Titration of chemicals hazards

1. Redox Titration
DR: KAREEM MOHAMED

2.  The potentiometer is an instrument used for measuring the unknown voltag
by comparing it with the known voltage.
is a analytical method to determine the concentration of a provided
analyte by triggering a redox reaction between the titrant and provided
analyte of unknown conc. These types of titrations sometimes require the
use of a potentiometer or a redox indicator.
 The end point of such titrations can be determined by either a
colour changing indicator or a potentiometer.
 Redox titration:

3. Loss of Electrons is Oxidation (LEO)
Na Na+ + e-
Positive charge represents electron deficiency
ONE POSITIVE CHARGE MEANS DEFICIENT BY ONE ELECTRON
What is oxidation?

4. What is reduction?
Cl + e-
Negative charge represents electron richness
ONE NEGATIVE CHARGE MEANS RICH BY ONE ELECTRON
Cl -
eduction ( )
Gain of letrtion is R GE
R
E

5. Determination of ferrous iron (Fe2+ )
Fe2+  Fe3+ + e
By direct titration using an oxidizing agent as KMnO4 in acid medium of
H2SO4.
MnO4
- + 5Fe2+ + 8H+  Mn2+ + 5Fe3+ + 4H2O
No indicator is used where MnO4
- is self-indicator.
During the titration; the color of permanganate change from purple to
colorless.
At the End point; when all Fe2+ converted to Fe3+, excess drop of
KMnO4 give pink color.
By using potassium permanganate
KMnO4:

7. Buffers
 Buffers are the solutions which resist changes in pH when small
amounts of acid or alkali is added to them.
 Buffers are of main importance in regulating the pH of the body fluids
and tissues.
 Many biochemical reactions including those catalyzed by enzymes
require pH control which is provided by buffers.

8.  Making an Acidic Buffer Solution:
It must contain significant amounts of both a weak acid and its
conjugate base.

9. Acidic Buffers
As the name suggests, these solutions are used to maintain acidic
environments. Acid buffer has acidic pH and is prepared by mixing a
weak acid and its salt with a strong base. An aqueous solution of an
equal concentration of acetic acid and sodium acetate has a pH of 4.74.
 pH of these solutions is below seven
 These solutions consist of a weak acid and a salt of a weak acid.
 An example of an acidic buffer solution is a mixture of sodium acetate
and acetic acid (pH = 4.75).
 Types of Buffer Solution:

10. Alkaline Buffers
These buffer solutions are used to maintain basic conditions. Basic buffer
has a basic pH and is prepared by mixing a weak base and its salt with
strong acid. The aqueous solution of an equal concentration of
ammonium hydroxide and ammonium chloride has a pH of 9.25.
 The pH of these solutions is above seven
 They contain a weak base and a salt of the weak base.
 An example of an alkaline buffer solution is a mixture of ammonium
hydroxide and ammonium chloride (pH = 9.25).

11.  Mechanism of Buffering Action
In solution, the salt is completely ionized and the weak acid is partly ionized.
• CH3COONa ⇌ Na+ + CH3COO–
• CH3COOH ⇌ H+ + CH3COO–
 On Addition of Acid and Base
• On addition of acid, the released protons of acid will be removed by the acetate ions
to form an acetic acid molecule.
H+ + CH3COO– (from added acid) ⇌ CH3COOH (from buffer solution)
• On addition of the base, the hydroxide released by the base will be removed by the
hydrogen ions to form water.
HO– + H+ (from added base) ⇌ H2O (from buffer solution)

14. Name of
indicator
‫المشعرات‬
‫العالمية‬
‫ڤثالي‬ ‫الڤنول‬
‫ن‬
‫المثيل‬
‫البرتقالي‬
‫االحم‬ ‫الڤينول‬
‫ر‬
‫ثيمول‬ ‫البرومو‬
‫االزرق‬
‫حامضي‬
‫متعادل‬
‫قاعدي‬