The document provides an overview of reduction and reducing agents in chemistry, defining reduction as the gain of electrons and describing reducing agents as substances that can donate electrons. It highlights the identification of reducing agents through oxidation states, lists common reducing reagents, and discusses their applications in various industries, organic chemistry, and analytical chemistry. Additionally, it explains the role of reducing agents in processes like photosynthesis and metal extraction.

1. REDUCTION AND
REDUCING AGENTS
Outline
Definition
Identification
Position in periodic table
Examples

2. PRESENTED TO:
MAM RUBINA
MUKHTAR

3. REDUCTION
 REDUCTION is a process in which a
chemical substance changes because of
the removal of oxygen.e.g
 Cl + e⁻ → Cl⁻
 Reduction is the gain of electrons
during a chemical reaction by an
atom,molecule or ion.
 Reduction occurs when oxidation state
of an atom,molecule or ion is
decreased.

4. REDUCING REAGENTS
 A reducing reagent is a substance
that has the ability to reduce other
substances.
 The reagents lose electrons and are
oxidized in a chemical reaction.
 In organic chemistry Reduction
specifically refers to addition of
hydrogen to a molecule.

5.  Basically in a chemical reaction
reducing reagent is that one
having more no. of electrons
comparitively to other reactant
which it can donate and oxidizes
itself.

6. GOOD REDUCING AGENTS
 Good reducing agents are those having
low electronegetivity and comparitively
low ionization energies.
 An atom with a relatively large atomic
radius tends to be a better reductant.

7. EXAMPLE
 Zn + Cu²ᶧ→ Zn²ᶧ + Cu
 Reduction Half Reaction:
Cu²ᶧ→ Cu
Copper ion is gaining electrons so is reduced
to copper metal.
 Oxidation State: is changed from +2 → 0
Hence Cu is oxidizing agent.

8. Oxidation Half Reaction:
Zn → Zn²ᶧ
Zinc metal is losing electrons and is oxidized
to zinc ion.
 Oxidation State: is changed from 0 → +2
Hence Zn is reducing agent.

9. SOME COMMON REDUCING
REAGENTS
 Sodium amalgam (Na(Hg))
 Zinc amalgam(Zn(Hg)) used in Clemmensen
reduction.
 Sulfite compounds
 Sodium lead alloy (Na+Pb)
 Hydrazine used in Wolff-kishner reduction.
 Dithiothreitol (DTT) used to avoid S-S bonds.
 Cyanides
 TCEP

10. HOW TO IDENTIFY REDUCING
AGENTS?
 Simply look at the oxidation number
before and after the reaction.
 If the oxidation number is less in product
than the reactant, than it has gained
electrons and is reduced.
Na¹⁺ + e⁻→ Na
reduction

11. REDUCING REAGENTS IN
PERIODIC TABLE
 Oxidizing reagents are electron donors.
Elements which readily donate electrons
to achieve a full shell and become
positive ions.
 Such elements comprise those on the
extreme left of the periodic table.
Elements of group I and II will be
reducing agents.
 Such as Na, K, Rb, Ca, Mg, Ba are
reducing agents.

12. ELECTRON DONORS
 Electron donors participate in electron
transfer reactions. So in this sense
reducing reagents are also known as
electron donors.
 A well known reducing agent is
ferrocyanide [Fe(CN)₆]⁴⁻. It oxidizes or
donates an electron to form
ferricyanide[Fe(CN)₆]ᶟ⁻.

13. ATOM TRANSFER REAGENTS
 In common usage reducing reagents transfer
hydrogen atoms to a substrate. So in this relation
they can be termed as hydrogenation reagents or
hydrogen atom transfers.
 EXAMPLES:
LiAlH₄
Lindlar catalyst
NaBH₄
DIBAL-H
Formic acid (HCOOH)
Ascorbic acid(C₆H₈O₆)

14. APPLICATIONS OF REDUCING
REAGENTS
 IN INDUSTRIES:
 The principle industrial reducing agents
are carbon and hydrogen.
Hydrogen is used in smaller scale
metallurgical processes and in cases
where a metal might react with carbon.
E.g tungsten metal is produced by
passing a stream of H₂ over the oxide of
tungsten at 1200°C.

15.  EXTRACTION OF METALS:
 Carbon is used extensively in large scale
metallurgical operations.
 By using a suitable reducing agent, metal
oxides can be reduced to metals. E.g Fe₂O₃ is
reduced to iron in the blast furnace using
coke as reducing agent.
Fe₂O₃ + 3C → 2Fe + 3CO
Iron oxide Iron
Here happens the removal of
oxygen(reduction).

16. IN ORGANIC CHEMISTRY
 Here reduction basically refers to addition
of hydrogen to a molecule.
For example benzene is reduced to
cyclohexane in the presence of platinum
catalyst.
C₆H₆ + 3H₂→ C₆H₁₂
 In organic chemistry Good reducing
agents are those which deliver H₂.

17. IN ANALYTICAL CHEMISTRY
 Percentage of iron in iron ore is
determined practically by titrating the ore
with KMnO₄ solution. Here iron of the
ore acts as reducing agent.
5Fe²⁺+MnO₄¹⁻+8H₂SO₄→5Feᶟ⁺+Mn²⁺+4H₂O
 Reducing agents are used for air pollution
studies.

18. IN PHOTOSYNTHESIS
 In this process Green plants convert CO₂
And H₂O to carbohydrates in presence of
sunlight. It is sensitized by chlorophyll.
 During this reaction CO₂ is reduced to
carbohydrates.

19. SOME OTHER APPLICATIONS
 Chromium production
 Electrochemical analysis
 Ferromolybdenum production
 Magnesium production
 In production of rare earth elements.