Question

Berapakah Gram NaOH (Mr=40) yang dimasukkan kedalam 100mL larutan CH3COOH 0,1M agar diperoleh larutan penyangga dengan pH=5 (Ka CH3COOH = 10^-5)

Tolong yaa
Untuk Ujian

Answer 1

Mmol CH3COOH = 100 x 0,1 = 10 mmol
mmol NaOH = x mol
CH3COOH + NaOH => CH3COONa + H2O
a : 10              x
b :  x              x                x                x
s : 10-x            -                x                x

pH = 5
pH = - log[H+]
5 = - log [H+]
[H+] = 10⁻⁵

[H+] = Ka x mmol asam/mmol garam
10⁻⁵ = 10⁻⁵  x 10-x / x
x = 10 - x
2x = 10
x = 5
mmol NaOH = 5 mmol
massa NaOH = 5 mmol x 40 mg/mmol = 200 mgram = 0,2 gram