Question

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

Answer 1

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