Datalogging in Science

Greenhouse effect

Overview

The green house effect is the term given to the ability of gas in the atmosphere to create an increase in temperature of the atmosphere. Carbon dioxide is one of many green house gases. This experiment will use carbon dioxide to create a green house atmosphere and simple bench lamps to act as the sun. The temperature rise inside the model worlds will be used to test the effect of a green house gas to give an increase in temperature above what would be normal for heated air.

Background
The green house effect is described as the heating of the atmosphere by compounds that absorb short wave radiation and re radiate it as longer wave heat radiation. It gained the term green house effect when scientists studied how a garden green house heated up in sunshine, they saw this effect as a simple model for how the Earth’s atmosphere was kept warm by solar radiation.

Apparatus

1. An EASYSENSE logger.

2. Three temperature sensors.

3. Three bottles of equal shape, size and volume with caps or bungs with a hole to take Temperature

4. Some Soluble aspirin / paracetamol (the Carbon dioxide source).

5. At least 2 bench lamps with equal power and type of bulbs (Tungsten filament).

Practical Advice

Soluble aspirin (Alka Seltzer) or paracetamol are used as they produce a convenient unit of carbon dioxide. Make sure they are the effervescent variety. The larger Alka Seltzer allow the tablet to be split.(Sodium bicarbonate and weak acid will produce carbon dioxide.)

A small amount of water is needed in each bottle, this is to act as control (the tablets won’t release carbon dioxide without water) and it creates a heat-absorbing atmosphere.

One litre milk containers work well, the opaque material seems to catch the heat better than transparent bottles, but make sure they have been thoroughly cleaned.

Try to ensure the temperature sensors are the same distance from the bottle walls in all cases.

Rubber bungs can make this easier to control but the caps that come with the bottle are much more convenient and easier to prepare.

Place the lights about 0.5 meter from the bottles.

Procedure

1. Place a small amount of water in each bottle (about 20 cm3), It must be same quantity in each bottle.


2. Push the temperature sensor through the cap / bung and check that when the bung /cap is in place the temperature sensor is about half way down the bottle.

3. Set up the apparatus as shown in the diagram, Switch the lights on to try to make sure the light from the lamps is even on the bottles. Switch the lights off.

4. Launch the Graph software

5. Add 1 tablet to bottle one, 3 tablets to bottle 2 and leave bottle 3 with water only.
Let the tablets fizz away, they are releasing carbon dioxide into the bottle.

6. Place the Sensors into the bottles and begin recording. Leave the lights off for a few moments to collect a baseline temperature.

7. Turn the lights on and let recording continue for approximately 10 minutes.

8. After 10 minutes, or when the temperature increase starts to level off, turn the lights off and allow the logging to continue for another 10 minutes.

9. Stop the logging and save the data.


Results and analysis

The graphs should reveal a set of temperature lines that show an increase in temperature with time
After the lights are turned out the temperature will show signs of a decrease.
Zoom in to analyze relevant areas of the graph and then answer the following questions:

Questions

Each bottle will have contained a different quantity of carbon dioxide:
bottle 1 – 1 ‘volume’,
Bottle 2 = 3 ‘volumes’
and bottle 3 ‘No volumes’.
The light should have been equal, so each bottle should have collected the same amount of heat energy from the lamps.

Examine the graphs and answer the following questions.

1. Which bottle showed the quickest rise in temperature?

2. Which bottle showed the slowest rise in temperature?

3. When the light was turned off which bottle showed the quickest drop in temperature?

4. When the light was turned off which bottle showed the Slowest drop in temperature?

5. How does the carbon dioxide affect the change in temperature in the three bottles?

6. Why did we put the same amount of water in each bottle?

7. What was the water for in the bottles?

Data Harvest Users

1. Connect the sensor to the datalogger and the logger to the computer
2. Then click the Set Up icon to the right of this message.
3. When the software opens, click the Play button.