Overview
This lecture demonstrates an experiment on fermentation using yeast and sugar, highlighting the production of carbon dioxide gas and ethanol.
What Is Fermentation?
- Fermentation is the chemical breakdown of substances by microorganisms like yeast or bacteria, producing gases and heat.
- Yeast is a type of fungus used in food processes such as bread rising.
Experiment Setup
- Materials: several bottles, sugar, yeast, balloons, funnel, measuring utensils, warm water, gloves, goggles, apron/lab coat.
- Each bottle receives 2¼ teaspoons of yeast.
- Sugar amounts: bottle 1 (none), bottle 2 (1 tsp), bottle 3 (2 tsp), bottle 4 (3 tsp).
- Add 1 cup of warm water to each bottle.
- Mix ingredients, cover with a balloon, and let sit in a warm area for 1-2 hours.
Experimental Observations & Results
- Balloons inflate over time as gas fills them.
- Bottles with more sugar cause larger balloon inflation.
- Yeast consumes sugar, producing carbon dioxide (CO₂) and ethanol as waste products.
Science Behind the Experiment
- Yeast feeds on sugars and starches, metabolizing them for energy.
- The metabolic process releases carbon dioxide gas and ethanol.
- CO₂ gas pressure inflates the balloon.
- Reaction equation: Sugar (sucrose) → Ethanol + CO₂.
Key Terms & Definitions
- Fermentation — Breakdown of substances by microorganisms, producing gas and heat.
- Yeast — A fungus used in fermentation processes; microscopic and widely used in baking.
- Carbon Dioxide (CO₂) — Gas produced during fermentation.
- Ethanol — Alcohol produced as a fermentation byproduct.
- Metabolism — Chemical process in living organisms to convert food to energy.
Action Items / Next Steps
- If replicating the experiment at home, always get parental permission before sharing photos or videos.
- Wear appropriate safety gear (gloves, goggles, apron/lab coat) during the experiment.