Temen2 bantu jawab soalnya ya:)

100 cm^3 CH3COOH 0,1 M + CH3COONa padat
pH = 5
Ka CH3COOH = 10^-5
Mr CH3COONa = 82

Massa CH3COONa ... ?

*n CH3COOH 0,1 M

V = 100 cm^3 = 100 mL = 0,1 L

n CH3COOH = M × V
n CH3COOH = 0,1 × 0,1 L
n CH3COOH = 0,01 mol

*n CH3COONa padat
n CH3COONa = gram/Mr
n CH3COONa = x/82
n CH3COONa = (x/82) mol

*pH = 5
- log [H^+] = 5
[H^+] = 10^-5

*[H^+] = Ka × n asam lemah/n basa konjugasi
10^-5 = 10^-5 × 0,01 / (x/82)
x/82 = 0,01
x = 0,01 × 82
x = 0,82 gram

Jadi, massa natrium asetat yang ditambahkan adalah 0,82 gram.