Question

2500cc of oxygen was burnt with 600cc of ethane c2h6. calculate the volume of unused oxygen and the volume of carbondioxide formed?

Answer 1

2C2H6 +7O2 ----> 4CO2 + 6H2O 

   2 vol   : 7 vol    ::    4vol   :   6 vol               [  By Gay Lussac's law ]  

2 vols of C2H6 gives 4 vols of CO2              

600cc of C2H6 gives 4/2*600 cc of CO2

600cc of C2H6 gives 1200 cc of CO2

CO2 produced = 1200cc

2 vols of C2H6 gives 6 vols of O2

600 cc of C2H6 gives 7/2*600 vols of O2

600 cc of C2H6 gives 2100 vols of O2

Unused O2 = 2500-2100

Unused O2  = 400 cc