidic solution, the neutral HA is more. You do not need to calculate anything, just compare the values to each other.

MichaelRaad_1F
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Joined: Wed Sep 30, 2020 9:35 pm

Re: Sapling 9

Postby MichaelRaad_1F » Mon Jan 25, 2021 12:00 am

Alexis Sanft 1E wrote:What does it mean to be a "predominant" species?

I'm pretty sure it just means that there is more of it or it is the most basic/acidic in solution.

Nick Saeedi 1I
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Joined: Wed Sep 30, 2020 9:39 pm

Re: Sapling 9

Postby Nick Saeedi 1I » Mon Jan 25, 2021 5:22 pm

if the pH is less than the pKa the HA concentration is the highest so it will be neutral.


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