Chemistry Reference
In-Depth Information
We notice that our equation is not balanced. The number of carbon
atoms on each side of the equation is the same, but we have twice as many
hydrogen atoms on the left-hand side, and there is an additional oxygen
atom on the right-hand side. Let's start by adding a coefficient of “2” to the
water on the product side, in an attempt to balance the hydrogen atoms.
Then, we will do another atomic tally to see where we are. To make this
easier to follow, I will put the coefficients that I add in bold and italics.
CH
4
+ O
2
2H
2
O + CO
2
Elements
{
# of atoms
{
CHOCHO
142144
Not balanced!
Notice the new tally. By putting the coefficient in front of the water
(H
2
O) I not only changed the number of hydrogen atoms on the product
side, I also changed the number of oxygen atoms. Now we have twice as
many oxygen atoms on the right-hand side as on the left-hand side. It should
be as simple as adding another coefficient of “2,” this time in front of the
oxygen on the reactant side. Let's do that, and do another atomic tally.
CH
4
+ 2O
2
2H
2
O + CO
2
Elements
{
# of atoms
{
CHOCHO
144144
Balanced!
Do you see how the skills of performing an atomic tally and balancing
equations go hand in hand? To be able to do one, you need to be able to do
the other. Let's try one more example together. Take a look at Example 4
and see how far you can go before you check my answer.
Example 4
Do an atomic tally for the following equation and determine if it is
balanced. If not, balance the equation using coefficients and repeat
the tally.
KClO
3
KCl + O
2
In the first step, I will do an atomic tally to get an idea of what to do next.
