Ka Kb significance

Acidity
Basicity
The Conjugate Seesaw

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505166714
Posts: 50
Joined: Fri Sep 28, 2018 12:17 am

Ka Kb significance

Postby 505166714 » Fri Jan 18, 2019 8:25 am

What are the significance of Ka Kb and pKa pKb, why do we calculate them? What is the relationship between pH pOH and pKa pKb?

LedaKnowles2E
Posts: 62
Joined: Fri Sep 28, 2018 12:27 am

Re: Ka Kb significance

Postby LedaKnowles2E » Fri Jan 18, 2019 9:44 am

Ka*Kb=Kw=10^-14
pKa+pKb=14
and
[OH-][H3O+]=Kw=10^-14

Kevin ODonnell 2B
Posts: 62
Joined: Fri Sep 28, 2018 12:24 am

Re: Ka Kb significance

Postby Kevin ODonnell 2B » Fri Jan 18, 2019 9:48 am

So here is everything I have found
p in front of anything means -log, so
pKa = -log(Ka)
pKb = -log(Kb)
pH = -log(H+)
pOH = -log(OH-)

Other relationships
at 25 degrees C… pH + pOH = 14
Kw (1 x 10^-14) = Ka * Kb
pKa + pKb = 14 (this is a similar equation to the one above but by finding the -log we can deal with easier numbers like 14)

Definitions
pKa/pKb/Ka/Kb show us just how acidic or basic a solution is by describing the degree of ionization. PKa/Ka accounts for acids, while PKb/Kb accounts for our bases.
Kw is the ionization constant of water
pH/pOH helps to tell us if we are dealing with an acid or base by comparing the hydronium and hydroxide found in a solution

If you still need more help I found this website helped a lot:
https://www.thoughtco.com/ph-pka-ka-pkb ... ed-4027791

Jacob Bershatski 4C
Posts: 30
Joined: Fri Sep 28, 2018 12:21 am

Re: Ka Kb significance

Postby Jacob Bershatski 4C » Sun Jan 20, 2019 10:57 am

Ka and Kb are the equilibrium constants for the hydrolysis of acids and basis in water. The higher the Ka, the stronger the acid and the weaker its conjugate base. The higher the Kb, the stronger the base and the weaker its conjugate acid. pKa and pKb are just a simplified way to represent this.


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