Calculate the volume of oxygen required to burn 12.00 l of ethane gas, c2h6, to produce carbon dioxide and water, if the volumes of c2h6 and o2 are measured under the same conditions of temperature and pressure

The  volume of   oxygen required  to  burn  12.00 L  ethane is calculated  as  follows

find the moles  of C2H6  used

At  STP  1 mole  is  always =  22.4 L, what about  12.00 L

= ( 12.00L  x 1 moles)  22.4 L = 0.536  moles

write the   reacting equation

2C2H6+  7O2 = 4CO2  + 6H2O
by  use  of mole  ratio  between  C2H6 :O2   which is 2:7  the  moles  of O2 

= 0.536  x7/2=  1.876  moles

again  at  STP  1mole =  22.4 L  what  about 1.876 moles

=    22.4 L x 1.876  moles/ 1 mole =  42.02 L

Where is the graph ?