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Home
Science
Chemical Equations

Chemical Equations

Explaining chemical equations in simple words - “It is a way to represent different chemical reactions and formulas in a symbolic form”. It is very important to learn how to write and read chemical equations to be able to understand many concepts of chemistry. Chemical equations show the various reactants and products involved in a reaction, as well as the direction in which the reaction takes place. 

A balanced chemical equation can help us learn about the following aspects of a reaction: 

  • Reactants and Products: The chemical materials at the beginning of the reaction and their end products can all be identified through a chemical equation.
  • Stoichiometry: A chemical equation can also show the relative amounts in which the reactants are present in the equation. Through this, we can easily predict how much product will be formed. 
  • Physical States: We can determine whether the substances present in a chemical reaction are in solid, liquid, or gaseous states by reading their equations. 
  • Reaction Conditions: In some cases, information about the conditions present during a reaction, such as the temperature or pressure, may be included in the chemical equation.

Chemical Equations of Reactants and Products

1.0Components of a Chemical Equation

A chemical equation is usually written in this manner: 

Reactants → Products

These are the different components present in it: 

Component

Description

Example (using 2H₂(g) + O₂(g) → 2H₂O(l))

Reactants

These are the different chemical substances that react with each other. These are usually written on the left side of the equation. 

H₂, O₂

Products

The products are the substances that are formed due to the reaction of the reactants. 

H₂O

Arrow (→)

An arrow helps indicate the direction in which a reaction takes place. 

→

Double Arrow (⇌)

A double arrow may be used in cases of reversible reactions. 

⇌

Coefficients

Coefficients are the numbers put before the formulas that signify the mole ratios in which each substance is present. 

2 (in 2H₂), 1 (in O₂), 2 (in 2H₂O)

Subscripts

Subscripts are the numbers within the formula. These show the atoms of each element. 

2 (in H₂), 2 (in O₂), 2 (in H₂O)

Symbols

Symbols like (s),(l), or (g) are used to show the physical state of the substances. 

(g) for H₂, (g) for O₂, (l) for H₂O

Example:

2H₂(g) + O₂(g) → 2H₂O(l)

Through this equation, we can know that two molecules of hydrogen gas (H₂) react with one molecule of oxygen gas (O₂) to produce two molecules of liquid water (H₂O).

2.0Balancing Chemical Equations

The Law of Conservation of Mass mentions that matter cannot be created or destroyed in a chemical reaction. And so, the number of atoms present on both sides of a chemical equation should be the same. Balancing chemical equations is essential in order to adhere to this law. An equation that does not follow this would be an unbalanced chemical equation.

Unbalanced Chemical Equations Examples:

Fe + O₂ → Fe₂O₃

C₂H₆ + O₂ → CO₂ + H₂O

Steps for Balancing Chemical Equations:

  1. Write down the unbalanced equation as it is. 
  2. Make a note of the elements that have a different number of items on each side of the equation. These are the elements that are not balanced. 
  3. Start by balancing one element at a time, with the most complex molecule first. Use coefficients to adjust the number of molecules.
  4. Keep repeating this step until you have balanced all the elements. Make sure to recheck the balance of other elements as you adjust coefficients.
  5. If possible, simplify the coefficients by reducing them to the lowest whole number ratio.

Practising some balancing chemical equations can help make the process much easier.

Balance Chemical Equations Examples:

Unbalanced Equation

Balanced Equation

CH₄ + O₂ → CO₂ + H₂O

CH₄ + 2O₂ → CO₂ + 2H₂O

KClO₃ → KCl + O₂

2KClO₃ → 2KCl + 3O₂

3.0Solved Problems 

Q1. Balance the following chemical equation: H₂ + O₂ → H₂O

Solution:

Unbalanced: H₂ + O₂ → H₂O

Balance Oxygen: H₂ + O₂ → 2H₂O (Now there are 2 oxygen atoms on both sides)

Balance Hydrogen: 2H₂ + O₂ → 2H₂O (Now there are 4 hydrogen atoms on both sides)

Balanced: 2H₂ + O₂ → 2H₂O

Q2. Balance the following chemical equation: C₃H₈ + O₂ → CO₂ + H₂O

Solution: 

Unbalanced: C₃H₈ + O₂ → CO₂ + H₂O

Balance Carbon: C₃H₈ + O₂ → 3CO₂ + H₂O

Balance Hydrogen: C₃H₈ + O₂ → 3CO₂ + 4H₂O

Balance Oxygen: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

Balanced: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

4.0Types of Chemical Equations

Chemical occasions can be divided based on the type of reactions that they represent. Some common types of chemical equation include:

Type of Reaction

General Form

Chemical Equation Example

Combination

A + B → AB

2Na + Cl₂ → 2NaCl

Decomposition

AB → A + B

2KClO₃ → 2KCl + 3O₂

Single Replacement

A + BC → AC + B

Zn + 2HCl → ZnCl₂ + H₂

Double Replacement

AB + CD → AD + CB

AgNO₃ + NaCl → AgCl + NaNO₃

Combustion

Fuel + O₂ → CO₂ + H₂O (often with heat/light)

CH₄ + 2O₂ → CO₂ + 2H₂O

Chemical Equation and Reaction

A chemical equation and a chemical reaction are two concepts that are intertwined with each other, as a chemical equation describes a chemical reaction. At a chemical equation and reaction class 10 level, balanced chemical equations are used to calculate quantities of reactants and products. 

For example, the chemical equation for photosynthesis can help you understand the reaction that takes place: 

6CO₂(g) + 6H₂O(l) → C₆H₁₂O₆(s) + 6O₂(g)

This equation shows how carbon dioxide and water are converted into glucose (a sugar) and oxygen using sunlight as energy.

Table of Contents


  • 1.0Components of a Chemical Equation
  • 2.0Balancing Chemical Equations
  • 3.0Solved Problems 
  • 4.0Types of Chemical Equations

Frequently Asked Questions

It is important to follow the Law of Conservation of Mass when writing a chemical equation. This law states that matter can neither be created nor destroyed during a reaction.

Coefficients show the number of molecules involved in a reaction, while subscripts show the number of atoms in a molecule.

A balanced equation will have the same number of each type of atom on both sides of the equation, whereas an unbalanced equation will not.

A double arrow shows a reversible reaction, which means that the reaction can go in both directions.

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