Question

Ke dalam 500 ml larutan CH3COOH 0,1 M ditambahkan CH3COOK sehingga pJ campuran menjadi 5. bila Ka CH3COOH = 2x10^-5 maka banyaknya CH3COOK yg dimasukkan adalah... (Ar. C =12 H=1 O=16 K=39) Plis bantu!! Thanks before!!

Answer 1

Diketahui :
Volume larutan CH3COOH = 500 ml = 0,5 L
Molaritas CH3COOH = 0,1 M = 0,1 mol/L
pH campuran = 5
Ka CH3COOH = 2 × 10^-5
Ar C = 12 , H = 1 , O = 16 , K = 39

Ditanya : Banyaknya CH3COOK yang dimasukan ?

Jawab :

n CH3COOH :
= M . V
= 0,1 mol/L . 0,5 L
= 0,05 mol

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

n garam CH3COOK :
= Ka . n asam / [H+]
= 2 × 10^-5 . 0,05 mol / 10^-5
= 0,1 mol

Mr CH3COOK :
= 2.Ar C + 3.Ar H + 2.Ar O + Ar K
= 2.12 + 3.1 + 2.16 + 39
= 24 + 3 + 32 + 39
= 98 gram/mol

massa CH3COOK yang dimasukan :
= n . Mr
= 0,1 mol . 98 gram/mol
= 9,8 gram