# Problem: Calculate the pH of a buffer that is 0.058 M HF and 0.058 M LiF. The Ka for HF is 3.5 x 10-4. A) 9.31 B) 2.86 C) 4.69 D) 3.46 E) 10.54

###### FREE Expert Solution

Henderson-Hasselbalch equation.

Given solution:

HF is a weak acid
the anion in KF is the conjugate base

▪ F- → anion  conjugate base

- concentration of F- = concentration of KF

• The solution is composed of a weak acid and its conjugate base, therefore we have a buffer.

We can use the Henderson-Hasselbalch Equation to solve for pH.

Recall:

${\mathbf{pK}}_{\mathbf{a}}\mathbf{=}\mathbf{-}\mathbf{log}\mathbf{ }{\mathbf{K}}_{\mathbf{a}}$

Substitute in the Henderson-Hasselbalch equation:

###### Problem Details

Calculate the pH of a buffer that is 0.058 M HF and 0.058 M LiF. The Ka for HF is 3.5 x 10-4

A) 9.31

B) 2.86

C) 4.69

D) 3.46

E) 10.54