Introduction
Do you sometimes dump ice cubes into a drink to help keep cool on a hot summer day? Have you ever watched the ice cubes melt and wondered how you could make them melt more slowly—or even faster? In this science activity you will get to try some different, common household substances to try and answer this question: What will help a solid ice cube turn into a liquid puddle the fastest?
Background
Temperature isn't the only thing that affects how a liquid freezes—and melts. If you've ever made homemade ice cream the old-fashioned way using a hand-crank machine, you probably know that you need ice and salt to freeze the cream mixture. Similarly, if you live in a cold climate, you've probably seen the trucks that salt and sand the streets after a snowfall to prevent ice from building up on the roads. In both of these instances salt is lowering the freezing point of water, which means that the water needs to be colder to turn from liquid into ice. For the ice cream maker, the temperature of the ice–salt mixture can get much lower than if just using normal ice, and this makes it possible to freeze the ice cream mixture. For the salt spread on streets, lowering the freezing point means that ice can melt even when the outdoor temperature is below water’s freezing point. Both of these events demonstrate “freezing point depression.”
See full Article: What Makes Ice Melt Fastest? - Scientific American
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