Page 15 - PC 101 Interactive practical book

MANSOURA NATIONAL UNIVERSIY
PHARM D- CLINICAL PHARMACY LEVEL I PHARM. ANAL. CHEM. I (PC 101)

Acid-Base Titrations

It's a type of titrations that involve reactions between acids and bases.

Remember: ▪ pH = - log [H ] ……………[H ] means the molar concn. of H .
 + + +
▪ pH > 7  basic, pH =7  neutral, pH < 7  acidic.

Acid-base indicators:

♦ They are indicators used to indicate the end point of acid-base titrations (i.e.

indicate the completeness of the reaction by changing their colors).

♦ Each indicator has its specific {pH range} which is the range of pH within

which the indicator changes its color.

Examples of acid-base indicators:

1. Methyl Orange (M.O.):

 pH range ≈ (3 – 4.5) approximately.

 We use 2-3 drops of it in our experiments.

 Color:

Red Orange Yellow

pH  0 3 4.5 14

  
Acidic E.P. Basic

to M.O. by M.O. to M.O.

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