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Tutorial Index

Introduction to Elements, Atoms, Molecules, Compounds and Chemical Bonding
Introduction to Chemical Bonding
Metals, Non-metals and Compounds
Non-metal Radical Groups
Names of Acids and other compounds
Introduction to Chemical Reactions, the Rules and the products of a reaction
Types of Chemical Reactions I
Types of Chemical Reactions II
Introduction to the Periodic Table
Using Chemical Formulae

The Chapters Index

 

Equations using symbols and formulae

After working through the five examples on this page, complete the two tasks shown below.

 

Test Yourself
(Opens in a new window)

Exercise IX
(Opens in a new window)

 

 

 

THE LANGUAGE OF CHEMISTRY

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Equations using symbols and formulae

We can use the chemical symbols and formulae to construct chemical equations for the reactions we have met in the tutorials.

Example 1 :

 

Reaction01

The first step is to write the correct formulae:

 

Equation 1

 

The equation is not balanced. Have you noticed that there are two oxygen atoms on the reactants' side of the equation and only one on the products' side?

Look at the image equation. You will see that we need two hydrogen sulfide molecules, two sulfur atoms and two water molecules. So we need to balance the equation. This is achieved by placing a whole number in front of the symbol or formula. Never try to balance the equation by changing a formula in some way.

 

Equation 2

 

Congratulations! You have written your first chemical equation using symbols and formulae. Before you work through some more examples just check again that you have the same number of each type of atom on both sides of the equation.

Remember:

"Matter can neither be created nor destroyed by chemical means"

 

Example 2 :

Reaction02

The first step is to write the correct formulae:

 

Equation 4

 

Before you work through some more examples just check again that you have the same number of each type of atom on both sides of the equation.

 

Example 3 :

Reaction03

The first step is to write the correct formulae:

 

Equation 4

 

Before you work through the last two examples just check again that you have the same number of each type of atom on both sides of the equation. Everything in brackets () is multiplied by the number outside the brackets.
In this case the number of oxygen atoms in calcium nitrate is 3 x 2 = 6
The number of nitrogen atoms is 1 x 2 = 2

 

Example 4 :

Reaction04

 

Equation 5

 

Example 5 :

Reaction05

 

Equation 6

 

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