This page was intended for teachers of sciences who seek to illustrate the experimental method to their High School students on an easy way. If you’re a teacher, you can use it as you wish. The experiment was designed by Nasif Nahle, biologist. If you have any question, please E-mail us to bioscience@biocab.org. Thanks by your preference!

EXPERIMENTAL DESIGN ON SPECIFIC HEAT FOR HIGH SCHOOL STUDENTS.

Determining the storage of heat by water, sand and air correspondingly.

You will need the following materials:

1. Small electrical stoves with thermostat.
2. Heat-resistant metallic vessels for volumes of 1.06 quarts with drilled lids (the lids will have two holes, one to introduce the thermometer’s probe and another like an escape valve for steam and warmed-up gases).
3. Digital Probe Thermometers with Timers.
4. Distilled water.
5. Air.
6. Sand (for example silica)
7. Security gloves.
8. Security Eyeglasses.
9. Lab Coat.

Assignments for each team:

Note: The teams that will experiment with air will have to find the volume of the vessel occupied by the air that exceeds to 1.06 quarts (1.06 quarts = 1.0 L). You can persuade them on discovering the solution or you can give it to them: They have to fill a vessel up to the edge with water. Then, they have to extract the exceeding water with a pipette to reduce the volume of water down to 1.06 quarts and transfer the extracted volume of water to a testing tube to measure that volume of exceeding water with relative exactitude. Finally, they have to subtract mathematically the exceeding volume from the air contained in the vessel to add it in the formula that the team G will use to find the Specific heat of each substance.

The teams can maintain the oven at a stable temperature and take the time the substance takes to increase its temperature in 1°C. Another option is to maintain a stable temperature of the oven and let the substance to heat up by five, ten... minutes, and observe the change of the temperature of that substance in a given time (this procedure is most recommended).

Team A will estimate the time that takes a volume of water equal to 1.06 quarts to rise its temperature by 1°C.

Team B will estimate the time that takes a volume of air equal to 1.06 quarts to rise its temperature by 1°C.

Team C will estimate the time that takes a volume of sand equal to 1.06 quarts to rise its temperature by 1°C.

Team D will estimate the time that takes the heated water to return to its initial temperature.

Team E will estimate the time that takes the heated air to return to its initial temperature.

Team F will estimate the time that takes the heated sand to return to its initial temperature.

Team G will recollect the data gathered by all its colleagues and will apply the mathematical procedure to get a conclusion.

The team G will apply the next formula to find the exchange of heat in each experiment made by their colleagues:

Change of Temperature = Change of heat in calories / Specific heat of the substance X the weight of the substance in kilograms.

To find the weight of air they must to make a conversion. You can tell them that 1 cubic meter of air weighs 1.23 Kg at one atmosphere and 27°C. If you wish, tell them that one cubic meter of air is equal to 1000 L.

QUESTIONNAIRE TO BE FILLED BY ALL TEAMS:

1. What is the specific heat for each substance?

2. What substance took less time in warming up?

3. What substance took less time to cool off?

4. How long took the water to elevate its temperature in 1°C?

5. How long took the air to rise its temperature in 1°C?

6. How long took the sand to rise its temperature in 1°C?

7. Which substance stores heat for longer periods?

8. What substance is more efficient to store heat (for longer periods)?

9. Which substance stores heat for shorter periods?

10. If you do not change the temperature of the oven, but maintain it at the room temperature, would the temperature of the substance under experimentation be increased?

11. What would happen to the temperature of the studied substance if you change the temperature of the oven up to 200°C?

12. And if you change the temperature of the oven down to 0°C?

13. How do you explain your results?

14. Does the air used in your experiment contain carbon dioxide? How much in ppmv? (Note: the ppmv is the same for small volumes than for huge volumes; what vary are the volumetric units).

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EXPERIMENTAL DESIGN ON SPECIFIC HEAT

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