Chemical Reaction and Equations

Chemical Reaction and Equations
January 29, 2023

Since the dawn of time, chemical reactions have taken place. But it was the chemists who first learned about them in the 18th century, and it was then that they began to study and understand them. Although fermentation, a process where sugar is turned into alcohol, has been around for millennia, the molecular underpinnings of the reaction were not understood at the time.

Chemical reactions place all around us without our even realising it. In this process, the bonds between the molecules of the reactants and products are broken, and new bonds are formed. Chemical reactions are all around us and may take many different forms, such as the breakdown of sugar or the evaporation of water. Chemical processes can take various forms, including synthesis, breakdown, single-replacement, combustion, reduction-oxidation, double displacement, and acid-base reactions; in this blog post, all the concepts of chemical reaction and equations will help you to score high grades in your Chemistry examination.

What are Chemical Reactions?

The complete process of a chemical substance changing into another is known as a chemical reaction. These are the chemical reactions in which bonds between various atoms are formed or broken (or both), transforming reactants into products.

Chemical reactions may be found in many everyday processes, such as rusting iron and making curd from milk. A new material with wholly different characteristics from the original one is produced when a chemical reaction occurs.

Example of Chemical Reactions

A great illustration of the physical and chemical transformation is a burning candle. Light a candle if you have one. You can see the candle melt and transform into wax as time passes. The identical candle will go out if a jar is used to cover the candle. As a candle burns, a chemical change occurs, and a physical change—the candle becoming wax. A substance's condition largely changes as a result of a physical change. On the other hand, a chemical change primarily causes the formation of a new material in which energy is released or absorbed. We may conclude as a result that physical changes occur after chemical changes.

Basic Concept of the Chemical Reaction

The following are the basic concepts of the chemical reactions:

  • When two or more molecules of two different substances interact, a new product may be produced. This process is known as a chemical reaction.
  • Reactants are chemical substances that interact to make new compounds, and products are those newly produced chemicals.
  • In many industries, as well as in cooking and other daily activities, chemical reactions are crucial. In nature, several chemical processes such as rusting iron, grape fermentation into wine, and others frequently occur.
  • With the occurrence of the chemical reactions, there must be chemical change with the physical change such as state, colour, heat production, precipitation etc.
  • Temperature, pressure, reactant concentration, and other internal and external factors affect how quickly a reaction happens.
  • A new product can still be produced from the reactants even when no atoms are destroyed or formed in a reaction between two atoms that forms a new bond.

Importance of Chemical Reaction

A chemical reaction is crucial for the existence of life on Earth. The following are the reasons why chemical reactions are important:

  • To comprehend the qualities of the substance, chemical processes are necessary. These reactions aid in understanding the chemical characteristics that emerge when a sample interacts with a substance. These chemical characteristics can explain how various forms of materials interact with one another and point to previously unidentified species.
  • Understanding how the natural world functions are possible by researching and watching chemical reactions. Food changes shape when cooked, makes fireworks burst, transforms into fuel in the human body, and causes soap to wash away oil and grime due to a chemical reaction.
  • Fire, the most significant and advantageous discovery ever made by humanity, is a byproduct of straightforward chemical processes.
  • Scientists take the help of the chemical reaction to study outer space and other planets.

Students must grasp each chapter concept to score good marks in class 10 Science. The chapter is important regarding the board examinations and competitive examinations such as NDA, AFCAT, CDS, IIT JEE, NTSE etc.

Direction of Chemical Reaction

The arrow between the reactants and products is customarily supposed to point from left to right. But when necessary in an equation, the following symbols are used:

  • The symbol "is used to represent a net forward response.
  • The symbol "" is used to represent a condition of chemical equilibrium.
  • The sign "=" is used to indicate stoichiometric relationships.
  • The symbol "" represents a response that happens both forward and backward.
  • The sign "+" indicates the separation of different entities in a chemical equation.

Physical State of Reacting Entities

The following symbols can be used to indicate the physical states of responding entities during reaction:

  • The solid-state sign (s)
  • The liquid condition is indicated by the letter (l).
  • A gaseous condition is implied by the symbol (g).
  • An aqueous solution is indicated by the sign (aq).

Additionally, in some reactions, residues are indicated by the symbol "↓" next to the chemical formula of the reactant or product.

