Checking the Balance of Simple Equations
Steps in Solving it
1.
2.
3.
4.
5.
What elements are on the reactant side.
How many atoms of each element are on the reactant side?
What elements are on the product side?
How many atoms of each element are on the product side?
Is this equation balanced?
C (s) + O 2(g)  CO 2(g)
Let’s try another…
FeO (s)  Fe (s) + O 2(g)
There are two numbers that you need to pay attention to in
determining the number of atoms in a molecule.
Subscript - O2
Coefficient – 2MgO
2H2
Example:
CH 4(g) + 2O 2(g)  CO 2(g) + 2H2O (g)
Is this equation balanced?
6CO 2 + 6H 2O + energy  C6H12O6 + 6O2
What is this an equation for?
Sample Problem
When methane gas and oxygen gas are combined, they react to form carbon
dioxide and water. The chemical equation for this is:
CH4(g) + O2(g)  CO2(g) + H2O(l)
Outline the steps to balance this equation.
Steps in Solving It
1.
Start by balancing everything except H and O. In other words, start by
balancing the atoms of C (carbon).
CH4(g) + 2O2(g)  CO2(g) + 2H2O(l)
1 carbon
1 carbon
There is one atom of carbon on each side of the equation. Therefore, the carbon
atoms are already balanced.
2.
Now balance the atoms of hydrogen (H) in the equation.
CH4(g) + 2O2(g)  CO2(g) + 2H2O(l)
4 hydrogen
2 H2
(H + H) + (H + H)
4 hydrogen
There are 4 atoms of hydrogen on the reactant side, and 4 atoms of hydrogen
on the product side. Therefore, the hydrogen atoms are balanced.
3. Finally, balance the atoms of oxygen (O) in the equation.
CH4(g) + 2O2(g)  CO2(g) + 2H2O(l)
2 O2
O2
2 O
left side = 2 oxygen + 2 oxygen
right side = 2 oxygen + 2 oxygen
= (O + O) + (O + O)
= (O + O) + (O + O)
= 4 oxygen
= 4 oxygen
There are 4 atoms of oxygen on the reactant side, and 4 atoms of
oxygen on the product side.
Therefore, the oxygen atoms are balanced.
4.
Is this equation balanced?
reactant side = 1 atom of carbon, 4 atoms of hydrogen, and 4 atoms of
oxygen
product side = 1 atom of carbon, 4 atoms of hydrogen, and 4 atoms of
oxygen
Yes, the equation is balanced.
Types of Chemical Reactions
Simple composition –
Simple decomposition –
Combustion –
Neutralization –