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NCERT Solutions for Class 10 Chemistry Chapter 1 : Chemical Reactions and Equations

Class 10 Science Chapter 1 Chemical Reactions and Equations deals with the foundation of Chemistry. Students preparing for science class 10 chapter 1 will get to learn from the basics of chemical reactions and equations right up to the complex situations of writing an equation and balancing it. It covers all major concepts in detail, allowing students to understand the ideas better. NCERT Solutions for Class 10 Science Chapter 1 of the section, concentrates on the concept of chemical equations. Here it teaches how to represent chemical reactions in word equation form. It also deals with writing a balanced chemical equation, which is thoroughly discussed in a step-by-step way. Students will also learn about the numerous sorts of chemical reactions, with specific examples. In this chapter, students will also discover the fundamentals of chemical reactions, their types, and the implications of a chemical oxidation reaction in their daily lives.

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Chemical Reactions and Equations NCERT page wise questions and answers

Chemical Reactions and Equations practice questions

Chemical Reactions and Equations posts

Chemical Reactions and Equations brief

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Characteristics of a Chemical Reaction

Introduction to Chemical Equations

Balancing Chemical Equation - I

Balancing Chemical Equation - II

Energy Change In A Chemical Reaction (Heat)

Access NCERT Solutions for Class 10 Chemistry Chapter 1 : Chemical Reactions and Equations

In Text Page 6

Question 3

Write a balanced chemical equation with state symbols for the following reactions.
Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.

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Solution

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The balanced chemical equation is:

B a C l_{2} (a q) + N a_{2} S O_{4} (a q) \to B a S O_{4} (s) + 2 N a C l (a q)

Question 4

What is a balanced chemical equation? Why should chemical equations be balanced?

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Question 5

Translate the following statements into chemical equations and then balance them:

(a) Hydrogen gas combines with nitrogen to form ammonia.
(b) Hydrogen sulphide gas burns in air to give water and sulphur dioxide.
(c) Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.
(d) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.

Hard

Solution

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(a) Hydrogen gas combines with nitrogen to form ammonia.

H_{2} (g) + N_{2} (g) \to N H_{3}

The balanced equation for this reaction can be written as:

3 H_{2} (g) + N_{2} (g) \to 2 N H_{3}

(b) Hydrogen sulphide gas burns in air to give water and sulphur dioxide.

H_{2} S (g) + O_{2} (g) \to H_{2} O + S O_{2}

The balanced equation for this reaction can be written as:

2 H_{2} S (g) + 3 O_{2} (g) \to 2 H_{2} O + 2 S O_{2}

(c) Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.

B a C l_{2} + A l_{2} (S O_{4})_{3} \to A l C l_{3} + B a S O_{4} ↓

The balanced equation for this reaction can be written as:

3 B a C l_{2} + A l_{2} (S O_{4})_{3} \to 2 A l C l_{3} + 3 B a S O_{4} ↓

(d) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.

K + H_{2} O \to K O H + H_{2}

The balanced equation for this reaction can be written as:

2 K + 2 H_{2} O \to 2 K O H + H_{2}

Question 6

Balance the following chemical equations:

H N O_{3} + C a (O H)_{2} \to C a (N O_{3})_{2} + H_{2} O

N a O H + H_{2} S O_{4} \to N a_{2} S O_{4} + H_{2} O

N a C l + A g N O_{3} \to A g C l + N a N O_{3}

B a C l_{2} + H_{2} S O_{4} \to B a S O_{4} + H C l

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(a)

2 H N O_{3} + C a (O H)_{2} \to C a (N O_{3})_{2} + 2 H_{2} O

∙

It is a double displacement reaction since both molecules of the reactions are displaced to form new products.

∙

Nitric acid

(H N O_{3})

combines with calcium hydroxide

[C a (O H)_{2}]

to produce calcium nitrate

[C a (N O_{3})_{2}]

-a salt and water, which is a neutralization reaction.

∙

Hence, this reaction is both a double displacement as well as a neutralization reaction.

