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Ask a Teacher - Chemistry - Formulae and Equations - A Question from Michael
Student Name
Michael
Question
I am stuck on how to balance equations and I don't understand
how it works. Please could you write back and explain in greater
detail how to balance equations?
Answer
An equation is said to be balanced when there are equal numbers
of atoms on each side of the equation. This is logical because you
cant lose atoms. The way the atoms are combined on the product
side will be different to the reactant side, but thats what
chemistry is all about ! Remember you cant change a formula
to balance up atoms. Numbers are put in front of formulae.
This is best shown in a example:
hydrogen
+ chlorine
hydrogen
chloride
Unbalanced
equation
H2
+ Cl2
HCl
Left: H atoms = 2 Cl atoms
= 2 Right: H atoms = 1 Cl atoms = 1
There seems to be one H atom and one Cl atom missing
from the right. They must have formed another HCl molecule as HCl
is the only product.
This could be written as:
H2
+ Cl2
HCl
HCl
but it is easier to write
H2
+ Cl2
2
HCl
This is the balanced equation.
Most Standard Grade
texts will have worked examples and questions.
