Page 66 - Modul Asam Basa

Contoh Soal

+
pH = - log [H ]
-3
pH = - log 2,121 x 10
pH = 3 - log 2,121

pOH = 14 – pH
pOH = 14 – (3 – log 2,121)

pOH = 11 + log 2,121

2. Berapa pH dan pOH larutan HCOOH 0,05 M bila derajat ionisasinya

3%!
Jawab:

-
+
HCOOH(aq) → HCOO (aq) + H (aq)
+
[H ] = Ma . α
+
[H ] = 0,05 x 3%
-2
+
-2
[H ] = 5 x 10 x 3 x 10
-4
+
[H ] = 15 x 10
-3
+
[H ] = 1,5 x 10
+
pH = - log [H ]
-3
pH = - log 1,5 x 10
pH = 3 - log 1,5
pOH = 14 – pH

pOH = 14 – (3 – log 1,5)
pOH = 11 + log 1,5

3. Tentukan pH larutan NH4OH 0,1 M bila derajat ionisasinya 0,014!

Jawab:
-
+
NH4OH(aq) → NH4 (aq) + OH (aq)
-
[OH ] = Mb . α
-
[OH ] = 0,1 x 0,014
-
-3
[OH ] = 1,4 x 10
-
pOH = - log [OH ]

E-MODUL KIMIA ASAM BASA 54