How Salt Prevents Ice From Forming on Sidewalks

SciShow Kids

In this engaging science demonstration, the host Anthony and his robot mouse companion Squeaks explore why we put salt on sidewalks during winter. Through a simple comparative experiment using two cups of water—one with salt and one without—placed in a freezer, the video visually demonstrates how salt affects the freezing process of water. The experiment clearly shows that while fresh water freezes into solid ice at standard temperatures, saltwater remains liquid. The video introduces key chemistry and physics concepts including states of matter (solids and liquids), freezing points, and freezing point depression. It explains that water normally freezes at 0°C (32°F), but adding salt lowers this temperature threshold, requiring much colder conditions for ice to form. This scientific principle is then directly applied to the real-world scenario of keeping sidewalks safe for walking. Finally, the video encourages critical thinking about the environmental impact of using salt, noting how runoff can harm local waterways. This leads to an open-ended inquiry prompt where students are encouraged to design their own experiments to test eco-friendly alternatives like sand, sugar, or rocks, making it an excellent springboard for classroom hands-on learning.