Question

Enter your answer in the provided box. Find the pH of a buffer that consists of 0.31 M boric acid (H3BO3) and 0.36 M sodium borate (NaH2BO3). (pKa of boric acid

Answer 1

pH = 9.30

Step-by-step explanation:

We can obtain the pH of a buffer using H-H equation:

pH = pKa + log [A⁻] / [HA]

Where pH is the pH of the solution,

pKa the pKa of the buffer (9.24 for boric acid)

[A⁻] the molarity of the conjugate base, NaH2BO3

[HA] molarity of the weak acid, H3BO3

Replacing:

pH = 9.24 + log [0.36M] / [0.31M]

pH = 9.30