Kids don’t have to live in a cold climate to be fascinated with ice. In fact, the hot days of summer make most of us crave ice! In the following science experiments, kids can watch ice molecules interact with water molecules, try their hand as insulating an ice cube, and learn how salt works together with ice as homeschool students lift an ice cube with a piece of string and then make ice cream.
Density Science Experiment
Water molecules, in liquid form, move around hitching and unhitching themselves to other water molecules. As the molecules lose heat, their movements slow and they lose the ability to unhitch themselves from other molecules. These loose bonds form lattice patterns with space between the molecules. This spacing is the reason ice is less dense than water and can float.
Freeze food-color tinted water in a small paper cup. Remove the colored ice from the cup and place it in a large glass of warm water. As the ice melts, watch the resulting colored water. What happens as it gets warmer?
Related Post: Convection Current Experiment
Make an Icebox Science Experiment
Before electricity, people harvested ice in the winter from frozen lakes and then stored it in icehouses for use in refrigeration during the rest of the year. The key to a good icehouse is proper insulation. The insulation needed to be dense enough to prevent warm air from reaching the ice cube.
When warm air comes in contact with slower-moving ice molecules, energy is transferred from the air to the ice. When the water molecules move faster, the ice melts.
In this experiment, kids can make their own icehouse and experiment with different types of insulating materials. Grab these supplies:
- 4 or 5 pint-sized cardboard milk cartons
- various materials for insulation, such as straw, hay, grass, cotton, dirt, sand, dried beans, etc.
Pack all but one milk carton with an insulating material using one type of material in each carton. Place an ice cube in the middle of the material. Then, close the carton.
In the remaining carton, place an ice cube without any insulation. Set all the cartons near a heater or put them outside if it is warm. After fifteen or twenty minutes, compare the sizes of all the ice cubes. Which material made the best insulation?
Salt And Ice Experiment
For this experiment, you are going to need a glass of water, ice, a string, and salt. Fill your glass 3/4 with water. Add a few ice cubes to the glass of water. Next, lay a piece of string on the ice cubes and sprinkle salt over the string.
Wait about a minute or so and then lift the string out of the water. When you lift the string, an ice cube should come with it! How did the ice get attached to the string?
Salt lowers the freezing point of water below 32 degrees. This causes the ice around the string to melt. This water refroze onto the string when it was cooled by the surrounding molecules.
We, also, use this principle of lowering the freezing point of water when we make ice cream.
Related post: Salt And Ice Experiment
Making Ice Cream Experiment
The ingredients in ice cream do not freeze at 32 degrees F like water. They need to be colder. If we are making homemade ice cream and are using ice to cool the ingredients, how do we lower the temperature of ice? Add salt!
As demonstrated in the experiment above, salt lowers the freezing/melting point of water. Adding salt to an ice-water mix can lower the temperature 8-10 degrees F. We can use an ice-water-salt mix to get the temperature of the ingredients enough to make ice cream.
To try this out, you will need these supplies:
- two sandwich-size Ziploc bags
- two cups of ice
- 8 tablespoons of kosher salt
- 1/2 cup of milk
- one tablespoon of sugar
- ¼ tablespoon vanilla
In one bag, add the milk, sugar, and vanilla. Squeeze out as much air as possible and then seal the bag. Add one cup of ice and four tablespoons of salt into the other bag. Place the sealed ingredient bag inside the ice bag. Add the remaining ice and salt.
Seal the bag and shake for ten minutes. Look to see if the ice cream is done. If it isn’t, shake for a couple more minutes. Grab a spoon and enjoy!
Try this again, but don’t add salt to the ice. What happened?
Add these activities to lesson plans for ice, water density, molecules, or winter. Younger children will also enjoy doing these activities (especially making ice cream), even if they are too young for the concept of molecules.