Hooked on science: How salt makes ice melt

Most of us are happy to see the salt trucks out when Old Man Winter visits, but have you ever wondered how salt melts ice? Grab a few items from around the house for an experiment that will show you why salt is important during the winter.

Materials

• Ice cube
• String
• Salt

Instructions

STEP 1: Place the string across the ice cube.

STEP 2: Sprinkle the salt on top of the ice cube and the string.

STEP 3: Several minutes later attempt to lift the ice cube by using the string.

Explanation

Water freezes at 32 degrees Fahrenheit, but when you add salt to ice the freezing point is lowered to below 32 degrees Fahrenheit. When you added salt to your ice cube, a small puddle formed around the string. The ice cube froze the small puddle which allowed you to pick up the ice cube using the string.

Jason Lindsey is a Science Outreach Educator with Hooked on Science. Check out his website "Hooked On Science" at hookedonscience.org for webcasts and experiments that might get you hooked on science. Send him your science questions at jlindsey@hookedonscience.org. More science experiments can be found at www.semissourian.com.