conjugate seesaw

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Rhea Shah 2F
Posts: 97
Joined: Thu Jul 25, 2019 12:17 am

conjugate seesaw

Postby Rhea Shah 2F » Sun Jan 19, 2020 4:57 pm

Could someone explain the reasoning behind the conjugate seesaw?

JamieVu_2C
Posts: 108
Joined: Thu Jul 25, 2019 12:16 am

Re: conjugate seesaw

Postby JamieVu_2C » Sun Jan 19, 2020 5:10 pm

[H3O+][OH-] = 10^-14
For this equation if the concentration of H3O+ is large, then the concentration of OH- must be low since their product is always a constant at 10^-14, and vice versa.

pKa + pKb = pKw
Similarly, if pKa is large, then pKb is low since their sum always equals pKw, which is 14, and vice versa for pKb.

Eugene Chung 3F
Posts: 142
Joined: Wed Nov 15, 2017 3:03 am

Re: conjugate seesaw

Postby Eugene Chung 3F » Sun Jan 19, 2020 5:18 pm

To give an example, When HCl (strong acid) dissociate in aqueous solution, than the conjugate base is Cl-, an ion produced as a result of HCl's dissociation. It can technically accept protons to produce acid in reverse direction but because HCl is strong, and dissociates completely, the reaction only occurs forward. So, strong acid produce weaker conjugate base that is unlikely to accept proton and produce acid again. (and vice versa for strong base).

Rosa Munoz 2E
Posts: 105
Joined: Wed Sep 18, 2019 12:21 am

Re: conjugate seesaw

Postby Rosa Munoz 2E » Sun Jan 19, 2020 5:25 pm

Since it is equal to a constant, if one goes down, the other must go up.

Shail Avasthi 2C
Posts: 101
Joined: Fri Aug 30, 2019 12:17 am

Re: conjugate seesaw

Postby Shail Avasthi 2C » Sun Jan 19, 2020 5:31 pm

Ka x Kb = Kw
Kw is a constant (10^-14)
If Ka is high for a strong acid, Kb must therefore be low because their product is equal to a constant. And vice versa: if Kb is high for a strong base, then Ka must therefore be low.


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