2. BUFFER:-
• A buffer solution is a solution which resists
changes in pH when a small amount of acid or
base is added.
3. NEED OF BUFFER :-
• they help to neutralize a reaction to a certain extent. Like
Acidic buffers are used to neutralize alkaline solutions.
• Blood acts as a buffer solution by keeping the pH at a
constant value.
• Rxns (reactions) in the body happen take place In the
blood plasma and these reactions might fail to happen if
the blood pH keeps changing. For a complete rxn to take
place, the pH must stay constant.
4. TYPES OF BUFFER :-
Generally buffers are of two types:-
1. Acidic buffer
2. Basic buffer
5. 1. ACIDIC BUFFER :-
• An Acidic buffer is a combination of weak acid and it’s salt with
strong base.
• i.e., Weak Acid & salt with strong base (conjugated base).
• Eg:- CH3COOH / CH3COONa
HCOOH / HCOONa
H2PO4 / NaHP2O4
6. 2. BASIC BUFFER :-
• A basic buffer is a combination of weak base and it’s salt
with a strong acid .
• i.e., weak base & salt with strong acid ( conjugated acid).
• E.g., NH3OH / NH4Cl
• NH3 / NH4Cl
• NH3 / (NH4)2CO3
7. PHOSPHATE BUFFERS :-
• Besides the two general types of buffers (i.e.- acidic and
basic ) , a third appears to exist .
• This is buffer system composed of 2 salts :-
1. Monobasic potassium phosphate (KH2PO4)
2. Dibasic potassiuam phosphate ( K2HPO4)
8. BUFFER ACTION:-
• The resistance of buffer solution to a change in pH is known as
buffer action.
• mechanism of buffer :-
9. BUFFER CAPACITY:-
• Buffer capacity (β) is defined as the moles of an acid or base necessary to
change the pH of a solution by 1, divided by the pH change and the
volume of buffer in liters; it is a unitless number. A buffer resists changes
in pH due to the addition of an acid or base though consumption of the
buffer.
Where,
• ∆n= amount of acid or buffer
• ∆pH = change in pH
10. APPLICATION OF BUFFER:-
1. Parental products mostly prepared the pH –of 7.4 (blood).
2. Opthalmic preparation (eye drops)- mostly ph of 7-8.
3. Topical preparation (skin products)
4. Physiology to maintain the blood pH levels – Kidney ,lungs, carbonic
anhydraze are the major organs responsible to maintain the blood pH level
(7.4).
5. Enabling drugs to be used in the human body: Injections are close to the
blood pH value; eye drops close to the eye environment.
