Try This at Home: Insulated Ice Cream
The Second Law of Thermodynamics states that heat energy moves from warm to cold. An insulator is a material that does not allow heat energy to move through it.
What You Need
- 3 egg whites (or equivalent volume of pasteurized egg white product)
- 1 ml (¼ teaspoon) cream of tartar
- 125 ml (½ cup) sugar
- 1 slice of sheet/pound cake or 1 large firm brownie
- 1 scoop very frozen ice cream
- an oven
- a medium-sized bowl
- an electric mixer
- a cookie sheet or baking pan
- a spatula
- a plate
What To Do
1. Make sure you have an adult with you to supervise this experiment.
2. Preheat the oven to 230-260 degrees Celsius (450-500 degrees Fahrenheit).
3. Place the egg whites and the cream of tartar in the bowl. Beat them with the electric mixer for 5 minutes. Make sure the egg whites are stiff by lifting up the mixer to see if there are peaks that stay standing up.
4. Turn the mixer back on and keep beating. Slowly add the sugar, a little bit at a time. The egg whites should still be stiff, and they should also look shiny.
5. Put the slice of cake on the cookie sheet. Place a scoop of ice cream on top of the cake, making sure it doesn’t go over the edge and onto the pan.
6. Use the spatula to cover the cake and ice cream with the egg white mixture. Make sure to completely cover the entire dessert with a thick layer – you should not be able to see cake or ice cream anywhere.
7. Make a hypothesis? Do you think the ice cream will melt when you put it in the hot oven?
8. Place the sheet into the oven carefully. Let it cook for up to five minutes, until the egg white mixture looks golden brown.
9. Remove the dessert from the oven, and carefully transfer it to the plate. Eat it immediately. Was your hypothesis correct? Is the ice cream completely melted? Why or why not?
10. Clean up. Wash all dishes thoroughly.
When you whipped the egg whites, you made lots of tiny air bubbles that were trapped by the egg whites. Air is a really good insulator – insulation prevents heat energy from moving from one place to another. Even though the oven was really hot, that heat energy couldn’t get past the air bubbles to the ice cream, so it didn’t melt! The cake also helped to insulate the ice cream. Scientists in Antarctica also use air trapped inside their down jackets as an insulator, but instead of keeping heat away from their bodies, they use insulation to trap heat near their bodies so they can stay warm.
People in Antarctica need to eat a lot more calories than usual to keep up their energy in the cold weather – they may eat the caloric equivalent of 22 Snickers bars in just one day!