Question

Which of the following buffers will have the best buffer capacity?

a. A solution containing 0.157 M H2PO4- and 0.189 M HPO42-

b. A solution containing 0.043 M H2PO4- and 0.025 M HPO42-

c. A solution containing 0.101 M H2PO4- and 0.101 M HPO42

d. They all have the same buffer capacity

Answer 1

Ans- Buffer C

Explanation-

We know a buffer is a solution where both a weak acid (here H2PO4-) and its conjugate base (here HPO4 2-) are present.

Now the more closer the amount of acid and conjugate base present to each other, the better is the buffer

Or in other words, we can say the closer the value of ratio of base : acid to 1, the better is the buffer.

So for the given buffers-

a) base : acid = 0.157 : 0.189 = 0.83

b) base: acid = 0.043 : 0.025 = 1.72

c) base:acid = 0.101 : 0.101 = 1

So here buffer C is the best buffer. Thus has the best buffer capasity