Ethene undergoes incomplete combustion to form carbon dioxide, carbon monoxide and water vapour. If the ratio of carbon dioxide to carbon monoxide formed is 9:1 when x cm^3 of ethene is burnt, what is the volume of oxygen gas consumed in the reaction?

1 Answer
May 29, 2017

Ethene undergoes incomplete combustion to form carbon dioxide, carbon monoxide and water vapour. The balanced equation of this incomplete combustion reaction is as follows.

#C_2H_4(g)+5/2O_2(g)->CO_2(g)+CO(g)+2H_2O(g)#

But as per question the ratio of volumes of #CO_2(g):CO(g)# produced is #9:1#. So this also represents the mole ratio of
#CO_2(g):CO(g)# produced.

Hence adjusting this ratio balanced equation may be written as follows
#10C_2H_4(g)+39/2O_2(g)->9CO_2(g)+CO(g)+20H_2O(g)#

Here we see #10cm^3# #C_2H_4(g)# will require #39/2=19.5cm^3"" ""O_2(g)#

So to burn #xcm^3# ethene the required volume of oxygen will be #19.5/10xx xcm^3=1.95xcm^3#