C2H6O乙醇燃烧时的化学方程式

C2H6O乙醇燃烧时的化学方程式
一共有3个化学方程式：
C2H60 + 02 - CO2 + H2O
C6H12O6 + O2 - CO2 + H2O + heat
CO2 + H2O + light - C6H12O6 + O2
这几个有什么区别?哪个才是真正的乙醇燃烧时的化学方程式（在以乙醇
为燃烧材料,发动汽车的情况下）?
我在看国外的网站上看到的。。
原文：During ethanol fermentation, glucose is decomposed into ethanol and carbon dioxide.
C6H12O6 → 2C2H6O + 2CO2
During combustion ethanol reacts with oxygen to produce carbon dioxide, water, and heat: (other air pollutants are also produced when ethanol is burned in the atmosphere rather than in pure oxygen)
C2H6O + 3O2 → 2CO2 + 3H2O
Together, they add up to:
C6H12O6 + 6O2 → 6CO2 + 6H2O + heat
This is the reverse of the photosynthesis reaction, which shows that the three reactions completely cancel each other out, only converting light into heat without leaving any byproducts:
6CO2 + 6H2O + light → C6H12O6 + 6O2