Amy Sass

Bottle Fountain with Changing Color Effect

Science Concept: A variety of indicators will change when exposed to oxygen in the air that surrounds us.

Materials:

1. Flask with stopper

2. 20 g of Potassium hydroxide dissolved in 1 L of water

3. 10 g glucose

4. 1/8 tsp. or less indophenol

5. 4-5 drops of resazurin

6. 2 - two liter bottles

7. Special 2 hole 2 tube connector for the bottles

Directions:

1. Dissolve 20 grams of potassium hydroxide in 1 liter of water.

2. Measure 250 mL of the KOH solution and pour it into a flask.

3. Add 10 grams of glucose, 1/8 tsp. of indophenol and 4-5 drops of resazurin. Pour solution into one of the 2 liter bottles. Put the bottle fountain contraption together.

4. Wait until solution is colorless.

5. When ready, turn the bottle over to turn pink.

6. Turn the bottle again to turn purple.

7. Turn the bottle one more time to turn blue.

8. Set the bottle aside for a few minutes.

9. The solution will turn pink and then it will eventually turn clear.

Introduction:

Boys and girls, how many of you have ever been to Buckingham Fountain, in downtown Chicago. Well, I went there this summer with my mom and dad. We had so much fun. I loved the colors in the fountain. I did not want to leave to go home. My mom told me that I could go home and make my own fountain. I was so excited, so today I brought in my own magical fountain. Raise your hands if you want to see it.

Explanation:

The explanation for the bottle:

Both of the bottles are trying to equalize the pressure, or in other words, they are trying to reach an equilibrium of air pressure. They both want the same amount of air pressure in their bottles. So when turned over, there is a plastic connection that attaches the bottles. This allows the bottom bottle to release air through one tube into the upper bottle. While this is happening, the top bottle is releasing water through the other tube into the bottom bottle. Since the water takes up space, the air goes into the top bottle because the water is taking up the space that the air occupied in the bottom bottle.

Now the question: Why does the water squirt against the top bottle?

In the base of the tubes there are several small holes. They are there because as air rushes by (and creates a vacuum or lowers pressure on the inside of the tube), and as a result water is drawn up the tube which then causes it to spray out of the top of the tube and creates the fountain effect. This is how the fountain works.

The explanation for the color change:

This experiment demonstrates that indicators are affected by oxidation-reduction. There are two indicators (resazurin and indophenol) which turn colors depending on the amount of oxygen that it is exposed to. When there is less oxygen, the solution will be colorless. When there is a significant amount of oxygen the indicators will react with it. and change colors. When the bottles are turned, the oxygen in the air above the solution is dissolved and reacts with the indicator. When the solution is left to sit the oxygen is gradually used up by the glucose, and the solution then returns to its original colorless state. This demonstration may be repeated up to 2 hours.

Safety Precautions:

Waste Disposal:

Reference: Unknown