Relative Strengths of Acids and Bases

HA

________ must be a weaker acid than H3O+ and, A- must be a STRONGER base than water.

strength of an acid

The ________ is measured by the extent to which it forms H3O+ in water.

strength of a base

The ________ is measured by the extent to which it forms hydroxide ions in water.

Weak acids

________ are only slightly ionized.

Ka values

________ are related to the strength of the acids.

HA(aq)    +    H2O(l)     ⇌ H3O+(aq)    +    A

(aq)

Acid ionization constant (Ka)

the equilibrium constant for an acid

Base ionization constant (Kb)

the equilibrium constant for a base

HA must be a weaker acid than H3O+ and,  A

must be a STRONGER base than water

Kb =

([HB+][OH-])/[B]

Ka =

([H+][A-])/[HA]

The larger the Ka,

the stronger the acid

The smaller the Ka,

the weaker the acid

The larger the Kb,

the stronger the base

The smaller the Kb,

the weaker the base

The stronger the acid,

the WEAKER its conjugate base.