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Tejendra BIOCHEM.pptx
1. Guided By :-
Dr. Jipsi Chandra Mam
Presented By :-
Tejendra Baghel
{3rd Semester}
2.
3. Redox reactions are oxidation-reduction chemical reactions in
which the reactants undergo a change in their oxidation states.
The term ‘redox’ is a short form of reduction-oxidation.
All the redox reactions can be broken down into two different
processes – a reduction process and an oxidation process.
4. Addition of oxygen/electronegative element to a substance.
Removal of hydrogen/electropositive element from a substance.
Loss of electron(s) by any species.
An increase in the oxidation number of the element in the given
substance.
Examples:-
S(s) + O2 (g) → SO2 (g)
CH4(g) + 2O2(g) → CO2(g) + 2H2O (l)
5. Removal of oxygen/electronegative element from a substance.
Addition of hydrogen/electropositive element to a substance.
Gain of electron(s) by any species.
A decrease in the oxidation number of the element in the
given substance.
Examples:-
2CH2CH2(g) + H2(g) → 2CH3CH3(g)
2FeCl3(aq) + H2(g) → 2FeCl2(aq) + 2HCl (aq)
6. Oxidation number is defined as the charge or the apparent charge that an atom
in a compound or ion would have, if all of the electrons in its bonds belonged
entirely to the more electronegative atom.
Rules for assigning oxidation numbers:-
1. An atom in its elemental state, 0.
2. An atom in a simple monoatomic ion, charge on the ion.
3. The sum of all the oxidation numbers in a molecule or a polyatomic ion,
charge on the particle.
4. Oxidation number of oxygen is –2. There are three exceptions here.
A. Peroxides :- [ –1] Example:- Na2O2
B. Superoxides :- [–(1/2)] Example:- KO2
C. Oxygen is bonded to fluorine :- [+1]Example:- F2O2
5. Oxidation number of Hydrogen is +1, excluding when it is bonded to
metals containing two elements. Example, CaH2, oxidation number ,[–1].
6. Fluorine and other halogens have an oxidation number –1 when they
appear as halide ions in their compounds. When iodine, chlorine, and
bromine are combined with oxygen, their oxidation number is positive.
7. Acceptor of electron(s)
Reagent which can increase the oxidation number of an element
in a given substance.
These reagents are called as oxidants also.
Important Oxidizing Agents
A. Molecules are made up of electronegative elements.
Eg: O2 , O3 , and X2 (halogens)
B. Compounds containing an element that is in the higher
oxidized state. Eg: KMnO4 , K2Cr2O7 , HNO3 , KCl3.
C. Oxides of metals and non-metals .
Eg: MgO, CuO, CrO3, P4O10
D. Fluorine is the strongest oxidizing agent.
8. Donor of electron(s).
A reagent which lowers the oxidation number of an element in a
given substance.
These reagents are also called as reductants.
Important Reducing Agents
A. All metals, for example Na, Zn, Fe, Al.
B. A few non-metals such as C, H , S, P .
C. Hydracids, for example HCl, HBr, HI, H2S.
D. Few compounds contain an element in the lower oxidation state.
Examples include: FeCl2, FeSO4 , SnCl2 , Hg2Cl2 .
E. Metallic hydrides including NaH, LiH, CaH2 , etc.
F. Organic compounds like HCOOH .
G. Lithium is the strongest reducing agent in the solution.
H. Cesium is the strongest reducing agent in the absence of water.
I. The substances which act as oxidizing as well as reducing agents are
H2O2 , SO2 , H2SO3 , HNO2, NaNO2 .
9. Decomposition Reaction
Reaction which involves the breakdown of a compound into different
compounds. Examples of these types of reactions are:
2NaH → 2Na + H2
2H2O → H2 + O2
Na2CO3 → Na2O + CO2
All the above reactions result in the breakdown of smaller chemical
compounds in the form of AB → A + B
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Combination Reaction
These reactions are the opposite of decomposition reactions.
These involve the combination of two compounds to form a single
compound in the form of A + B → AB. For example:
H2 + Cl2 → 2HCl
C + O2 → CO2
4Fe+ 3O2 → 2Fe2O3
10. Displacement Reaction
In this kind of reaction, an atom or an ion in a compound is
replaced by an atom or an ion of another element.
It can be represented in the form of X + YZ → XZ + Y.
