# Question #2109a

##### 1 Answer

Start with the dissociation of the ethanoic acid,

The *acid dissociation constant*,

When in aqueous solution, the ethanoate ion, which is the conjugate base of ethanoic acid, reacts with water to reform ethanoic acid and produce hydroxide ions.

The *base dissociation constant*,

Notice that both equations contain a form of the weak acid - conjugate base ratio. This means that you can use this ratio to determine a relationship between the concentration of hydronium ions, that of hydroxide ions, and the two dissociation constants.

Since

Plug this into the equation for

Now take a look at the equation for the *self-ionization of water*

The *ionization constant* of water is known to be

Plug this into equation

For conjugate acid/base pair, the product of the two dissociation constants is equal to the *ionization constant* of water.