Acidity & Basicity Constants

[Bailey Herbert 2L]

What do acidity and basicity constants actually represent? Is it an equilibrium of sorts?

[Kurosh Zamiri 1I]

Yes, acidity and basicity constants do represent an equilibrium. Ka represents the equilibrium constant of a weak acid, while Kb represents the equilibrium constant of a weak acid. The products of these two is equal to the Kw, which is the dissociation constant of water. Since the value of Kw is 1*10^-14, this establishes a proportionality relationship between Ka and Kb. When Ka increases, Kb decreases, and vice versa. Hope this helps!

[Ella Henrickson 3I]

Ka and Kb represent the equilibrium constants for weak acids and bases that don't completely dissociate. Also, the have an inverse relationship, so using the equation ka x Kb = 10^-14, you can find the equilibrium constants for conjugate acids and bases (this is detailed in the January 12th lecture, where Dr. Levelle talks about the "conjugate seesaw"). Hope this helps :)

[Sevde Coban 2J]

Acidity and basicity constants represent the capacity of molecules to donate or accept protons. For example, a small acidity constant implies that only a small proportion of a certain molecule will donate their protons when dissolved in water.

[KPINTO 1B]

Hi! Just to add on, the reason why a Ka and Kb exist is because of acid-base equilibrium that occurs from weak acids and bases. You will never use a Ka or Kb with a strong acid like HBr or a strong base like NaOH because we assume these dissociate completely and we do not need to set up an ice box and there is no equilibrium. It is a one way arrow for these rather for the other one it is a two way equilibrium arrow, so you need the equilibrium constants and Ka and Kb are just specialized equilibrium constants for acidic or basic equilibriums. We use Ka when H3O+ is a product and we use Kb when OH- is a product.

[Grace_Wu]

Ka and Kb are the acidity and basicity constant for weak acids and bases, since they are not completely deprotonated or protonated. Ka*Kb=Kw, 10^-14.

[dericasu3a]

Ka and Kb represent the acidity and basicity constants for weak acids and bases, respectively. The product of the two is Kw which is equal to 10e-14 so they are inversely related.