Creating Cold

As you saw in the "Clues" section, refrigerators use a fairly complex mechanism to produce cold. There is a much simpler way to do it though, with a chemical reaction.
BE CAREFUL! Epsom salts (or magnesium sulfate) can be a dangerous compound. Make sure an adult helps you with this experiment. Handle the Epsom salts with care, and put them away safely when you are done.
 
 


Materials:

  • A thermometer
  • A tablespoonful of Epsom salts (magnesium sulfate)
  • Water at room temperature
  • A spoon
  • A medium-sized jar
  • Pencil and paper
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Touch the jar to feel the temperature of the water  

   Fill the glass with water from the tap. The water should be at room temperature. Not too hot and not too cold.

Place the thermometer in the water. Touch the jar with your hands so you can feel the water temperature while the thermometer records it.

 

Note the temperature shown on the thermometer, then put it back into the water.

 

   Pour the Epsom salts into the water, and stir with the spoon.

Do you notice a change? After a few minutes, take out the thermometer and note the new temperature.

  Pour the saltpeter into the water and stir

 

   You should have noticed a drop in temperature from your first measurement. When the Epsom salts are mixed into the water, a chemical reaction takes place. In the warm water, the Epsom salts split up into magnesium particles and sulfate particles. This reaction consumes more heat than it produces. That's why the water becomes cooler.

 

 

   Epsom salts are also used to offer pain relief from injuries like twisted ankles.

   Compounds like saltpeter are used to offer relief from sprains

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