(b)

2 N a O H + H_{2} S O_{4} \to N a_{2} S O_{4} + 2 H_{2} O

∙

It is a double displacement reaction since both molecules of the reactions are displaced to form new products.

∙

Sulphuric acid

(H_{2} S O_{4})

combines with sodium hydroxide

(N a O H)

to produce sodium sulphate

(N a_{2} S O_{4})

-a salt and water, which is a neutralization reaction.

∙

Hence, this reaction is both a displacement as well as a neutralization reaction.

(c)

N a C l + A g N O_{3} \to A g C l + N a N O_{3}

∙

This is a double displacement reaction since there is an exchange of ions between the reactants, forming new products.

(d)

B a C l_{2} + H_{2} S O_{4} \to B a S O_{4} + 2 H C l

∙

This is a double displacement reaction since there is an exchange of ions between the reactants, forming new products.

Question 7

Write the balanced chemical equations for the following reactions.

(a) Calcium hydroxide + Carbon dioxide

\to

Calcium carbonate + Water

(b) Zinc + Silver nitrate

\to

Zinc nitrate + Silver

(c) Aluminium + Copper chloride

\to

Aluminium chloride + Copper

(d) Barium chloride + Potassium sulphate

\to

Barium sulphate + Potassium chloride

Hard

Solution

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(a) Calcium hydroxide + Carbon dioxide

\to

Calcium carbonate + Water

C a (O H)_{2} + C O_{2} \to C a C O_{3} + H_{2} O

(b) Zinc + Silver nitrate

\to

Zinc nitrate + Silver

Z n + 2 A g N O_{3} \to Z n (N O_{3})_{2} + 2 A g

(c) Aluminium + Copper chloride

\to

Aluminium chloride + Copper

2 A l + 3 C u C l_{2} \to 2 A l C l_{3} + 3 C u

(d) Barium chloride + Potassium sulphate

\to

Barium sulphate + Potassium chloride

B a C l_{2} + K_{2} S O_{4} \to B a S O_{4} + 2 K C l

Question 8

Write the balanced chemical equation for the following and identify the type of reaction in each case:

(a) Potassium bromide(aq) + Barium iodide(aq)

\to

Potassium iodide(aq) + Barium bromide(s)

(b) Zinc carbonate(s)

\to

Zinc oxide(s) + Carbon dioxide(g)

(c) Hydrogen(g) + Chlorine(g)

\to

Hydrogen chloride(g)

(d) Magnesium(s) + Hydrochloric acid(aq)

\to

Magnesium chloride(aq) + Hydrogen(g)

Hard

Solution

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(a) Potassium bromide(aq) + Barium iodide(aq)

\to

Potassium iodide(aq) + Barium bromide(s)

2 K B r_{(a q)} + B a I_{2}_{(a q)} \to 2 K I_{(a q)} + B a B r_{2}_{(s)}

In this reaction, both the reactants exchange ions to form two new products. Hence, it is a double displacement reaction

(b) Zinc carbonate(s)

\to

Zinc oxide(s) + Carbon dioxide(g)

Z n C O_{3}_{(s)} \to Z n O_{(s)} + C O_{2}_{(g)}

In this reaction, a single substance yields two different products. Hence, it is a decomposition reaction.

(c) Hydrogen(g) + Chlorine(g)

\to

Hydrogen chloride(g)

H_{2}_{(g)} + C l_{2}_{(g)} \to 2 H C l_{(g)}

In this reaction, two different reactants react with each other to form a single product. Hence, it is called a combination reaction.

(d) Magnesium(s) + Hydrochloric acid(aq)

\to

Magnesium chloride(aq) + Hydrogen(g)

M g_{(s)} + 2 H C l_{(a q)} \to M g C l_{2}_{(a q)} + H_{2}_{(g)}

In this reaction, more reactive Mg is replacing less reactive H. Hence, it is displacement reaction.

Question 9

What does one mean by exothermic and endothermic reactions? Give examples.

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The chemical reactions release energy in the form of heat, light, or sound, are called exothermic reactions. An exothermic reaction occurs when the temperature of a system increases due to the evolution of heat. This heat is released into the surroundings, resulting in an overall negative quantity for the heat of reaction.

