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pH Buffer Isotonic Solution - Coggle Diagram
pH Buffer Isotonic Solution
-log10
pH = -log10 [H+]
Sorensen's pH scale -1 to 14
1 to 5 - Acidic
7- Neutral
8 to 14 - Alkaline
Electrometric determination - Potentiometric ( discription of pH)
Colorimetery (pH meter)
Buffer solution
The solution that resist change in pH after addition of small quantity of acid or base
Types
Basic
-Weak Base
Conjugate salt of strong base
Combination of acid and base
Two salts (acid base pair exchange)
Acidic
-Weak Acid
Conjugate salt of strong acid
Buffer action
The ability of buffer to resist change in pH upon addition of small amount of acid or base
Equation
β = d(B)/ d (pH)
d (B) - equivalence of strong acid or base
d(pH) - Change in pH
Larger the buffer capacity more resistant the buffer for change in pH and vice versa
Buffer Capacity -
Quantitative, amont of acid or base required to change pH of 1 litre buffer by 1 unit
Application
Solubility - increased at particular pH
Example - Ferric Ion, Phosphates, Borates in acidic medium
Color of raspberry syrup maintain at acidic pH
Stability- adrenaline at
2.5 to 5 pH,
Sodium thiosulphate in alkaline, sodium metabisulphate
Activity - sodium hypochlorite germicidal effect is more at lower pH
To prevent irritations in parent drug
Classification
Biological buffer
Pharmaceutical buffer
Buffer equation / Henderson - Hasselbach
equation
pH = pka log base/acid
Application
Determine pH of solution.
Amount if unionized
molecule.
pka
Solubility at any pH.
Selection of salt for preparation of suitable pH buffer.