Redox reaction notes
Redox Reaction :-
Chemical reaction which involve both oxidation and reduction process simultaneously, are known as redox reaction.
Oxidation :-
1. It involves addition of oxygen to an element or compound, or the removal of hydrogen from compound.
2. Addition of electronegative element or removal of any other electropositive element.
3. Oxidation is the loss of electrons in an atom, Ion or molecule is also known as the de-electronation.
4. Oxidation involves increase in oxidation number.
5. Oxidation is caused by oxidizing agent.
Reduction :-
1. It involves addition of the hydrogen to an element or compound, or the removal of oxygen from the compound.
2. Addition of electropositive element or removal of any other electronegative element.
3. Reduction is the gain of electrons in an atom, Ions or molecule this process is known as electronation.
4. Reduction involves decrease in oxidation number.
5. Reduction is caused by reducing agent.
Oxidation Number :-
Oxidation number is defined as the charge in which an atom appears to have when all other atom are removed from its as ions.
It may be + or - sign.
An element may have different values of oxidation number depending upon the nature of compound in which it is present.
Important Points for Determining Oxidation Number.
1. Algebraic sum of oxidation number of all the atom in uncharge (neutral) compound is zero. In an iron the algebraic sum is equal to the charge on the ion.
2. All elements in the elementary state have oxidation number zero.
E.g. - He, H, etc
3. Oxidation number for alkali metal is + 1 and for alkaline earth metal is + two.
4. Oxidation number of metal in amalgams is zero.
5. Is fluorine is the most electronegative element is always have an oxidation number of -1 in all of its compound.
Types of Redox Reaction
1. Intermolecular Redox Reaction
In such reactions, oxidation and reduction takes place separately in twocompounds.
2. Intarmolecular Redox Reaction
In these reaction, oxidation and reduction takes place in the single compound.
3. Disproportionation reaction
This reaction involved reduction and oxidation of same element of compound.
Balancing of Redox Chemical Equation
Every chemical equation must be balanced according to the law of conservation of mass.in a balanced chemical equation the atom of the various species involved in the reactant and product must be equal in number. Redox reaction can be balance through Ion electron method and oxidation number method.
Ion Electron Method (Half Reaction Method)
This method of balancing was developed by Jette and Lamer in 1927.
It was the following step.
Step 1 :- Write the Redox reaction in ionic form.
Step 2 :- Split the Redox reaction into its oxidation-half and reduction half-reaction.
Step 3 :- Balance atom of each half reaction except hydrogen and oxygen by using simple multiplies.
Step 4 :- Balance hydrogen and oxygen as
1. For acidic and neutral solution - add H2O molecule to the side deficient in oxygen and H plus to the side deficient in hydrogen.
2. For Alkaline Solution :- for is excess of oxygen, add one water molecule of the same side and OH- Ion two other side to balance hydrogen.
Step 5 :- Add electron to the site deficient in electron.
Step 6 :- Equalising the number of electron in the both reaction by multiplying a suitable number.
Step 7 :- Add the to balance half equation and cancel common term of opposite side.
Step 8 :- Convert the ionic reaction intermolecular form adding spectator ions.
Oxidation Number Method
It involves the following step
Step 1 :- Write the skeleton equation (if not given)
Step 2 :- Assign oxidation number of each atom.
Step 3 :- Balance atom other than Hydrogen and Oxygen into process
Step 4 :- Equalise the total increase or decrease in oxidation number.
Step 5 :- Balance Hydrogen and Oxygen.
Redox Reaction in Daily Life
Oxidation process Reduction process
It involves in It involves in
Corrosion. Photography
Bleaching Antioxidants
Antiseptics Photosynthesis
Combustion of fuel Metallurgy
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