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Science fair secrets 3: The $250 science lab

This is part of a series (copyright R Ford Denison) on the secrets of winning science fair projects. Click "science fairs" under Categories (at right) for more.

It is quite possible to do good experimental science fair projects using only everyday materials (rulers, paper cups, etc.). However, a small investment in inexpensive scientific apparatus can greatly expand the range of feasible experiments. For a fraction of the cost of a desktop computer, you can measure weight (mass), volume, temperature, acidity (pH), and light, all with sufficient accuracy to generate useful data. Unlike a computer, this equipment won't be obsolete in two years, or in twenty. These prices are old, so it might be a $275 science lab by now. On the other hand, these are all new prices; used would be cheaper. Items earlier on the list are most widely useful. Add an inexpensive microscope and you'll be about as well-equipped as Darwin. Aside from the boat, gun, greenhouse, and assistants, of course.

Compare with this much more ambitious home lab. Before spending that kind of money, I would wait and see what direction my research was going.

Item.................................................................Price

Triple beam pan balance (600 g x 0.1 g).......$ 93.00
Graduated cylinders (100 mL).................2 for 11.00
Multitester (use with sensors below)..............24.99
Mini-hook adaptors for above.............................2.59
Thermistors, for temperature (2 @ 1.99)...........3.98
Photocell assortment, for light............................1.98
Red-fluid thermometers (2 @ $6.50)................13.00
Acid/base pH indicator paper...........................13.30
Range extension set for balance (2 kg) ........24.95
Stopwatch.......................................................10.00

Safety alcohol burner......................................16.80
Ring stand (support rod)..................................14.40
3" ring for above................................................8.10
Small object clamp for above.............................8.30

Total:...........................................................$ 246.39

Sources: Edmund Scientific, Radio Shack, Fisher

An example of an experiment you could do with only the above, plus a metal or Pyrex container from the kitchen, would be a comparison of the heat output of two different alcohols.

1) Put the alcohol burner on the balance, to measure fuel use as loss of weight.
2) Put the container (with water) above the burner, on the 3" ring on the ring stand.
3) Suspend a thermometer in the water, using the small object clamp.
4) Measure the water temperature as it heats up, and graph it over time. (While you're at it, stick a thermistor in there and measure how it's resistance changes, using the multimeter; plot these data together with the thermometer temperature and you've got a calibration curve for the thermistor, for future use. An extra data graph in your lab notebook, or even in your display, never hurts!)
5) Repeat with the second fuel (ethanol vs. propanol, say). Remember to test each fuel at least twice.

The slope of the temperature vs. time curve is proportional to the heat from the burning fuel. Each 1 C increase in temperature requires one calorie of energy from the fuel for each gram of water in the container. As a second measure of heat output, measure the rate of evaporation, once water reaches boiling. Each g evaporated takes 540 calories.

I plan to use this example again in a future Science Fair Secrets entry on how a little simple math can really add up.

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