IGCSE Organic Chemistry Practice Test

Fermentation uses enzymes from yeast to convert sugars into ethanol in the absence of air. In this process, glucose is broken down through glycolysis and then further converted to ethanol and carbon dioxide, allowing energy to be released under anaerobic conditions. The overall equation is C6H12O6 → 2 C2H5OH + 2 CO2. This method is characteristic of brewing and many biofuel/bioprocess contexts, where renewable sugars are fermented rather than using hydrocarbon feedstocks. It contrasts with methods like hydrating ethene to make ethanol or dehydrating ethanol to make ethene, which are chemical syntheses that don’t involve living organisms.