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Frozen Laundry Race

There are three factors at play when it comes to drying clothes outside at any time of year – heat, humidity, and time.

In winter, you have less heat, so you need to optimize the other two factors. You'll need more time, but cold winter air holds less humidity. The liquid water evaporate out of your clothes and into the atmosphere, since substances naturally go from areas of high concentration (your clothes) to low concentration (the air). If there is a wind, this process is optimized by the flow of air , carrying off the humidity produced when the water in your clothes evaporates.

If it’s dry and cold outside, you might get freeze-dried clothes. What you think is frozen might actually turn out to be mostly dry, once you brush off the ice crystals. If it is cold and dry enough, there may be no ice, as the water may sublimate directly into gaseous water vapour.

One possible introduction: students are working in Antarctica and their parents are coming to visit. All the clothes that were shoved to the outside of the tent are now frozen β€” can you clean up fast enough?

Objectives

  • Describe the processes of freezing and melting.

Materials

  • Per Class:
    10 to 15 T-shirts
    freezer

Key Questions

  • Was it easy to unwrap the T-shirt at first?
  • What had to happen before the T-shirt could be undone?
  • What change of state is happening?

What To Do

Preparation

  1. Soak t-shirts completely in water and squeeze most of the water out.
  2. Roll and twist the t-shirt up in to a ball and put them in the freezer overnight.

Instructions

  1. Put students in groups of 2 or 3.
  2. Give each group a frozen t-shirt ball.
  3. Race to untangle the t-shirt.
  4. First team to have someone wear the t-shirt wins!