Class 10 science lesson 1 chemical reactions and Equations notes

 1.Chemical reaction and Equation

Chemical Reactions: A chemical reaction happens when one or more chemicals are changed into one or more other chemical.

Chemical Equation:The method of representing a chemical reaction with the help of symbols and formulae of the substances involved in it, is known as Chemical Equation.

Balancing of an Equation:The process of making the number of atoms of each element equal on both the sides of an Equation is called balancing of an equation.

H2+Cl2--------2HCl

COMBINATION REACTION:A chemical reaction in which two or more substances combine to form a single substances is called a combination reaction.

C2+O2-------CO2

Decomposition Reaction:A reaction in which a substances break down into two or more substances is called decomposition reaction.

2NaCl-----------2Na+Cl2

Displacement Reaction:A chemical reaction in which a more reactive metals displaces a less reactive metal from its salt solution is called Displacement reaction.

Zn+CuSO4--------ZnSO4+Cu

Double Displacement reaction two different atoms or group of atoms are exchanged.

BaCl2+Na2SO4---------BaSo4+2NaCl

Double displacement reaction are also called precipitation reaction during which insoluble salts are produced.

During some reaction heat is given out and they are called Exothermic reaction while in some reaction heat is absorbed and they are called Endothermic Reaction.

The process of additional of oxygen or Removal of hydrogen is known as oxidation whereas Removal of oxygen or addition of hydrogen is known as Reduction.