For the titration of a weak acid with a strong base what is the pka of the weak acid if the ph is 6.72 at the equilvalence point (100% t), 9.12 at the end point, and 4.23 at 50% t? answer with one sig fig.

Explanation:

We have to calculate value.

It is known that at the equivalence point concentration of acid is equal to the concentration of anion formed.

Hence,         [HA] =

Now, relation between and pH is as follows.

                   pH =

Putting the values into the above formula as follows.

                   pH =

                  4.23 =            (as [HA] = )

                    = 4.23                (as log (1) = 0)

or,                   = 4

Thus, we can conclude that of given weak acid is 4.