Question

A buffer is prepared by adding 20.0 g of sodium acetate to 480 ml of a 0.160 m acetic acid solution. determine the ph of the buffer. the ka of acetic acid is 1.8 x 10-5

Answer 1

Hello!

The chemical reaction for the dissociation of Acetic Acid is the following:

CH₃COOH + H₂O ⇄ CH₃COO⁻ + H₃O⁺

To solve the problem we are going to use the Henderson-Hasselbach Equation, as follows, but first we need to know the pKa:


`pKa=-log(Ka)=-log( 1,8*10^(-5) )=4,74`


`pH=pKa + log( ([CH_3COO^(-) ])/([CH_3COOH]) )`


`pH=4,74+log( ((20 g CH_3COONa )/(0,480 L)* (1 mol CH_3COONa)/(82,03 g CH_3COONa) )/(0,160 M) )=5,24`

So, the pH of this solution is 5,24

Have a nice day!