Sebanyak 450 ml larutan NH3 0,5 M dicampur dengan 400 ml larutan HCL 0,4 M, jika kb NH3 = 10^-5, maka ph campurannya adalah.... a. 4 - log 4,1 b. 4 + log 4,1 c.

450 mL NH3 0,5 M + 400 mL HCl 0,4 M
Kb NH3 = 10^-5

pH campuran ... ?

n NH3 = M × V
n NH3 = 0,5 × 450
n NH3 = 225 mmol

n HCl = M × V
n HCl = 0,4 × 400
n HCl = 160 mmol

#Reaksi
..... NH3 + HCl => NH4Cl
M : 225 .. 160
R : .160 .. 160
___________---
S : . 65 .... --- ........ 160

[OH^-] = Kb × Basa lemah/Asam konjugasi
[OH^-] = 10^-5 × 65/160
[OH^-] = 10^-5 × 0,41
[OH^-] = 10^-6 × 4,1

pOH = - log [OH^-]
pOH = - log 10^-6 × 4,1
pOH = 6 - log 4,1

pH = 14 - pOH
pH = 14 - (6 - log 4,1)
pH = 14 - 6 + log 4,1
pH = 8 + log 4,1