1.Chemical Equations
Chemical change – one or more new substances with new physical and chemical properties are formed.

Here, when copper sulphate reacts with iron, two new substances, i.e., ferrous sulphate and copper are formed.
1.Chemical Equations
A chemical equation is a statement or representation that describes a chemical reaction in terms of
symbol and formulae.
➢ A chemical reaction is the transformation of chemical substance called reactants into another chemical
substance called products. In a chemical reaction, only rearrangement of atoms takes place.
➢ The substances which take part in a chemical reaction are called reactants. The reactants are written
on the left hand side. The new substances produced as a result of chemical reaction are called
products. The products are written on the right hand side.
Some of the symbols used in a chemical Equation are :
(a) Solids (s)
(b) Liquids (l)
(c) Gases (g)
(d) Aqueous solutions (aq)
(e) Gas released as a product (↑)
(f) Precipitate formed in the reaction (↓)
(g) Direction of reaction (→)
➢ Steps to balance a chemical equation :
(a) Write word equation.
(b) Then write skeletal chemical equation.
(c) Enclose the formula in the boxes.
(d) List the number of atoms of different elements present in the unbalanced equation.
(e) Start balancing with the compound that contains the maximum number of atoms.
(f) Start balancing other atoms.
(g) Check the correctness of the balanced equation.
1.Chemical Equations
- Books Name
- SonikaAnandAcademy Science Book
- Publication
- SonikaAnandAcademy
- Course
- CBSE Class 10
- Subject
- Science
NCERT Solutions -Class 10 -Chemical Reactions and Equations
Chemical Reaction
When two or more substance react with each other to form one or more new substance this is called chemical reaction
The substances which reacts with each other in a chemical reaction are known as reactants they are generally written on the left hand side of the equation
The substances which are formed in a chemical reaction are known as product they are generally written on the right hand side of the equation
Chemical reactions can be of different types
1) Combination reaction-- when two or more substances combine together to form a new substance is called combination reaction
Symbolically
A+B ------C
Two substances A and B are combined together to form a new substance C
Example
H2+Cl2------2HCl
2) Decomposition reaction-- when a substance decomposes into two or more substances is called decomposition reaction
Symbolically
C---A+B
The compound C decomposes to two compounds A and. B
Example
ZnCO3------Zn + CO2
The composition of a compound can be done by either of the methods
--- by thermal decomposition
--- by electrolysis
-----by photolysis reaction
3) Displacement Reaction
When an element of a compound displaces by another element during a chemical reaction is known as displacement reaction
Symbolically
AB+C-----AC+B
In above equation element C displaces element B of the compound AB so this type of reaction is known as displacement reaction
2HCl+Mg------MgCl2 + H2
4) Double displacement reaction
When elements of compounds and exchanged each other in a chemical reaction what is known as double displacement reaction
Symbolically
AB+CD-----AD+BC
In the above reaction elements of the compound AB and elements of the compounds CD are exchange together to form a compounds AD and BC
2KBr+BaI2-------2KI. + BaBr2
Types of reactions positive ion of one compound reacts with negative ions of another compound similarly in negative ions of the first compound combines with positive
Redox Reaction
The reaction in which there is a oxidation and reduction both occurs is known as red oxide reaction in this type of reaction there is gain of electron in one element and loss of electrons in an atom
The element which gains electrons undergoes oxidation reaction it can also be defined as addition of oxygen is known as oxidation reaction
The element which loses electron undergoes reduction reaction or in other words addition of hydrogen is known as reduction reaction
The substance which undergoes oxidation is known as reducing agent
The substance which undergoes reduction is known as oxidising agent
Limiting Reagent
The substance which consumes completely in a chemical reaction is called limiting reagent generali on limiting reagent decide the extent of a chemical reaction
2.Types of Chemical Reactions
Notes by teacher
3.Effects of Oxidation Reactions in Everyday Life
note by teacher
Sagar Daksh Science Book > Unit I: Chemical Substances - Nature and Behaviour > Chapter 1 Chemical reactions > Implications of a balanced chemical equation.
Types of chemical reactions: combination, decomposition, displacement, double displacement, precipitation, neutralization, oxidation and reduction.
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