Example: 1
Carbon monoxide burns in oxygen to give carbon dioxide, as per the equation:
Calculate the volume of oxygen required for the complete combustion of 30 litres of carbon monoxide. What is the volume of carbon dioxide produced?
Solution:

30 litres: x litres : y litres
CO : O2 CO : CO22 : 1 2 : 2
30 : x 30 : y2x = 30 x 1 2y = 30 x 2
x = 15 y= 30
Volume of oxygen = 15 litresVolume of carbon dioxide = 30 litres.
Example: 2
In the Haber's process nitrogen and hydrogen combine to form ammonia, according to the following equation:
Solution:

1 : 2 1 : 3
200 : x 200: yx = 2 x 200 y= 200 x 3
x = 400 y = 600Hence, volume of ammonia Hence, volume of hydrogen produced = 400 litres needed = 600 litres
Volume of excess hydrogen = 1000 - 600 = 400 litres.Example: 3
About 40 g of sulphur is taken in an enclosed vessel containing 22.4 litres of oxygen. The sulphur is ignited. Calculate the volume of sulphur dioxide formed, and the mass of uncombined sulphur. (1 mole of S= 32 g: molar volume = 22.4 litres)Solution:

1 : 1 32 g : 1 vol.
22.4 : x y : 22.4 litres or 1 molex = 22.4 litres y = 32 g
Volume of SO2 produced Mass of uncombined sulphur= 22.4 litres = 40 - 32 = 8 g
Example: 4
Methane burns in oxygen to form water vapour and carbon dioxide according to the equation:
Solution:

1 : 2 1 : 2 1 : 1
200 : x 200 : y 200 : zx= 2 x 200 y = 200 x 2 = 400 z = 200
x = 400 y = 400Volume of oxygen Volume of steam Volume of carbondioxide used up = 400 ml = 400 ml = 200ml
Hence, the volume of uncombined oxygen= 500 - 400
= 100 mlTotal volume of gases after combustion:
= Volume of steam + Volume of CO2 + Volume of excess or uncombined O2= 400 + 200 + 100
= 700 ml.