Page 68 - Pharmaceutical_Analytical_Chemistry_1_Theoretical_Notes_Level_1

Mansoura National University
Pharm D-Clinical Pharmacy Program Level 1 Pharm. Anal. Chem. 1 (PC 101)

pH Problem Solving Diagram

Quiz

-
The pH of a solution is 3.0. What is the [OH ]?
Solution:

pOH= pK - pH
w

pOH= 14 – 3.0 = 11
-11
-
[OH ] = 1 x 10 M
- +
What is the [OH ] of a solution whose [H ] = 0.001M?

Solution:
-3
+
[H ] = 0.001 = 1 x 10 M
1  10 − 14 -11
-
[OH ] = = 1 x 10 M
1  10 − 3
-9
If the dissociation constant of pyridine is 1.71 x 10 . Calculate the dissociation
+
constant of its conjugate acid. (the conjugate acid is C 6H 5 NH )
Solution:

K K = K
a b w

-9 -14
1.71 x 10 x K = 1 x 10
a
-14 -9 -6
K = 1 x 10 /1.71 x 10 = 5.85x 10
a

63