Download Balancing Chemical Equations

Balancing Chemical Equations
Remember: In a chemical reaction, atoms are neither
created nor destroyed.
 In other words, if you have a certain amount of an element in the beginning,
then you have to have the same amount in the end. Likewise if you have it at
the end you had to of had it at the beginning.
 Here are the basic steps to follow when balancing equations. You should
always use pencil when balancing equation so that you can erase any mistakes.
1st  Count the atoms of each element on each side of the arrow in an
equation.
Ex. CH4 + O2  CO2 + H2O
C=1
C=1
H=4
H=2
O=2
0=3
2nd We need to add compounds to get equal numbers of each
element. You can only add whole amounts of a molecule. You can only
add compounds that were in the original equation. You CANNOT add
single atoms to balance the equation unless the element is in the
original equations as a single atom. Think of this as a recipe and you
can’t just start adding ingredients and expect the same result from the
recipe.
Ex. CH4 + O2 + O2  CO2 + H2O + H2O
C=1
C=1
H=4
H=4
O=4
O=4
The correct way to write this is to put a coefficient to represent
multiple molecules or formula units. You can only add coefficients to
balance an equation. You can never change the subscripts. This would
change the identity of that compound. A coefficient is placed before a
molecule. A coefficient pertains to every element in the compound,
regardless of parenthesis. The example below is telling us that there are
2 oxygen molecules (O2) in the reactants. That is a total of 4 oxygen
atoms.
Ex.
CH4 + 2O2  CO2 + 2H2O
C=1
C=1
H=4
H=4
O=4
O=4
 The equation is now balanced because there are equal
amounts of carbon, hydrogen, and oxygen on the reactant
side and on the product side.
3rd The last step is to make sure that the coefficients are the lowest
whole numbers possible.
Ex. 2CH4 + 4O2  2CO2 + 4H2O can be reduced to CH4 + 2O2  CO2 + 2H2O
*This is a trial and error type of process. You will need to use pencil because you
may have to try many times before you get the correct answer. Don’t give up. If
one problem is giving you trouble, skip it and move to the next one. Then come
back to that problem and try it again.