Fermentation sim
Yeast turns glucose into ethanol and carbon dioxide: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂.
Fermentation · covers the GCSE, IGCSE, O-Level topic
What the sim shows
Yeast turns glucose into ethanol and carbon dioxide: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. Keep the air out, and keep it warm: 30 to 40 °C is best. Colder, the yeast's enzymes work slowly; above about 45 °C they are denatured and it all but stops. The carbon dioxide bubbles through the limewater, which turns milky. So much gas passes that the limewater clears again: more CO₂ turns the white calcium carbonate into soluble calcium hydrogencarbonate. (Most of each bubble passes straight through; we take a tenth as reacting.) Fermentation stops by itself at about 15% ethanol, because the ethanol kills the yeast, even with glucose left. Open to the air, the yeast respires instead and bacteria turn the ethanol into ethanoic acid (vinegar). The slider spends its first fifth on the first hour. The rates are this desk's estimates for a school flask; the 15% and the equation are the lesson's.
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