Acid base titration

1. ACID BASE TITRATION
BY: HIMANSHU RAJPUROHIT
DETACHMENT OF PH. ANALYSIS

2. INTRODUCTION
• Acid base titration is base upon the neutrailization reaction
between acid and base. Therefore it is also called neutralization
titration In acid base titration, the standard solution having
know concentration of acid is titrated against the unknows
concentration of base or vice versa.
• In neutrailization reaction salt and water form
• NaOH + HCL NaCL + H2O

3. CONCEPT OF ACID BASE
• 1. Arrhenius acid base theory
• 2. Bronsted-Lowry proton theory
• 3. Lewis electron theory

4. 1. ARRHENIUS ACID BASE THEORY
• According to Arrhenius concept acid is substance which gives
hydrogen (H+)ion in water.
• HCL H+ + Cl-
• According to Arrhenius concept base is substance which gives
hydroxyl (OH) ion in water.
• NaOH Na+ + OH -

5. 2.BRONSTED-LOWRY PROTON THEORY
• According to Bronsted lowry concept acid is a chemical which
gives proton (H+)in solvent.
• HCL H+ + Cl-
• According to Bronsted lowry concept base is a chemical which
accept proton (H+)in solvent

6. 3. LEWIS ELECTRON THEORY
• According to lewis concept acid is a substance which accept
electron pair to form a coordination bond.
• Eg. H+, NH4+
• According to lewis concept base is a substance which give
electron pair to form a coordination bond.
• Eg. NH3, OH-

7. THEORIES OF ACID BASE INDICATOR
• Acid base indicator is a chemical which determine the end point
in neutralization titration by changing color according to pH of
titration solution.
• 1. Ostwald theory
• 2. Resonance theory

8. 1. OSTWALD THEORY
• Acid base indicator is either a weak acid or a weak base having
different color in ionized and unionized forms.
• Phenolphthalein is a weak acid it show pink color in basic
medium and is colorless in acidic medium.
• Methyl orange is a weak base is pink color in acidic medium
and yellowish color orange in basic medium.

9. 2. RESONANCE THEORY
• Acid base indicator is organic compound and exists in 2
tautomeric forms
• 1. Benzenoid
• 2. Quinonoid
• Eg Phenolphthalein in acid solution: Quinonoid form change
into benzenoid form to show the lighter of color of the
indicator (colourless)
• Phenolphthalein in base solution benzenoid form changes into
quinonoid form to show the darker colour of indicator (pink)