Suatu larutan penyangga yang terdiri dari campuran CH3COOH 0,01 M (Ka=10-5) an CH3COONa 0,15 M mempunyai pH sebesar 6. berapakah perbandingan volume CH3COOH : CH3COONa pada larutan tersebut?
A. 5:1
B. 2:1
C. 1:2
D. 2:3
E. 3:2

2

Jawabanmu

2014-06-23T13:25:38+07:00
                   CH3COOH + NaOH -> CH3COONa + H2O
pH = 6
[ H+] = 10⁻⁶
rumus umum penyangga / buffer itu =
[ H+] = Ka.Ma
                 G
10⁻⁶= 10⁻⁵ x Ma.Va/Mg.Vg
10⁻⁶ = 10⁻⁵ x 0.01.Va/0.15.Vg ( dibagi 0.05 )
10⁻⁶ = 10⁻⁵ x 0.2 Vol.asam/3 Vol.garam
3.10⁻⁶ Vol.garam = 2.10⁻⁶ Vol Asam
Vol.Asam =     3
Vol.Garam       2
12 3 12
sebenernya asal rumusnya darimana sih kak?
coba jawab
2014-06-23T19:49:10+07:00
PH=pKa - (log [mol (CH3COOH)] - log [mol(CH3COONa)])
6 = 5 - (log ([CH3COOH]xV CH3COOH) - log ([CH3COONa]xV CH3COONa))
-log ([CH3COOH]xV CH3COOH) + log ([CH3COONa]xV CH3COONa)=1
-log (mol CH3COOH / mol CH3COONa)=1
mol CH3COOH / mol CH3COONa = 10^-1 = 0.1
[CH3COOH] x V CH3COOH= 0.1 x ([CH3COONa] x V CH3COONa)
0.01 M x V CH3COOH = 0.1 x (0.15 M x V CH3COONa)
V CH3COOH / V CH3COONa = 0.015 M / 0.01 M = 3/2                            (Huruf 'M'dicoret)
Jadi perbandingan Volume CH3COOH / Volume CH3COONa adalah sama dengan 3:2