Hooked on Science: How salt melts ice

Using a few materials from around the house you can discover the science behind how salt "melts" ice.

Materials

* Thermometer

* Salt

* Ice

* Transparent glass

Instructions

STEP 1: Place the thermometer inside the transparent glass. Fill the transparent glass half of the way with ice.

STEP 2: Record the temperature of the ice.

STEP 3: Pour some of the salt on the ice and record the temperature of the ice.

Explanation

The temperature significantly drops after you add the salt to the ice. The salt lowers the temperature at which water freezes. A 10 percent salt solution freezes at 20 F (-6 C), and a 20 percent solution freezes at 2 F (-16 C).

Jason Lindsey is a science outreach educator with Hooked on Science. Check out his website www.hookedonscience.org for webcasts and experiments.