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.

pH=pKa+log (conjugate baseweak acid)


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:

pKa=-logKa

Substitute in the Henderson-Hasselbalch equation:

pH=-log Ka+log (conjugate baseweak acid)

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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

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