Question

Write and balance the equation for the complete combustion of ethane, C2H6.

Answer 1

Combustion reaction means reaction with O₂. Complete combustion of hydrocarbons always forms two products only - CO₂ and H₂O.

First Step:

First you should set up a basic equation:

C₂H₆ + O₂ ---> CO₂ + H₂O

The next step is to balance the equation.

Second Step:

You should start balancing the carbon atoms first. Oxygen atoms should be balanced at the last step to modify the equation. This is relatively easier approach.

Balancing the carbon atoms both side of the equation produces-

C₂H₆ + O₂ ---> 2CO₂ + H₂O

Third Step:

Now we have to balance the hydrogen atoms. Balancing the H atoms both side of the equation produces-

C₂H₆ + O₂ ---> 2CO₂ + 3H₂O

This makes the total no of oxygen atoms at the right side of the equation = 7

Fourth Step:

Add (7/2) before O₂ at the left side of the equation.

C₂H₆ + (7/2)O₂ = 2CO₂ + 3H₂O

Now the equation is balanced, but we should replace the fraction number before O₂ with an integer number. For this multiply both sides of the equation with 2.

2C₂H₆ + 7O₂ = 4CO₂ + 6H₂O

This is the balanced equation for the combustion of ethane.