Question

Can someone explain why these answers are correct? I don't understand this. Thanks.

4) What is the effective pH range of buffers formed with the following acids? a) Hydrofluoric acid pka = 3.17 effective buffer range 2.17 to 4.17 b) Acetic acid pKa = 4.74 effective buffer range 3.74 to 5.74 c) Ammonia pKb = 4.75 pKa = 9.25 effective buffer range 8.25 to 10.25

Answer 1

A buffer solution is one which can resist change in its pH on the addition of an acid or a base.

Calculation of pH of buffer solution:

1.Buffer solution of a weak acid and its salt:(Henderson - Hasselbalch equation

i. e., the calculations of pH of a buffer solution made by mixing known quantities of a weak acid and its salt)

pH = pK_a + log ([salt] /([acid])

2.Buffer solution of a weak base and its salt

pOH = pK_b +log([salt]) /([base])