Question

Calculate the pH of a solution that is 0.239 M acetic acid and 0.190 M sodium acetate. The Ka of acetic acid is 1.76×10–5 at 25°C. What is the pH of this mixture at 0°C? (At 0°C, Ka = 1.64x10-5)

Answer 1

Answer: The pH of the mixture at 0°C is 4.68

Step-by-step explanation:

To calculate the pH at 0°C, we use the equation given by Henderson Hasselbalch:

`pH=pK_a+\log(([salt])/([acid]))`

`pH=pK_a+\log(([CH_3COONa])/([CH_3COOH]))`

We are given:

`pK_a` = negative logarithm of acid dissociation constant of acetic acid at 0°C = 4.78

`[CH_3COONa]=0.190M`

`[CH_3COOH]=0.239M`

pH = ?

Putting values in above equation, we get:

`pH=4.78+\log((0.190)/(0.239))\\\\pH=4.68`

Hence, the pH of the mixture at 0°C is 4.68