Page 84 - Chemistry_Form_2

Chemistry
for Secondary Schools

Chapter

Four Chemical reactions

FOR ONLINE READING ONLY

Introduction

Chemical reactions are an integral part of daily life, constantly occurring in and
around us, often unnoticed. For example, everyday activities such as burning
charcoal and wood, cooking food, respiration in living organisms, fuel combustion
in engines, rusting of metals, and digestion involve transforming substances into
new ones. These transformations result from chemical reactions. In this chapter,
you will learn the concept of chemical reactions, including chemical equations,

and types of chemical reactions. The competencies developed will enable you to
accurately present chemical equations and analyse various chemical reactions
that yield products essential to daily life.

Think

The impact of chemical reactions on natural and industrial processes

Concept of chemical reactions

Task 4.1

Use library books and reliable online resources to search for any five chemical
reactions that occur in daily life. For each response, include the name of the
chemical reaction, a brief explanation of how it happens, the chemical equation
(if applicable) and an example of where this reaction is frequently observed.

A chemical reaction is a process in which one or more chemical substances
are converted to one or more different substances. Chemical reactions take
place when bonds between atoms in the reacting substance(s) are broken,
atoms rearrange, and new bonds between the atoms are formed to make new
substance(s). The chemicals that begin the reaction process are called reactants
and the new substances formed are called products. The products have properties
that are different from their respective reactants. Features that indicate a chemical
reaction has taken place include one or more of the following: evolution of a
gas; formation of precipitates; and change in colour, temperature or state.

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