Question

A buffer contains the weak acid HA and its conjugate base A−. The weak acid has a pKa of 4.82 and the buffer has a pH of 4.25. Then, [HA] > [A^-]. True or False?

Answer 1

True

Step-by-step explanation:

Given:

pKa of weak acid = 4.82

pH of buffer = 4.25

Now, put the values in Henderson-Hasselbalch equation

`pH=p_(Ka) + log([Salt])/([Acid])`

`4.25=4.82 + log([A^(-)])/([HA])`

`log([A^(-)])/([HA]) = -0.57`

`([A^(-)])/([HA]) = 0.269`

0.269 is less than 1.

therefore, [HA] is greater than [A-].

Hence, the given statement is true.