Wanna see a magic trick? Magicians always make their tricks look like supernatural phenomena. But scientists can do “magic” tricks with explanations that are almost as cool as the tricks themselves.
In this experiment, we’re going to magically lift a piece of ice using only string and salt. Can we do it? Let’s find out.
Can you lift an ice cube out of water with just a piece of string and salt?
- Ice cube
- Glass cup
- 6 inches of string
- Fill the cup with cold water.
- Place the ice cube on the surface of the water.
- Lay the string across the top of the ice cube
- Pour salt on top of the ice cube and the string.
- Wait 5 minutes.
- Do you think the string will be able to lift the ice cube? If so, explain why. Use this time to write down your guess, also called a hypothesis, in your notebook.
- Gently pull the string on both sides and lift upwards.
The string will lift the ice cube out of the cup.
The string alone could probably never lift an ice cube out of the cup. However, salt elevates the temperature at which water freezes, causing the surface of the ice cube touching the string to rapidly melt. The salt quickly gets diluted into the rest of the water, causing the temperature at which the water can freeze to drop back down again. This allows water to quickly refreeze near the surface of the cube, trapping the string. Now, you’ll have no problem lifting the ice cube out of the water!