An example of an exothermic reaction is the mixture of sodium and chlorine to yield table salt. This reaction produces

411 k J

of energy for each mole of salt that is produced:

2 N a (s) + C l_{2} (s) \to 2 N a C l (s) + e n e r g y

The chemical reactions that must absorb energy in order to proceed are known as endothermic reactions. An endothermic reaction occurs when the temperature of an isolated system decreases while the surroundings of a non-isolated system gain heat. Endothermic reactions result in an overall positive heat of reaction.

Photosynthesis is an example of an endothermic chemical reaction. In this process, plants use the energy from the sun to convert carbon dioxide and water into glucose and oxygen.

Question 10

Why is respiration considered an exothermic reaction? Explain.

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Hint: A reaction in which heat is released is known as an exothermic reaction.

Explanation:

Respiration is a very special form of burning fuel.
It involves the breakdown of sugar with oxygen within the cells of every living organism.
When we inhale $O_{2}$ , glucose in our cells react with $O_{2}$ and forms $C O_{2}$ and $H_{2} O$ with release of heat energy.
$C O_{2}$ produced in the reaction is thrown out from the body as we exhale.
As energy in the form of heat is produced in this reaction that is why respiration is considered as an exothermic reaction.
The reaction is as shown below;

Question 13

What is the difference between displacement and double displacement reactions? Write equations for these reactions?

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A single displacement reaction is a chemical reaction in which one element is substituted for another element in a compound, generating a new product.

For example,

2 H C l (a q) + Z n (s) \to Z n C l_{2} (a q) + H_{2} (g)

is an example of a single-displacement reaction. The hydrogen atom in

H C l

is replaced by

Z n

atoms, and in the process hydrogen gas is formed.

A double-displacement reaction occurs when parts of two ionic compounds are exchanged, making two new compounds. A characteristic of a double-displacement equation is that there are two compounds as reactants and two different compounds as products.

An example is

C u C l_{2} (a q) + 2 A g N O_{3} (a q) \to C u (N O_{3})_{2} (a q) + 2 A g C l (s)

Question 15

What do you mean by a precipitation reaction? Explain by giving examples.

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Explanation:

Precipitation reactions occur when cations and anions in aqueous solution combine to form an insoluble ionic solid called a precipitate. A precipitate is a solid that forms out of a solution.

∙

A common example is that of the mixing of two clear solutions: Silver nitrate

(A g N O_{3})

and sodium chloride

(N a C l)

:

A g N O_{3} (a q) + N a C l (a q) \to A g C l (s) ↓ + N a N O_{3} (a q)

The precipitate forms because the solid

(A g C l)

is insoluble in water.

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NCERT Solutions for Class 10 Chemistry Chapter 1 : Chemical Reactions and Equations

NCERT Solutions for Class 10 Science Chapter 1 Chemical Reactions and Equations – Brief Overview

Chemical reactions play a significant role in our daily lives. All chemical changes are linked to chemical reactions, which are expressed mathematically through equations. In this section, we will look at the many types of chemical changes denoted by chemical reactions and chemical equations.

1. Chemical Reactions

A chemical reaction is a process that converts one or more substances, and reactants into one or more new compound substances with completely different properties. Reactants are substances that react, such as molecules, ions, and atoms.

Example:

Hydrogen + Oxygen → Water

In the above chemical reaction, Hydrogen and Oxygen are the reactants and Water is the product formed due to the reaction.

2. Chemical Equations

A chemical equation is a symbolically represented chemical reaction in the form of symbols and formulae, with the reactant entities on the left and the product entities on the right and both separated by an arrowhead pointing towards the products representing the direction of the reaction. The reactants and the products are written with a plus sign (+) between them.

Example:

H₂ + O₂ → H₂O

As you can see, the number of atoms in the reactants and products in the preceding equation is not the same on both sides. A skeleton chemical equation is a type of imbalanced equation.

3. Balancing Chemical Equations

A balanced chemical equation is one in which the total number of atoms of each element on both sides of the equation is equal. The Law of Conservation of Mass states that "mass can neither be created nor destroyed during a chemical reaction," which means that the total mass of the elements present in the products of a chemical reaction must match the total mass of the elements present in the reactants.

