Test the effect of a green house on temperature
Answers
Answer:
The Greenhouse effect is when greenhouses gases, such as carbon dioxide, cause some of the radiation from the sun to be trapped in the troposphere
Hypothesis:
If greenhouse gases from the candle are present in the covered beaker the temperature will rise more quickly than the beaker without greenhouse gases because the gases will reflect the heat from the lamp back into the beaker and raise the temperature.
Independent Variable: The addition of gases from the candle
Dependent Variable: The temperature of the beakers.
Controlled Variables: The beakers were exactly the same, the same thermometer, the same baggie size, and the same distance from the lamp.
Control Group: The beaker without the gases from the candle.
Experimental Group: The beaker that contains gases from the candle.
Problem:
How quickly does the warming of the atmosphere occur? What conditions cause the warming of the atmosphere?
Materials:
· Beakers
· Zip-loc baggies
· Thermometers
· Candle
· Match
· Soil
· Lamp
Procedure:
1. Fill two beakers with 100 mL of soil.
2. Carefully light the candle with the matches.
3. Cautiously drop the candle into one of the beakers with soil.
4. Allow the candle burn for two – three minutes to be sure gases get released in the beaker.
5. Blow out the candle.
6. Quickly place the thermometers in the beakers
7. Cover the beakers with zip loc baggies as quick as possible to be sure the gases from the candle don’t escape.
8. Measure the temperature of each beaker every five minutes.
Answer:
Topic
This activity aims to teach students about the thermal properties of carbon dioxide – the properties that make it a greenhouse gas. It also teaches about the effect of a green house on temperature
Description
The activity consists of a demonstration in which a data logger is used to record the changing temperature of air and of carbon dioxide in plastic bottles as they are heated using electric lamps, and then allowed to cool. If a data logger is not available, then thermometers (0° -100°C range) can be used instead and monitored by pupils. The activity allows students to compare the thermal properties of carbon dioxide with those of air, and can be extended to compare water vapour as well. The gas which absorbs the most heat (infrared radiation) is the most effective greenhouse gas as in the atmosphere it would absorb more infrared coming from the Earth’s surface.
Context
Increasing atmospheric carbon dioxide levels and associated global warming are often in the news – for example, coverage of an international environment summit (like that held in Johannesburg in 2002) or of local initiatives to cut carbon dioxide emissions (like ‘Walk to School Week’), or energy-saving initiatives in school. So, pupils are probably quite familiar with the main issues at stake in the global warming debate such as where the excess carbon dioxide in the atmosphere comes from, what might be done to reduce emissions, and that the climatic consequences for Earth could be devastating. However, it is difficult to understand quite why a colourless, odourless gas like carbon dioxide should be such a villain. It is abundant in the air, plants need it to photosynthesise and we breathe it out – how can it be so damaging to have large amounts of it in the atmosphere? This activity demonstrates the invisible, thermal properties of carbon dioxide which are what makes it into such an effective greenhouse gas and thus contributes greatly to global warming.
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Apparatus
Data logger connected to a PC
Two external temperature probes or thermometers (0°C-100°C range) if data loggers and PC are not available
Two 2-litre plastic pop bottles
Two clamp stands, bosses and clamps
Carbon dioxide eg from a Soda Stream
Two heat lamps or flexible spot lights (at least 60 W)
Plasticine™
Safety
Do not place the light bulbs too close to the plastic bottles as they will melt.
Activity and preparation
Prepare plastic pop bottles by removing the labels and drilling holes in the tops big enough to allow the temperature probes or thermometers to pass through
Set up clamp stands and heat lamps as shown in Figure 1.
Fill one of the bottles with carbon dioxide, screw the top on (with temperature probe / thermometer in place) and plug any gaps with Plasticine™.
Prepare the other bottle full of air by screwing on the top (with temperature probe / thermometer in place) and plug any gaps with Plasticine™.
Monitor the temperatures of both bottles until they are approximately the same. At this point switch on the heat lamps and start the recording.
After 20 minutes switch the heat lamps off but continue recording the temperatures for a further 20 minutes
Plot a graph of temperature against time
Explanation:
Typical results
Even over a small time period such as 20 minutes we are still able to get a difference of 4°C in temperature between the two samples, the carbon dioxide warming more and faster than the air .
It should be stressed that scientists are in general agreement that an average increase of just 2°C across the planet could have catastrophic effects on crop production and cause sea levels to increase significantly resulting in major flooding.