Problem 1 : Example balancing equations:
Balance the chemical equation for combustion of penthane
Balance, step by step Problem 1: Balance
the equation for the combustion of pentane
Step 1. Insert 1 in front of the most complicated looking
compound.
1C5H12 + O2 -->
CO2 + H2O
Step 2. To balance C's, 5 must be inserted in front of CO2.
1C5H12 + O2 -->
5CO2 + H2O
Step 3. To balance H's, 6 must be inserted in front of H2O
.
1C5H12 + O2 -->
5CO2 + 6H2O
Step 4. To balance O's, 8 must be inserted in front of O2 .
1C5H12 + 8O2 =
5CO2 + 6H2O
Erase 1 from the equation:
C5H12 + 8O2 =
5CO2 + 6H2O
The equation is now balanced!
Note: If any fractions should occur, simply multiply the equation
by a suitable number. This will be demonstrated in the next
problem.
The algebraic solution to Problem 1: How to balance the equation for the combustion of pentane ( C5H12 )
Step 1. Insert coefficients in front of the all compounds.
aC5H12 +
bO2 --> cCO2 +
dH2O
C:
5a = c
let a = 1
-> c = 5*1
= 5
H: 12a = 2d
we know that a=1
-> d = (12*1)/2
= 6
O: 2b = 2c +
d we know that a = 1 and d =
6
-> b = (2c + d)/2 =
(2*5+6)/2 = 8
C5H12 + 8O2 --> 5CO2 + 6H2O
Figure:
How to balance the combustion of ethane. Note:
Picture from an older CHEMIX School version
Figure: The Formation Of Water - Balancing Chemical Equation
Example - CHEMIX School
Problem 2: Balance the equation
for the combustion of ethane
Step 1. Insert 1 in front of the most complicated looking
compound.
1C2H6 + O2 -->
CO2 + H2O
Step 2. To balance C's, 2 must be inserted in front of CO2.
1C2H6 + O2 -->
2CO2 + H2O
Step 3. To balance H's, 3 must be inserted in front of H2O
.
1C2H6 + O2 -->
2CO2 + 3H2O
Step 4. To balance O's, 7/2 must be inserted in front of O2 .
1C2H6 + 7/2O2 =
2CO2 + 3H2O
Step 5. Eliminate the fraction 7/2. This can be done by
multiplying the equation by 2.
2C2H6 + 7O2 =
4CO2 + 6H2O
The equation is now balanced!
The algebraic solution to Problem 2:
How to balance the equation for the combustion of ethane
( C2H6 )
Step 1.
Insert coefficients in front of the all compounds.
aC2H6 +
bO2 --> cCO2 +
dH2O
C: 2a =
c
let
a = 1
-> c = 2*1
= 2
H: 6a = 2d
we know that a=1
-> d = (6*1)/2
= 3
O: 2b = 2c +
d
we know that c = 2 and d = 3
-> b = (2c + d)/2 =
(2*2+3)/2 =7/2
1C2H6 + 7/2O2 = 2CO2 + 3H2O
The equation is now in balance but we have to eliminate the fraction 7/2. This can be done by multiplying the equation by 2.
2C2H6 + 7O2 = 4CO2 + 6H2O
Figure: How to balance the combustion of
ethane.
Tab. Guidelines for balancing equations using the CHEMIX School
program
Sign/symbol | Example | Interpretation |
---|---|---|
+ | H2 + O2 .... | Separates compounds in equations |
> | H2 + O2 > H2O | Separates left and right side (normally an arrow) |
e- | Cu + H2O > Cu2O + H+ + e- | Electron |
CHEMIX
School
- Balancing chemical equations
Balancing Chemical Equations - Examples from CHEMIX School program
1) FeS2+O2>Fe3O4+SO2
2) C3H8+O2>CO2+H2O and calculate the amount of CO2 and H2O formed if 2 grams of C3H8 (propane) reacts with O2.
3) C3H8+O2>CO2+H2O and calculate the amount of CO2 and H2O formed if 2 moles of C3H8 (propane) reacts with O2.
4) C3H8+O2>CO2+H2O and calculate the amount of CO2 and H2O formed if 5 grams of C3H8 (propane) reacts with 3 grams of O2.
5) C3H8+O2>CO2+H2O and calculate the amount of CO2 and H2O formed if C3H8 (propane) containing 2 grams of H reacts with 3 grams of O2.
6) As2S3+NaNO3+Na2CO3>Na3AsO4+Na2SO4+NaNO2+CO2 and calculate the amount of As2S3 used forming CO2 containing 10 grams of carbon.
How to download CHEMIX School for balancing equations
For downloading CHEMIX School - simply click the
download link at the top of this page. There is more to CHEMIX
School than balancing chemical equations. Examples of other
tools integrated in CHEMIX School chemistry program are: Molecular
weight calculator, periodic table, solubility product calculator,
balancing redox equations and much more. Try it.
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