CHEMISTRY
CHAPTER NO.1: CHEMICAL REACTIONS AND EQUATION
•Chemical reactions:
It is a process in which new substance with new properties are formed.
It is also known taken as the shorthand representation of Chemical change.
It involves the breaking of old bonds and the making of new bonds.
It involves 3 main steps:
1. Absorption of energy and breaking of old bonds.
2. Rearrangement of atoms.
3. Formation of new bonds.
In a chemical reaction, the electrons in the outermost shell of atom participate and the remaining part
of atoms including nucleus remains undisturbed.eg
● Photosynthesis
● Cellular respiration
● Corrosion of metals
● Rusting of iron
● Combustion
•Charecterstics of a chemical reaction:
The easily available observable features of chemical reaction are:
1. CHANGE IN STATE: A chemical reaction sometimes changes the state of a substance
Eg. Electrolysis of water-liquid changes to gas.
2. CHANGE IN COLOUR: A chemical reaction sometimes changes the colour of a substance.
Eg. Rusting of iron
3. CHANGE IN TEMPERATURE: A chemical reaction may cause temperature change.
Eg. Calcium oxide + water=Heat + slaked lime
4. FORMATION OF PRECIPITATE: A
chemical change might cause formation of precipitate.
Eg. Barium chloride+sulfuric acid
Leads to the formation of white precipitate barium sulphate.
5. EVOLUTION OF GAS: A chemical change may cause evolution of gas.
Eg. Zinc + sulphuric acid leadd to formation of zinc sulphate and hydrogen gas.
•Types of chemical reaction on basis of temperature change:
There are 2 types of chemical reaction based on temperature change.
CHAPTER NO.1: CHEMICAL REACTIONS AND EQUATION
•Chemical reactions:
It is a process in which new substance with new properties are formed.
It is also known taken as the shorthand representation of Chemical change.
It involves the breaking of old bonds and the making of new bonds.
It involves 3 main steps:
1. Absorption of energy and breaking of old bonds.
2. Rearrangement of atoms.
3. Formation of new bonds.
In a chemical reaction, the electrons in the outermost shell of atom participate and the remaining part
of atoms including nucleus remains undisturbed.eg
● Photosynthesis
● Cellular respiration
● Corrosion of metals
● Rusting of iron
● Combustion
•Charecterstics of a chemical reaction:
The easily available observable features of chemical reaction are:
1. CHANGE IN STATE: A chemical reaction sometimes changes the state of a substance
Eg. Electrolysis of water-liquid changes to gas.
2. CHANGE IN COLOUR: A chemical reaction sometimes changes the colour of a substance.
Eg. Rusting of iron
3. CHANGE IN TEMPERATURE: A chemical reaction may cause temperature change.
Eg. Calcium oxide + water=Heat + slaked lime
4. FORMATION OF PRECIPITATE: A
chemical change might cause formation of precipitate.
Eg. Barium chloride+sulfuric acid
Leads to the formation of white precipitate barium sulphate.
5. EVOLUTION OF GAS: A chemical change may cause evolution of gas.
Eg. Zinc + sulphuric acid leadd to formation of zinc sulphate and hydrogen gas.
•Types of chemical reaction on basis of temperature change:
There are 2 types of chemical reaction based on temperature change.