Example: To balance the above equation

H₂ + O₂ → H₂O

We choose the element which is unbalanced. It is Oxygen in the reactant side.

No. of atoms of Oxygen in Reactant is 2 and Product is 1, so we multiple product H₂O by 2.

H₂ + O₂ → 2H₂O

Now, No. of atoms of Hydrogen in the Reactant is 2 and the Product is 4, so we multiple reactant H₂ by 2.

2H₂ + O₂ → 2H₂O

Since the number of atoms of reactants and products is equal, the chemical equation is balanced.

4. Types of Chemical Reactions

Combination Reaction - Combination reactions occur when two or more elements react to generate a new single product. For example,

H₂ + Cl₂ → 2HCl

Decomposition Reaction – Decomposition reactions occur when a single reactant breaks down into several products. For example,

CaCO₃ → CaO + CO₂

Displacement Reaction - The displacement reaction occurs when a more reactive element replaces a less reactive element in a compound. For example,

Fe + CuSO₄ → FeSO₄ + Cu

Double displacement Reaction - It is a kind of chemical reaction in which two compounds react and their positive and negative ions exchange positions to generate new products. For example,

Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl

Oxidation and Reduction Reaction - An oxidation reaction occurs when a substance receives oxygen or loses hydrogen during a reaction. A reduction reaction occurs when oxygen is lost and hydrogen is gained from a substance during a process. For example,

2Zn + O₂ → 2ZnO

CuO + H₂ → Cu + H₂O

Redox Reaction - Redox reactions are chemical processes that occur when both oxidation and reduction occur at the same time. For example,

CuO + H₂ → Cu + → Cu + H₂O

Related Chapters

Chapter 2 : Acids, Bases and Salts

Chapter 3 : Metals and Non metals

Chapter 4 : Carbon and its compounds

Chapter 5 : Periodic Classification of Elements

Chapter 6 : Life Processes

Chapter 7 : Control and Co-ordination in Plants and Animals

Chapter 8 : Reproduction

Chapter 9 : Heredity and Evolution

Chapter 10 : Light- Reflection and Refaction

Chapter 11 : The Human Eye and colourful World

Chapter 12 : Electricity

Chapter 13 : Magnetic Effect of Electric Current

Chapter 14 : Sources of Energy

Chapter 15 : Our Environment

Chapter 16 : Management of Natural Resources

Frequently Asked Questions on NCERT Class 10 Chemistry Chapter 1 : Chemical Reactions and Equations

Q1. What is meant by chemical reactions and equations?

Answer: A chemical reaction is a process that converts one or more substances, and reactants into one or more new compound substances with completely different properties. A chemical equation is a symbolic representation of the reaction using formulae, with reactants on the left and products on the right.

Q2. Give an example of a double displacement reaction.

Answer: CuSO₄(aq) + 2NaOH(aq) → Cu(OH)₂(s) + Na₂SO₄(aq)

Q3. What is a balanced chemical equation? Why should chemical equations be balanced?

Answer: A balanced chemical equation is one in which the total number of atoms of each element on both sides of the equation is equal. Atoms, according to the rule of conservation of mass, cannot be formed or destroyed. To comply with this universal law, the equation must be balanced so that the total atoms on the left side equal the total atoms on the right side.

Related Chapters

Chapter 2 : Acids, Bases and Salts

Chapter 3 : Metals and Non metals

Chapter 4 : Carbon and its compounds

Chapter 5 : Periodic Classification of Elements

Chapter 6 : Life Processes

Chapter 7 : Control and Co-ordination in Plants and Animals

Chapter 8 : Reproduction

Chapter 9 : Heredity and Evolution

Chapter 10 : Light- Reflection and Refaction

Chapter 11 : The Human Eye and colourful World

Chapter 12 : Electricity

Chapter 13 : Magnetic Effect of Electric Current

Chapter 14 : Sources of Energy

Chapter 15 : Our Environment

Chapter 16 : Management of Natural Resources