As the CBSE Class 10 Science board exam is scheduled for February 25, 2026, CBSE Class 10 Science Notes Chapter 1 are given here for last-minute preparation. This chapter helps students quickly revise the core chemistry concepts in a clear, structured, and exam-oriented way.
Using Chemical Reactions and Equations Class 10 notes, students can revise types of reactions, balancing chemical equations, corrosion with easy examples and step-wise explanations.
These NCERT-based Science notes are given for revision, numerical practice, and answer-writing improvement just before the board exams.
What is Chemical Reaction and Equation?
Chemical Reaction and Equation Class 10 form the foundation of chemistry. They describe how substances transform into new ones.
These class 10 chemical reaction and equation notes simplify the concepts of chemical reactions and how to represent them using chemical equations. This chapter is important for CBSE Class 10 Science board exam.
Observations in a Chemical Reaction
During a chemical reaction or chemical change, certain noticeable changes can be observed, which indicate that a reaction has taken place.
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Formation of new substances
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Change in mass of reactants and products
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Energy changes, such as heat or light being absorbed or released
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Evolution of gas
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Change in temperature
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Permanent change in colour and/or physical state
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Formation of a precipitate
Chemical Reactions and Equations Class 10 Notes Chapter 1 NCERT
Chemical Reaction and Equation Class 10 Notes explain how chemical reactions occur and how they are represented using balanced chemical equations.
These notes cover types of reactions, corrosion, and rancidity in a simple and exam-focused manner. They are NCERT-based and help students with effective revision and better exam preparation.
Chemical Reactions
A chemical reaction is a process where one or more substances convert into different substances. Bonds break and form. This leads to new chemicals with new properties. For example, burning magnesium ribbon forms a new white powder.
Chemical Equations
Chemical equations are symbolic representations of chemical reactions. They use chemical formulas to show reactants and products. Reactants are on the left side, products on the right. An arrow indicates the direction of the reaction.
Writing Chemical Formulas
Writing correct chemical formulas is basic to equations. It relies on the valency of elements and ions. For instance, Sodium chloride is NaCl. Aluminium chloride is. Ferrous sulphate is. Lead nitrate is.
Balancing Chemical Equations
A balanced chemical equation has an equal number of atoms of each element on both sides. This respects the Law of Conservation of Mass. Mass can neither be created nor destroyed in a chemical reaction. Balancing ensures that the total mass of reactants equals the total mass of products.
Types of Chemical Reactions Class 10 Chemistry Chapter 1
Chemical reactions are categorised based on how atoms rearrange.
A. Combination Reaction
A combination reaction is a type of chemical reaction in which two or more reactants combine to form a single product.
Example 1: Burning of Magnesium Ribbon
Observation:
Magnesium ribbon burns with a bright, dazzling white flame and forms a white powder called magnesium oxide.
Example 2: Reaction of Quicklime with Water
Explanation:
Quicklime (calcium oxide) reacts vigorously with water to form slaked lime (calcium hydroxide). This reaction releases a large amount of heat, making it an exothermic combination reaction.
B. Decomposition
1. Decomposition of Ferrous Sulphate
Ferrous sulphate crystals 
are green in colour. When heated, they first lose water of crystallisation and turn white. On further heating, they decompose to form reddish-brown ferric oxide 
along with sulphur dioxide and sulphur trioxide gases.
2. Decomposition of Lead Nitrate
When lead nitrate
, a white powder, is heated, it decomposes to form yellow lead oxide 
as a residue. During this reaction, brown fumes of nitrogen dioxide 
and 
are also released
C. Displacement Reaction
A displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element from its compound.
Example: Reaction between Iron and Copper Sulphate
Observation:
When an iron nail is placed in a blue copper sulphate solution, the blue colour fades and turns pale green due to the formation of iron sulphate. At the same time, a reddish-brown deposit of copper is seen on the iron nail.
D. Double Displacement Reaction
A double displacement reaction is a chemical reaction in which ions of two reactants are exchanged, resulting in the formation of two new compounds.
Precipitation Reaction
In many double displacement reactions, one of the products formed is an insoluble solid known as a precipitate.