1) Metal Displacement
In this type of reaction, a metal present in the compound is displaced by
another metal.
These types of reactions find their application in metallurgical processes
where pure metals are obtained from their ores.
For Example:- CuSO4 + Zn → Cu + ZnSO4
2) Non-Metal Displacement
In this type of reaction, we can find a hydrogen displacement and
sometimes rarely occurring reactions involving oxygen displacement.
For Example:- Ca(s) + 2H2O(l) → Ca(OH)2 (aq) + H2(g)
12. Applications of Redox Reaction in Electrochemistry
The battery used for generating DC current uses a redox
reaction to produce electrical energy.
In Daniel Cell:-
Zn(s) + Cu2++(aq) → Zn2++(aq) + Cu(s)
Reactions at the two electrodes are:-
At anode: Zn (s) ⟶ Zn2+(aq) + 2e–
At cathode: Cu2+(aq) + 2e– ⟶ Cu (s)
Batteries or electrochemical cells used in our day-to-day life are
also based on redox reactions.
13. Redox Reactions in Biology
Cellular Respiration :-
C6H12O 6 [Glucose]+ 6 O2 → 6 CO2 + 6 H2O
Oxidation:-
Glucose(C6H12O6) into CO2
Reduction:-
Oxygen (O2) to H2O.
14. Photosynthesis :-
6 CO2 + 6 H2O + light energy → C6H12O6[Glucose] + 6O2
Reduction
CO2 into Sugar
Oxidation
H2O into O2
15. Real-Life Uses of Redox Reaction :-
Production of some important chemicals is also based on electrolysis
which in turn is based on redox reactions. Many chemicals like caustic
soda, chlorine, etc., are produced using redox reactions.
Oxidation-Reduction reactions also find their application in sanitizing
water and bleaching materials.
The surfaces of many metals can be protected from corrosion by
connecting them to sacrificial anodes, which undergo corrosion instead. A
common example of this technique is the galvanization of steel.
The industrial production of cleaning products involves the oxidation
process.
16. Nitric acid, a component of many fertilizers, is produced from the oxidation
reaction of ammonia.
Electroplating is a process that uses redox reactions to apply a thin coating of a
material on an object. Electroplating is used in the production of gold-plated jewellery.
Many metals are separated from their ores with the help of redox reactions. One
such example is the smelting of metal sulfides in the presence of reducing agents.
The main source of oxidation is oxygen, and therefore redox reactions or oxidation-
reduction reactions are responsible for food spoilage.
17.
18. Word origin: Greek. hydor = water + lyein = to loosen, dissolve.
The process of splitting a compound into fragments with the addition
of water; a kind of reaction that is used to break down polymers into
simpler units, e.g. starch into glucose.
Hydrolysis is a chemical reaction of the interaction of chemicals with
water, leading to the decomposition of both the substance and water.
The hydrolysis reaction may be represented by the reversible chemical
equation :- AB + HOH ⇌ AH + BOH
19. Reactions of hydrolysis are possible with salts, carbohydrates,
proteins, fats, etc.
Hydrolysis of organic substances in catabolism reactions
occurs, as a rule, with the participation of enzymes.
Proteins are split into amino acids, fats into glycerol and fatty
acids, and polysaccharides into monosaccharides.
The following is the example of the hydrolysis reaction of
carbohydrates :- (С6Н10О5)n + nН2О ↔ nC6H12O6
20. Hydrolysis Of Salts:-
Most common type of hydrolysis.
Hydrolysis of salts generally refers to the reaction of salt with
water where it involves the interaction between cations or anions of
salts and water.
During hydrolysis, a salt breaks down to form ions, completely
or partially depending upon the solubility factor.
21. Hydrolysis Of Acid and Base:-
Acid–base-catalysed hydrolysis can be found during the
hydrolysis of esters or amides.
Here, the process of hydrolysis occurs when water or hydroxyl
ion reacts with the carbon of the carbonyl group of the ester or amide
where new compounds are formed.
The products of both hydrolysis are compounds with carboxylic
acid groups.
22. Hydrolysis Of ATP:-
Most biochemical reactions that occur in living organisms are
in the form of ATP hydrolysis which takes place with the help of
enzymes acting as catalysts.
The catalytic action of enzymes allows the hydrolysis or
breaking down of proteins, lipids, oils, fats and carbohydrates.
