Sebanyak 50ml larutan HNO2 0,1 direaksikan 50ml KOH yang molaritasnya 0,1M jika Ka HNO2= 5x10^-4 maka ph campuran adalah

mol HNO2 = 50 x 0.1 = 5 mmol
mol KOH = 50 x 0.1 = 5 mmol

.....HNO2 + KOH <=> KNO2 + H2O
m 5...............5.................-.............-
r -5..............-5...............+5.........+5
s -..................-..................5............5

habis bereaksi, terjadi hidrolisis garam.
[garam] = mol garam/v total = 5/100 = 0.05
[OH-] = akar kw/ka . [garam]
[OH-] = akar 10^-14/5x 10^-4 x 0.05 = 10^-6
pOH = 6
pH = 14-6 = 8