Example: Reaction between Sodium Sulphate and Barium Chloride
Observation:
A white precipitate of barium sulphate 
is formed, indicating a precipitation reaction.
Oxidation and Reduction Reactions (Redox)
A redox reaction is a chemical reaction in which oxidation and reduction occur simultaneously due to a change in the oxidation states of the substances involved. In any redox reaction, one substance loses electrons while another gains electrons.
Oxidation
Oxidation refers to the process in which a substance:
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Loses electrons, or
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Gains oxygen, or
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Loses hydrogen
Reduction
Reduction refers to the process in which a substance:
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Gains electrons, or
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Loses oxygen, or
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Gains hydrogen
Effects of Oxidation in Daily Life
Oxidation reactions impact our daily lives significantly.
Corrosion
When a metal reacts with substances like moisture and acid, it corrodes. This process damages the metal. Rusting of iron is a common example. Tarnishing of silver and green coating on copper are also corrosion.
Rancidity
Fats and oils in food oxidise when exposed to air. This causes an unpleasant smell and taste, known as rancidity.
Prevention: Adding antioxidants, storing food in airtight containers, flushing with nitrogen gas (e.g., in chip bags).
Physical and Chemical Changes
Physical changes alter appearance but not composition (e.g., ice melting). Chemical changes form new substances with new properties (e.g., burning paper).
Key Rules for Balancing Chemical Equations
Law of Conservation of Mass
According to the Law of Conservation of Mass, matter is neither created nor destroyed during a chemical reaction. This means that the total number of atoms of each element remains the same before and after the reaction. As a result, the total mass of the reactants is always equal to the total mass of the products formed in a chemical reaction.
Balanced Chemical Equation
A balanced chemical equation is one in which the number of atoms of each element on the reactants side is equal to the number of atoms on the products side. Balancing an equation ensures that it follows the Law of Conservation of Mass.
Balancing Chemical Equations
Chemical equations are used to represent the changes that occur during a chemical reaction.
\nReactants → Products
To maintain balance, the number of each type of atom must be equal on both sides of the equation.
Balancing is done by placing coefficients in front of chemical symbols or formulas. A coefficient is a numerical value that indicates the number of molecules or atoms participating in the reaction.
Steps for Balancing Chemical Equations
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Write the unbalanced chemical equation.
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Count the number of atoms of each element on both sides.
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Adjust the coefficients (not subscripts) to make the number of atoms equal.
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Recheck to ensure all atoms are balanced on both sides.
Example
Unbalanced equation:
Zn + HCl → ZnCl₂ + H₂
Balanced equation:
Zn + 2HCl → ZnCl₂ + H₂
Hit and Trial Method
The hit-and-trial method involves repeatedly adjusting the coefficients until the number of atoms of each element becomes equal on both sides of the chemical equation. This is the most commonly used method for balancing equations at the Class 10 level.
Reactivity Series
This series lists metals in order of decreasing reactivity. A metal higher in the series can displace a metal lower in the series from its salt solution.
Oxidation-Reduction Rules
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Substance gaining oxygen or losing hydrogen is oxidised.
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Substance losing oxygen or gaining hydrogen is reduced.
Chemical Reactions and Equations Class 10 Notes PDF Download Free
The Chemical Reactions and Equations Class 10 Notes PDF provides students a clear, concise, and exam-focused explanation of fundamental chemistry concepts as per the latest NCERT syllabus.
These notes simplify complex reactions, equations, and definitions. This makes it easier for students to revise easily before the board exam.
Chemical Reactions and Equations Class 10 Notes PDF Download
How to Use Chemical Reactions and Equations Notes for Last-Minute Board Exam Revision
With the Class 10 Science exam scheduled on February 25, 2026, this chapter becomes extremely important for quick scoring.
Start by revising all types of chemical reactions, balancing methods, and key definitions directly from the notes.
Focus on examples frequently asked in board exams, such as combination, displacement, and redox reactions.
In the final days, use these notes alongside NCERT questions, exemplar problems, and previous year questions to strengthen answer-writing skills.
Revise chemical equations daily, practice balancing at least 10–15 equations, and memorise definitions related to corrosion and rancidity.
This targeted approach will help you revise faster, avoid common mistakes, and improve marks in the Class 10 Science board examination.
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