CHEMICAL REACTION AND EQUATION CLASS 10 NOTES

* CHEMICAL:- The process in which new substance with new property are formed

eg:- 1 burning of magnesium ribbon.

2 burning of paper. 

3 digestive of food.

* REACTANTS:- The substance which take part in chemical reaction are called reactant.

* PRODUCT:- The substances which are formed in chemical reaction are called product.

eg:- MG + O2 > MGO

* BALANCED CHEMICAL EQUATION:- The balance chemical equation has an equal number of atoms of different elements in "reactant and product"

eg:- ZN + H2SO4 > ZNSO4 + H2

  => TYPE OF CHEMICAL REACTION 

 * UNBALANCED CHEMICAL EQUATION:- An unbalanced chemical equation has an equal number of atoms of different elements in reactant and product.

eg:- H2 + O2 > H2O

* COMBINATION REACTION:- The  reaction in which two or more reactant are combined to form a single product.

eg:- BURNING OF COAL

        C + O2 > CO2

* Decomposition reaction : Reactions in which one compound decomposes in two or more compounds or elements are known as Decomposition Reaction. A decomposition reaction is just the opposite of combination reaction.

A general decomposition reaction can be represented as follows :

AB → A + B

Examples:

When calcium carbonate is heated, it decomposes into calcium oxide and carbon dioxide.

CaCO3(s) \underrightarrow { heat } CaO(s) + CO2(g)

Calcium carbonate → Calcium oxide + Carbon dioxide

* THERMAL DECOMPOSITION : The decomposition of a substance on heating is known as Thermal Decomposition.

Example: 2Pb(NO3)2(s) \underrightarrow { heat } 2PbO(s) + 4NO2(g) + O2(g

* ELECTROLYTIC DECOMPOSITION : Reactions in which compounds decompose into simpler compounds because of passing of electricity, are known as Electrolytic Decomposition. This is also known as Electrolysis.

Example: When electricity is passed in water, it decomposes into hydrogen and oxygen.

2H2O(l) \xrightarrow [ Electrolysis ]{ Electric\quad Current } 2H2(g) + O2(g)

Photolysis or Photo Decomposition Reaction: Reactions in which a compound decomposes because of sunlight are known as Photolysis or Photo Decomposition Reaction.

Example: When silver chloride is put in sunlight, it decomposes into silver metal and chlorine gas.

2AgCl(s) (white) \underrightarrow { Sunlight } 2Ag(s) (grey) + Cl2(g)

Displacement Reaction: The chemical reactions in which a more reactive element displaces a less reactive element from a compound is known as Displacement Reactions. Displacement reactions are also known as Substitution Reaction or Single Displacement/ replacement reactions.

A general displacement reaction can be represented by using a chemical equation as follows :

A + BC → AC + B

Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)

* DOUBLE DISPLACEMENT REACTION : Reactions in which ions are exchanged between two reactants forming new compounds are called Double Displacement Reactions.

AB + CD → AC + BD

Examples:

When the solution of barium chloride reacts with the solution of sodium sulphate, white precipitate of barium sulphate is formed along with sodium chloride.

BaCl2(aq) + Na2SO4(aq) → BaSO4(s) (Precipitate) + 2NaCl(aq)

* PRECIPITATION REACTION : The reaction in which precipitate is formed by the mixing of the aqueous solution of two salts is called Precipitation Reaction.

* NEUTRALIZATION REACTION : The reaction in which an acid reacts with a base to form salt and water by an exchange of ions is called Neutralization REACTION.