Question

How do you make a buffer with an assigned pH and concentration? To answer the question, please provide a step-by-step outline.

Answer 1

A buffer solution is basically a mixture of a weak acid and its conjugate base or a mixture of a weak base and its conjugate acid, whose pH changes very little when acid or base is added to it.

To make a buffer Solution, there are different ways

1st:
1. The acid form of the buffer is added to 60% of the total volume of water
2. pH is measured.
3. pH is adjusted using a strong conjugate base and desired conc. is obtained.

2nd:

1. Both the acid solution and the base solution is prepared of conc. same as buffer conc.
2. They are added while monitoring pH of the entire buffer.
3. And desired conc is obtained.

3rd:

Using the equation of Henderson-Hesselbach,

that is,

pH= pK_a + log { [conjugate base]/[weak acid] }

the conc of the weak acid and its conjugate base is determined for desired buffer pH.