Recall from the previous review page that many equations, as one proceeds through balancing process, coefficients entered previously may need to be adjusted.
Consider unbalanced equation for the combustion of ethane to give carbon dioxide and water. This example will be used to reinforce add to your bag of tricks for cases when you get right to the end and cannot write integer coefficients for the last substance.
Consider unbalanced equation for the combustion of ethane to give carbon dioxide and water. This example will be used to reinforce add to your bag of tricks for cases when you get right to the end and cannot write integer coefficients for the last substance.
C2H6(g) + O2(g) 
CO2(g) + H2O(g)
First balance carbon.
C2H6(g) + O2(g) 2CO2(g) + H2O(g)
Then balance hydrogen (it occurs in one formula in both reactants and products).
C2H6(g) + O2(g) 2CO2(g) + 3H2O(g)
Then oxygen can not be easily balanced there are 7O in products and 2O in reactants.
Strategy: Double all of the previously entered coefficients.
2C2H6(g) + O2(g) 4CO2(g) + 6H2O(g)
Then balance oxygen.
2C2H6(g) + 7O2(g) 4CO2(g) + 6H2O(g)
Note there is actually nothing wrong with fractional coefficients and indeed these will be used in some applications, but it is most common to see reactions written with coefficients that are integers. CO2(g) + H2O(g)First balance carbon.
C2H6(g) + O2(g)
2CO2(g) + H2O(g)Then balance hydrogen (it occurs in one formula in both reactants and products).
C2H6(g) + O2(g)
2CO2(g) + 3H2O(g)Then oxygen can not be easily balanced there are 7O in products and 2O in reactants.
Strategy: Double all of the previously entered coefficients.
2C2H6(g) + O2(g)
4CO2(g) + 6H2O(g)Then balance oxygen.
2C2H6(g) + 7O2(g)
4CO2(g) + 6H2O(g)