EXERCISES II
As in the first balancing exercises, you will need
to use the calculator below and click on the UNDO button until the
formula entry window is clear.
1. Enter the equation:
C6H12O6 + O2 => CO2 + H2O by typing #J? and hitting SUBMIT.
Note that C and H occur only once on each side so they may be balanced
first. Once that is done, the coefficient of O2 achieves a balance for O.
Also note that O occurs by itself in O2 and that is why we choose the
coefficient for O2 last.
2. Enter the equation:
CH4 + O2 => CO2 + H2O by typing #F? and hitting SUBMIT.
The balance procedure here is similar to the exercise above.
Choose the coefficient for O2 last.
3. Enter the equation:
CH4 + Br2 => CBr4 + HBr by typing #O? and hitting SUBMIT.
You should balance H first because it occurs once on each side but
also because Br2 is by itself on the left side and it can be adjusted
last to take up any unbalance of Br.
4. Enter the following reaction for nitroglycerin:
C3H5N3O9 => N2 + CO2 + H2O + O2 by typing #X? and hitting SUBMIT.
Carefully balance N, C, and H on the right side using fractions if
necessary while keeping the coefficient on the left side equal to one.
Leave O2 on the right side for last because there O occurs by itself.
Subtract the amount of O in CO2 and H2O from the O of C3H5N3O9.
You will need to use fractions.
The resulting difference should be divided by 2 so it can be multiplied by
O2. That becomes the coefficient of O2. Try it and see if you have a
balance. Then
multiply the equation by the least common multiple of all the fraction's
denominators. The least common multiple is the smallest integer that all
the denominators will divide into.
If you solve this one, then congratulations - you are
becoming an expert.
5. Enter the equation:
Mg(OH)2 + HNO3 => Mg(NO3)2 + H2O by typing #Z? and hitting SUBMIT.
This equation can be difficult
because H occurs in two places on the left
side and O occurs in two places on both sides. The hint here is to balance
the elements in order of difficulty. Mg is already balanced. N is the next
easiest to balance because it occurs only once on each side. H is next in
difficulty and O is the worst in difficulty as mentioned above.
This is one of the most difficult equations
to balance in this tutorial
so if you can balance this one, you are doing quite well.
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