Boiling water without a heat source
Preparing food is a very popular activity in care communities. Surprise your residents with this experiment to make water boil AFTER leaving the heat source! Materials: 1 cup of water, microwave, 1 glass measuring cup, measuring spoons and a 1/2 teaspoon of sugar. Process: Fill the glass measuring cup with 1 cup of water and place in a microwave for 2 minutes and 30 seconds on high. Remove the cup, place on a safe surface for residents to observe and add the sugar.
Result: When the sugar is added, boiling bubbles will appear in the bowl. This happens because when you boil water in a microwave, the entire container, water and bowl, are heated. Boiling water molecules in the center escape, but there are other molecules located on the edges due to uneven heating by the microwave. Thus when you add the sugar they create a disturbance in the water, form water vapor and thus boiling bubbles.
Second experiment - ice it up!
Materials: Glass measuring cup, one inch of water, ice cubes.
Process: Place one inch of water in the cup, fill the rest of the cup with ice cubes, microwave for 2 minutes.
Result: The water will boil, but the ice will not melt. This happens because the liquid water molecules are free to move - thus boil - but the frozen water molecules are not free to move. In order to melt the ice, you would need enough hot water to melt the ice before the cubes will boil.
Lunchtime mystery solved - why does the microwave pulse when set on defrost?
Answer - The microwave defrost setting uses a series of microwave pulse followed by no microwave action so the heat from liquid molecules transfers to the frozen molecules during the no-pulse periods.