Grab your coat and your hat because it’s cold outside! Winter is here with a shiver, preparing for the snow and ice to arrive. When it does, you’ll likely see work trucks covering the roads with a mixture of sand and salt. Why? With this experiment, you can easily test what substances melt ice faster.
- Ice Cubes
- 4 bowls
- ½ teaspoon measuring spoon
- Paper and pen/pencil
- Place 3 ice cubes in each bowl.
- Next, sprinkle ½ teaspoon of salt over the ice cubes in bowl #1. Sprinkle ½ teaspoon of sugar over the ice cubes in bowl #2. Sprinkle ½ teaspoon sand over ice cubes in bowl #3. Do not put anything on the ice cubes in bowl #4 – this will act as your control.
- Move the bowls to an empty shelf in the refrigerator. Do not stack the bowls. Close the refrigerator and set a timer for one hour.
- Make a note of your starting time. Record your observations when you check on the bowls. Are any of them melting yet?
- Check back in another hour and record your observations. When one of the bowls is at least half melted, remove all of the bowls. Record the time.
- How long did it take to melt the ice in one of the bowls? This time can change depending on how cold your refrigerator is.
- If you want to expand the experiment, measure the amount of liquid in each bowl and compare.
That’s Cool! What’s going on?
Salt acts to lower the freezing point of water and changes the phase of water from solid to liquid. In the case of winter weather, treated ice can melt even though the weather is below the normal freezing point of water. This is an example of freezing point depression.
Other substances can affect the rate at which ice melts, which you can test in the experiment. Did salt work the best? Which bowl took the longest to melt? What other substances can you think of that would melt ice?