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What volume of oxygen gas ($O_2$) measured at $0^\circ C$ and 1 atm, is needed to burn completely one litre of propane gas ($C_3H_8$) measured under the same conditions ?
A
5 L
B
10 L
C
7 L
D
6 L
Detailed Solution
Balanced equation for the combustion of propane: $C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O$
Volume ratio of the gases: 1 : 5 : 3 : 4
At the same temperature and pressure, equal volumes of gases contain equal numbers of moles (Avogadro's law), so mole ratios are also volume ratios.
1 volume of propane requires 5 volumes of $O_2$.
So 1 litre of propane requires 5 litres of $O_2$ to burn completely.
Volume ratio of the gases: 1 : 5 : 3 : 4
At the same temperature and pressure, equal volumes of gases contain equal numbers of moles (Avogadro's law), so mole ratios are also volume ratios.
1 volume of propane requires 5 volumes of $O_2$.
So 1 litre of propane requires 5 litres of $O_2$ to burn completely.