Fermentation is a chemical process. The difference between chemical and physical processes is actually quite simple. A physical change would just be one substance changing from 1 physical state to another, like freezing water to obtain ice and boiling it to make steam.
A chemical change, on the other hand, involves the chemical structure of the substance involved to change. When grapes are fermented, the sugar in them is converted to alcohol. The following equation is a good generic process for fermentation:
yeast
C6H12O6 ------> C2H5OH + CO2
yeast
glucose ------> alcohol + carbon dioxide
So, you can clearly see from this equation how the sugar (C6H12O6) is chemically changed to alcohol (C2H5OH).
A chemical change, on the other hand, involves the chemical structure of the substance involved to change. When grapes are fermented, the sugar in them is converted to alcohol. The following equation is a good generic process for fermentation:
yeast
C6H12O6 ------> C2H5OH + CO2
yeast
glucose ------> alcohol + carbon dioxide
So, you can clearly see from this equation how the sugar (C6H12O6) is chemically changed to alcohol (C2H5OH).
