STEM Activity: The SuperFast SuperCool
Science is super cool — especially when ice and salt are involved. Supercool water below freezing point and then discover how to make ice on demand in this ice experiment!
- Glass, very clean
- Ice cubes (made from tap water)
- Mixing bowl, large
- Salt (1/4 cup)
- Thermometer (optional)
- Water, purified or distilled
- Fill a mixing bowl with ice.
- Pour a couple tablespoons of purified or distilled water into a clean glass.
- Nestle the glass with water into the center of the bowl of ice so that the ice is higher than the level of water in the glass. Be very careful not to spill any ice into the glass of water.
- Generously and carefully sprinkle the salt onto the ice. DO NOT get any of the salt in the glass of water.
- Wait approximately 15 minutes for the water to cool below freezing (known as supercool). Optionally, you can carefully insert a thermometer into the glass of water to confirm if it is supercooled (less than 32 degrees F).
- Place a fresh ice cube or frozen ice pack on a small plate or other dry surface.
- Carefully remove the glass of supercooled water and slowly pour the water directly onto the ice and watch it freeze instantly on the ice.
Educators: Use this activity in the classroom with these modifications!
This is easy to demonstrate in the classroom on top of any desk or table. Prepare the materials and use this activity as an energizer or fun opening exercise to warm up your students’ minds for further investigation and discovery.
What are we learning?
Purified water can be chilled below freezing temperature and still remain in liquid form. This is possible because ice crystals need surfaces to grow upon. With purified water, however, there are not enough impurities in the liquid for ice crystals to form. When purified water is supercooled and then carefully poured onto a fresh ice cube or frozen ice pack, the cube or pack serves as the surface upon which the ice crystals are able to form. Try making ice on demand with supercooled water!