标准状况下氧气28L=28/22.4=1.25mol=40g
设烷烃分子式为CxHy,则
CxHy+(x+y/4)O2——xCO2+y/2H2O 且y=2x+2
12x+y 32(x+y/4)
11g 40g
解得x=3,y=8
于是烷烃分子式为C3H8