Weaker Base, Higher pKb

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Michelle N - 2C
Posts: 117
Joined: Wed Sep 18, 2019 12:19 am

Weaker Base, Higher pKb

Postby Michelle N - 2C » Sun Feb 02, 2020 1:16 am

Hello! I saw that during the lecture (this was from like week 2), Dr. Lavelle mentioned that the weaker the base, the higher its Kb value is, which is seen when he compared two different Kb values. Although I feel like I understand that, I'd like to know if there were any key conceptual points that I missed about when I was writing this down. Can someone explain to me the concept of why this came to be, if any? Thank you!

Megan Cao 1I
Posts: 103
Joined: Sat Sep 07, 2019 12:18 am

Re: Weaker Base, Higher pKb

Postby Megan Cao 1I » Sun Feb 02, 2020 9:58 am

the equilibrium constant is calculated as products/reactants. since weak acids/bases only slightly dissociate in water, they'd only form a bit of products. Whereas for strong acids/bases they would completely dissociate, where products >> reactants. from the Kb, the greater the value, the lower the pkb, and the stronger the base. (and vice versa)

Veronica Lu 2H
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Re: Weaker Base, Higher pKb

Postby Veronica Lu 2H » Sun Feb 02, 2020 2:47 pm

the bigger the kb, the lower the pkb (log properties) which also means the stronger the base

KBELTRAMI_1E
Posts: 108
Joined: Sat Jul 20, 2019 12:17 am

Re: Weaker Base, Higher pKb

Postby KBELTRAMI_1E » Sun Feb 02, 2020 3:01 pm

Veronica Lu 2H wrote:the bigger the kb, the lower the pkb (log properties) which also means the stronger the base


so then did Lavelle mean to say that the higher the kb, the stronger the base? because the original post here says that he stated that the higher the kb, the weaker the base. now I'm confused.

MTanikella_1K
Posts: 110
Joined: Sat Jul 20, 2019 12:16 am

Re: Weaker Base, Higher pKb

Postby MTanikella_1K » Sun Feb 02, 2020 6:16 pm

Lower pKb indicates a stronger base. We know that pKb is the -log(Kb) so if the value of Kb is large, pKb will be lower. The greater the value of Kb, the lower the value of pKb (stronger base).


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