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Chemical Reactions and Equations Class 10
Notes Science Chapter 1
January 22, 2024 by Sastry CBSE



CBSE Class 10 Science Notes Chapter 1 Chemical Reactions and Equations Pdf free download is part of
Class 10 Science Notes for Quick Revision. Here we have given NCERT Class 10 Science Notes Chapter 1
Chemical Reactions and Equations.


According to new CBSE Exam Pattern, MCQ Questions for Class 10 Science pdf Carries 20 Marks.


CBSE Class 10 Science Notes Chapter 1 Chemical
Reactions and Equations
Chemical Reactions and Equations: Balanced and unbalanced chemical equations and balancing of
chemical equations.


What is a chemical reaction Class 10?
Chemical Reaction: The transformation of chemical substance into another chemical substance is known
as Chemical Reaction. For example: Rusting of iron, the setting of milk into curd, digestion of food,
respiration, etc.


In a chemical reaction, a new substance is formed which is completely different in properties from the
original substance, so in a chemical reaction, a chemical change takes place.
Only a rearrangement of atoms takes place in a chemical reaction.


The substances which take part in a chemical reaction are called reactants.

, The new substances produced as a result of a chemical reaction are called products.
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Example: The burning of magnesium in the air to form magnesium oxide is an example of a chemical
reaction.
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2Mg(s) + O2(g) △ 2MgO(s)
→
Before burning in air, the magnesium ribbon is cleaned by rubbing with sandpaper.
This is done to remove the protective layer of basic magnesium carbonate from the surface of the
magnesium ribbon.


Reactant: Substances which take part in a chemical reaction are called reactants.
Example: Mg and O2.


Product: New substance formed after a chemical reaction is called a product.
Example: MgO.


Characteristics of Chemical Reactions :
(i) Evolution of gas: The chemical reaction between zinc and dilute sulphuric acid is characterised by the
evolution of hydrogen gas.
Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g) ↑


(ii) Change in Colour: The chemical reaction between citric acid and purple coloured potassium
permanganate solution is characterised by a change in colour from purple to colourless.
The chemical reaction between sulphur dioxide gas and acidified potassium dichromate solution is
characterized by a change in colour from orange to green.


(iii) Change in state of substance: The combustion reaction of candle wax is characterised by a change in
state from solid to liquid and gas (because the wax is a solid, water formed by the combustion of wax is a
liquid at room temperature whereas, carbon dioxide produced by the combustion of wax is a gas). There are
some chemical reactions which can show more than one characteristics.


(iv) Change in temperature: The chemical reaction between quick lime water to form slaked lime is
characterized by a change in temperature (which is a rise in temperature).
The chemical reaction between zinc granules and dilute sulphuric acid is also characterised by a change in
temperature (which is a rise in temperature).


(v) Formation of precipitate: The chemical reaction between sulphuric acid and barium chloride solution is
characterised by the formation of a white precipitate of barium sulphate.
BaCl2(aq) + H2SO4(aq) → BaSO4(s) (ppt) + 2HCl(aq)


What is a chemical Equation Class 10?