An #8.8*g# mass of propane is completely combusted. What mass of carbon dioxide will result?
WE have the stoichiometric equation:
Which tells us unequivocally that the combustion of 1 mole of propane gives 3 moles of carbon dioxide.
And then we simply access the molar quantity of propane:
And since, per the stoichiometric equation, if
At normal pressure and temperature,
24 litres at RTP (298K) or 22.4 litres at STP (273K)
1) The balanced equation gives us the mole ratio propane:oxygen which is 1:5 - this means that every mole of propane will require 5 moles of oxygen for complete combustion.
2) However we don't have one mole of propane, we have 8.8g which, using moles =mass/molar mass, equals 8.8/44 = 0.2 moles. (RMM of propane = 12x3 + 1x8 = 44, therefore molar mass = 44g/mol).
3) Applying the mole ratio, it follows that 0.2 moles of propane will react with 0.2x5 = 1 mole of oxygen.
4) One mole of any gas (assuming ideal behaviour, which is a perfectly reasonable assumption, especially with a gas like oxygen with small and non-polar molecules) occupies 24 litres at RTP and 22.4 at STP. Presto!