Picking Up Ice Cubes!

Key Concepts

Materials: 
3-5    Ice Cubes
3-5*     12 inch long string (yarn works well)
Table Salt
Table

Note*: You should have as many strings as ice cubes.

Activity Directions:
  1. Lay your ice cubes in a single-file row, so that all ice cubes are the same distance away from the edge of the table closest to you.
  2. With the left-most ice cube, lightly place the end of one string on top of the ice cube. 
  3. Lay the remainder of the string straight out on the table away from you.
  4. Repeat steps 2 and 3 for the rest of the ice cubes.
  5. Then, sprinkle a pinch of salt on top of each ice cube. 
  6. Let the ice cubes sit for about 60 seconds. 
  7. Try to pick up the ice cubes by picking up the string!
  8. Notice that the ice cubes have been “glued” onto the string. 
  9. If you aren’t able to pick up the ice cubes, wait another minute and try again!

Discussion Questions & Science Explanations:
  1. How do particles in a solid behave, in terms of their movement and spacing? How about liquids and gases?
    1. Particles in a solid are barely moving, just vibrating, and are pretty close together. 
    2. Particles in a liquid are farther apart and move faster than particles in a solid, and gas particles are even more spread out and move even faster than particles in a liquid or solid. 
    3. Gas particles have the most energy, followed by liquid particles which have less energy, followed by solid particles which have even less energy.
  2. Have you ever seen somebody sprinkle salt on the road on an icy winter day? Do you know why they do that?
    1. Salt lowers the melting point of the ice. 
    2. Water freezes at 32 degrees Fahrenheit but saltwater freezes at 28.4 degrees Fahrenheit. 
    3. This means that at about 30 degrees Fahrenheit, pure water will be ice, but saltwater will be liquid, even though both are the same temperature. 
  3. How did the ice cube attach itself to the string?
    1. When salt is first sprinkled on the ice, a thin layer of water on top very top of the ice melts. Remember that salt lowers water’s freezing point, so the water right on top that’s in contact with the salt melts and doesn’t immediately freeze. 
    2. However, the ice around the water gradually cools that layer of water so that it eventually refreezes. This time, the string is frozen along with that top layer of water, joining it to the ice cube.
  4. Was this a chemical reaction? And if so, why?
    1. A chemical reaction occurs when the molecular bonds of a substance change.
    2. Changing the physical properties of a substance, such as state of matter, isn’t a chemical reaction because the substance is still the same. Some common examples of each include: burning wood (chemical), cooking an egg (chemical), iron rusting (chemical), ice melting (physical), cutting paper(physical), mixing play-doh (physical). 
    3. Transforming water into ice or ice into water is not a chemical reaction, it’s actually physical. Liquid water simply decreases in temperature to become solid ice. Solid ice simply increases in temperature to become liquid water. 

Additional Experimentation:
  1. See if you can the ice cubes and strings to each other to form one longer string!
  2. Instead of table salt, does using sugar work as well?

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Suggested Video: https://www.youtube.com/watch?v=0nEJ_FN46NQ&ab_channel=MyToyVillage

​Published 9.19.2020

Author: Alex Zhang