Question

If you make up a solution of 150 ml 0.25 m tris in the acid form, what will be the ph? (tris fw: 121.14 g/mol, pka: 8.1)

a) pH 7.0
b) pH 8.1
c) pH 9.1
d) pH 10.1

Answer 1

The pH of a 0.25 M Tris buffer solution in the acid form with a pKa of 8.1 is 8.1, making option (b) the correct answer.

Step-by-step explanation:

The question at hand involves calculating the pH of a 0.25 M Tris buffer solution in its acid form. Tris (tris(hydroxymethyl)aminomethane) is often used in biochemistry and molecular biology as a component of buffer solutions. The pH of this buffer can be predicted using the Henderson-Hasselbalch equation:

pH = pKa + log([base]/[acid])

If we have Tris in its acid form, this means that the concentration of the conjugate base is negligible. Therefore, we can simplify the equation to:

pH = pKa

Given that the pKa of Tris is 8.1, we can deduce that the pH of the solution will also be 8.1 under these conditions. Hence, the correct option is:

b) pH 8.1