Properties of Chemical Reaction

The following are the characteristics of the which aid in identifying the occurrence of  chemical reaction:

1. Evolution of Gas

As a gas or a combination of gases evolves, several chemical processes occur. For instance,

Lead nitrate decomposes when heated, releasing gases such as nitrogen, dioxide and oxygen together with a solid residue of lead monoxide.


2. Change in Temperature

For instance, heat is generated when quicklime (calcium oxide) and water are handled in a beaker. The beaker thus heats up considerably. Exothermic reactions are those that result in the production of heat.


The bottom of the test tube turns chilly when ammonium chloride and barium hydroxide are combined and agitated with a glass rod. Heat is absorbed in this process. An endothermic reaction is what is known as such a reaction.


3. Change in State

A change in their physical state is a characteristic of several chemical processes.

For instance, a change in the physical state distinguishes the combustion response of the wax candle. Wax liquid and carbon dioxide were produced during candle combustion. Here, carbon dioxide is a gas, and wax is a solid that becomes liquid when heated. As a result, it demonstrates how wax tra\nsforms physically during candle burning, going from a solid to a liquid and then a gas (carbon dioxide).

4. Formation of a Precipitation

Few chemical reactions are also characterised in terms of the formation of precipitation.

A blue copper hydroxide precipitate is produced as a result of the chemical reaction between copper
sulphate and sodium hydroxide.

Na2SO4 + Cu(OH)2 CuSO4 + 2NaOH

A white precipitate of silver chloride is produced as a result of the chemical reaction between silver
nitrate and sodium chloride.

NaNO3 + AgCl AgNO3 + NaNO3

5. Change in Color

A colour change can be observed in a few chemical reactions:

When colourless potassium iodide solution was put into chlorine water, a dark solution resulted (yellowish).


Understand What is Chemical Equation?

Chemical equations are a symbolic representation of the reaction that will occur when two or more components are brought together. To meet all requirements, including the rule of conservation of matter, chemical equations must be balanced.

Elements on the right side of an arrow are the product, while the number of elements on the left side is the reactant (or resultants). When the number of atoms of an element on the reactant side and the number of atoms of elements on the product side is equal, the equation is said to be balanced.

Example for Chemical Equation

In order to create sodium nitrate (NaNO3[aq]) and silver chloride, two aqueous solutions of sodium chloride (NaCl[aq]) and silver nitrate (AgNO3[aq]) are combined (AgCl[s]).

The following will serve as the symbol:

NaCl(aq) + AgNO3(aq) → NaNO3(aq) + AgCl(s)

Let us take the other example to demonstrate the idea of the chemical equation.

Photosynthesis is known to turn carbon dioxide and water into glucose and oxygen in plants and certain other organisms.

6CO2 + 6 H2O → C6H12O6 + 6O2


Carbon dioxide is represented as CO2.

Water is represented as H2O.

Light is essential for photosynthesis.

Glucose is symbolises as C6H12O6

Oxygen is symbolised as O2.

Types of Chemical Reactions

The following are the different types of chemical reactions:

  • Combination reactions: These reactions involve the combining of two or more reactants to produce a single result.
  • Decomposition Reaction: Decomposition Reactions are those in which one component is broken down into two or more other compounds or elements.
  • Thermal Decomposition: When a material breaks down after being heated, this process is referred to as thermal decomposition.
  • Electrolytic Decomposition: This term refers to reactions in which substances break down into simpler substances due to the passage of electricity. Electrolysis is another name for this.
  • Photolysis or Photo Decomposition Reaction: When sunshine is present, a chemical breaks down in a photolysis or photodecomposition process. The terms "photolysis" and "photodecomposition reaction" describe this phenomenon.
  • Single Displacement Reaction: Displacement reactions are chemical reactions in which a more reactive ingredient removes a less reactive element from a molecule. They are also known as Replacement Substitution Reaction Reactions.
  • Double Displacement Reaction: Double Displacement Reactions are reactions in which ions are transferred between two reactants, forming new compounds.
  • Precipitation Reaction: The reaction that takes place when an aqueous solution of two salts is combined to generate a residue is known as a precipitation reaction.
  • Neutralisation Recreation: The process of an acid reacting with a base to produce salt and water through the exchange of ions is known as a neutralisation reaction.
  • Reactions of Oxidation and Reduction: Oxidation is the process of either introducing oxygen or a non-metallic element into a compound or removing hydrogen or a metallic element from it. A reduction reaction is one in which a reactant obtains one or more electrons.

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