Chlorine The Bacteria Killer

Biology, Chemistry:	Anti-Bacterial Cleaners
Grade Range:	Elementary School, Middle School
Format:	Hands-on

This is your basic yeast demonstration with an addition of bleach. This demonstration is simple to set up and easy for kids to understand, but you will want towels in case there is a spill.

Materials

• 6 Test Tubes
• Test Tube Stand
• Balloons
• Yeast
• Sugar
• Water
• Hot Plate
• 600mL Beaker
• Bleach

Safety Precautions

Please read the General Safety Precautions section of the Demonstration Safety page before performing this demonstration.

Demonstration

1. Prepare the test tubes: Put a small amount of yeast in each test tube along with some sugar in each. In three of the test tubes, fill them 1/4 of the way with bleach. Add water into each test tube, filling them about 2/3 of the way, and put a balloon on each test tube. Set them all in the beaker, fill the beaker 2/3 with water, and set it on the hot plate on a low setting.
2. As students come to visit your table and as the test tubes warm, the yeast will wake up and start to consume the sugar, releasing CO₂ and filling the balloons. Once a few balloons are noticeably filled with air, set all the test tubes in the test tube stand.
3. After explaining that there is yeast in each of the test tubes, ask students for ideas on why some of them aren't producing CO₂. Discuss and explain.

Why This Works

COMING SOON

Additional Information

• This demonstration is shown another way in the Life on Mars demonstration.