Calculate the pH of a given solution sodium benzoate 005M ka

Calculate the pH of a given solution sodium benzoate 0.05M

k_a=6.3x10^-5

Solution

sdoium benzoate is salt of weak acid and strong base.

for such salts

pH = 1/2 [pKw + pKa + log C]

pKa = - log Ka = - log [6.3 x 10^-5]

pKa = 4.20

pH = 1/2 [14 + 4.20 + log 0.05]

pH = 8.45