Se considera ca in amestecul initial sunt a moli C3H8 si b molei C4H10.
80 ml amestec= 0.08 l amestec => 0.08/22.4=0.0035 moli amestec=> a+b=0.0035
Din arderea a:
a moli C3H8 => 3a moli CO2
b moli C4H10 => 4b moli CO2
300 ml CO2= 0.3 l CO2=> 0.3/22.4=0.0133 moli CO2 => 3a+4b=0.0133 moli CO2
Rezolvand sistemul obtinem 0.0007 moli C3H8 adica 20% si 0.0028 moli C4H10 adica 80%.