Physics 420

Demonstration Construction

Demo 1

Effect of CO₂ on Temperature

Materials:

2 lamps

2 lights bulbs

2 acrylic containers

2 thermometers

2 bottles

2 chopsticks

String

Vinegar

Baking Soda

Purpose:

This demonstration shows how carbon dioxide affects atmospheric temperature. We compare one system with more carbon dioxide to another system which has normal air.

Procedure:

The experiment is set up as above. The thermometers are placed hanging from a chopstick and thread down into the containers. The lamps are placed with the light bulb directly above the containers. The left side has normal air while the right side has a mixture of baking soda and vinegar. Through several tests, I found the best mixture of baking soda and vinegar is approximately 3:1. For my experiment I used 100 ml of vinegar and 30 ml of baking soda. This mixture creates carbon dioxide. The reaction that takes place has two steps:

HOAc + NaHCO₃ --> NaOAc + H2CO₃

H2CO₃ --> H2O + CO₂(gas)

Where "Ac" is an abreviation for acetate, CH₃CO₂.

Measurements are made of the temperature ever minute for half an hour and the results are graphed.

Results / Conclusion:

CO2 (°C)	Control (°C)
21.5	21.5
21.8	21.6
22	22
22.4	22.4
23	23
23.2	23.2
24	24
24.2	24.2
24.6	24.5
25	24.8
25.2	25
25.6	25.2
26	25.4
26	25.5
26.4	25.8
26.6	26
27	26
27.1	26
27.4	26.2
27.6	26.4
27.8	26.5
28	26.8
28	26.8
28.1	26.8
28.1	27
28.1	27
28.1	27.1
28.2	27.2
28.2	27.2
28.2	27.3

The temperature of the environment with more CO₂ increased faster than the environment with a normal air composition. The temperature of the CO₂ environment reached maximum of about 28.1 °C where the control reached a maximum of approximately 27.2 °C. The results of the experiment show that the environment with increased CO₂ levels reaches a higher temperature than the normal air environment. The chemical reaction that takes place to create the CO2 creates bubbles. Once the reaction stops, the bubbles stop forming and the temperature of the excess CO2 environment drops back to the same level as that of the control. This proves that an environment with more CO2 will have a higher temperature.

Demo 2

Heat Flow

Materials:

Container

Water source with constant flow

Purpose:

To visualize heat flowing into and out of the Earth’s atmosphere and the effect that global warming has on heat.

Procedure:

The container was pierced with three holes of equal size. The container was placed under a faucet with water flowing into it at a certain rate. The system was left alone until the water reached an equilibrium height. The height was noted and then a hole was blocked off. The system was once again allowed to reach a new equilibrium and the new height of the water was noted.

Results / Conclusion:

This demonstration shows the dynamic equilibrium that occurs in the Earth’s environment. The water flow represents heat flow. Once the tap is turned on, it is left alone. So the water always flows into the container at a constant rate. The water flow represents heat flow into and out of the Earth’s environment. The level of the water represents the average Earth’s temperature. Once a hole is blocked, the water level rises in the container and reaches a new equilibrium. A hole blocked is similar to greenhouse gases. The water level rises and reaches a new equilibrium higher than the original one. Therefore, average temperature has risen and eventually flow in matches flows out again.