The ka of acetic acid is 1.76 × 10-5. the ph of a buffer prepared by combining 50.0 ml of 1.00 m potassium acetate and 50.0 ml of 1.00 m acetic acid is

pH = 4.75

Explanation:

Given:

Ka(acetic acid, CH3COOH) = 1.76*10^-5

Volume of CH3COOK = 50.0 ml

Molarity of CH3COOK = 1.00 M

Volume of CH3COOH = 50.0 ml

Molarity of CH3COOH = 1.00 M

To determine:

pH of the above buffer solution

Calculation:

The pH of a buffer is related to the concentrations of the conjugate base and acid via Henderson - Hasselbalch equation:

where pKa = -logKa

{A-] = conjugate base

[HA] = acid

For the CH3COOH/CH3COOK buffer:

here, [CH3COOK] = [CH3COOH], therefore,