The ka values for several weak acids are given below. which acid (and its conjugate base) would be the best buffer at ph = 8.0?

Tris and its conjugate base would be the best buffer at pH 8.

Further Explanation:

Buffer solution:

The solutions that oppose any change in their pH on addition of small amounts of acid or base are called buffer solutions. These are formed wither by a weak base and its conjugate acid or a weak acid and its conjugate base.

Henderson-Hasselbalch equation for a buffer solution is as follows:

    …… (1)                                                        

A buffer is most effective when the concentration of both acid and its conjugate base is the same. So equation (1) then modifies as follows:

  …… (2)                                                                            

Therefore a buffer works best if its pH becomes equal to .

The formula to calculate is as follows:

 …… (3)                                                            

Here, is the dissociation constant of acid.

Substitute for in equation (3) to calculate of tris.

Substitute for in equation (3) to calculate of MES.

Substitute for in equation (3) to calculate of acetic acid.

Substitute for in equation (3) to calculate of formic acid.

Substitute for in equation (3) to calculate of HEPES.

The value of of tris is nearly equal to the required pH. So tris along with its conjugate base would be the best buffer at pH 8.

Learn more:

Write the chemical equation responsible for pH of buffer containing   and  :

Reason for the acidic and basic nature of amino acid.

Answer details:

Grade: High School

Chapter: Acid, base and salts

Subject: Chemistry

Keywords: tris, acetic acid, formic acid, MES, HEPES, pH, pKa, Henderson, best buffer, 7.49, 8.20, 4.74, 3.74, Ka.

answer: mercury

explanation: