 # AP Class 10 Physical Science Chapter 2 Chemical Reactions and Equations

Chapter 2 Chemical Reactions and Equations of Andhra Class 10 Physical Science discusses chemical change and their representation in the form of a chemical equation.

## What is a Chemical Reaction?

A chemical reaction is a process in which the reactants are converted to one or more different substances. A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products. Different types of chemical reactions are as follows:

• Combination Reaction – Two or more substances combine to form a new single substance.
• Decomposition Reaction – A single reactant decomposes into two or more substances.
• Endothermic Reaction – Reaction in which heat is absorbed by the reactants.
• Exothermic Reaction – Reaction in which heat is released by the reactants.
• Displacement Reaction – When an element displaces another element from its compound.

### What is a Chemical Equation?

A chemical equation is the symbolic representation of a chemical reaction with reactants on the left side of an arrow and the products of the chemical reaction on the right. A complete chemical equation represents the reactants, products and their physical state. A chemical equation must always be balanced. It is said to be balanced when the number of atoms of each element is the same on both the reactants and products side.

## Class 10 Science Chapter 2 Chemical Reactions and Equations Questions

1. Balance the following chemical equations.
2. $NaOH+H_{2}SO_{4}\rightarrow Na_{2}SO_{4}+H_{2}O$
3. $H_{2}+O_2\rightarrow H_{2}O$

Solution:

1. $NaOH+H_{2}SO_{4}\rightarrow Na_{2}SO_{4}+H_{2}O$ can be balanced as
$2NaOH+H_{2}SO_{4}\rightarrow Na_{2}SO_{4}+2H_{2}O$
1. $H_{2}+O_2\rightarrow H_{2}O$ can be balanced as $2H_{2}+O_2\rightarrow 2H_{2}O$

2. Why is respiration considered as an exothermic reaction? Explain.

Solution:

An exothermic reaction is a reaction in which energy in the form of either light or heat is released. Respiration is considered an exothermic reaction because energy is released in this process. Glucose combines with oxygen present in our cells to form carbon dioxide and water along with energy.

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