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

2 C2H6  + 7 O2 --->4 CO2 +6 H2O 

 ethane rqd = 2volume 
oxygen rqd = 7 volume
 therefore for 600 cc of ethane 
volume of oxygen rqd = 300 x 7 cc = 2100 cc 
volume of carbon dioxide formed will be =  4 volume = 4 x 300 cc = 1200 cc 
volume of unused oxygen left = 2500 - 2100 =400 cc

Answer 2

2C2H6 + 7O2 ------>  4CO2 + 6H2O +Δ [equation]

Given:

C2H6 used = 600cc

C2H6                     O2

  2                          7    [ratio]                         

  600                      x

x = 600 x 7 /2

x = 2100cc [used oxygen]

So unused oxygen =  2500-2100  =  400cc

Volume of CO2 produced:

C2H6                          CO2

  2                                4       [ratio]

  600                            x

  x   =  600 x 4 / 2

  x  =  1200cc

Therefore 1200cc of CO2 is produced.

Hope it helps..........................