Alcoholic and Acetic Fermentation – Esterification
Integrated ScienceChemical ReactionsAges 14–15Virtual lab
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Chemical Reactions
A fermentation vessel holds a glucose solution: switch on the yeast and CO₂ bubbles rise as the ethanol level climbs day by day. The simulation calculates the ethanol formed from C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ and converts it to alcohol content as ethanol volume divided by solution volume times 100. Move on to the acetic fermentation stage to oxidize ethanol into acetic acid and watch the vinegar concentration, or to the esterification stage to heat the acid with the alcohol using concentrated H₂SO₄ to form a fragrant ester. Drag the temperature to see the yeast work best around 30 °C and die above 40 °C.
Lesson: Ethanol, Acetic Acid and Esterification
What it shows
Yeast ferments glucose anaerobically: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂, so 180 g of glucose can give at most 92 g of ethanol. The model converts ethanol mass to volume with its density, 0.789 g/mL, and expresses alcohol content as ethanol volume per 100 volumes of solution. Yeast activity peaks near 30 °C and stops above 40 °C or once alcohol content reaches about 14°. Two later stages follow: acetic acid bacteria oxidize ethanol to acetic acid, and esterification of acetic acid with ethanol, catalyzed by concentrated H₂SO₄, reaches equilibrium at about 67% yield.
How to use
Start with the Alcoholic fermentation stage and watch sugar remaining fall and alcohol content rise on the chart as CO₂ bubbles escape. Set the Temperature slider to about 15 °C, 30 °C and 45 °C, pressing New Batch each time, to compare yeast activity. Move the Sugar slider to test whether more glucose always gives more ethanol. Press Next Stage for acetic fermentation and then esterification, and read the masses in the equation line.
Parameters you can change
- Stage Alcoholic fermentation: glucose → ethanol + CO₂, Acetic fermentation: ethanol + O₂ → acetic acid, Esterification: acid + alcohol ⇌ ester + water
- Initial glucose concentration 50–300 g/L
- Incubation temperature 10–45 °C
- Solution volume 0.5–5 L
- Simulation speed 0.2–2 days/s
Questions to explore
- Why is almost no ethanol produced when the mixture is kept at 45 °C?
- What mass of ethanol forms when 180 g of glucose is fermented completely?
- Why does the esterification yield level off at about 67% even after long heating?
