Students use changes of state to create chilly architecture and some slippery slopes!

Salt lowers the freezing point of water. As it dissolves, the ice melts around each grain of salt. As a result, the ice is unevenly eaten away, forming a pitted, non-skid surface. This is why salt is used to melt ice on roads and walkways.

The salty water also re-freezes on the surface of the ice cubes, joining them together. This happens because the insides of the ice cubes are much colder than the freezing point of water. They are cold enough to draw heat out of the newly melted water and it re-freezes.

### Objectives

• Investigate the interactions of liquids and solids.

• Investigate changes of state.

### Materials

• Per Student or Group:
4-5 ice cubes
salt in a salt shaker
plate or tray to work on (not paper!)

### Key Questions

• Why do the ice cubes stop slipping off when you add salt?

### What To Do

1. Try to stack ice cubes into a tower.
2. Try again—but this time let the ice cubes sit out on a plate for 2–3 minutes. Then sprinkle lots of salt on the top of each cube before putting the next one on top of it.

### Extensions

• Put a piece of string on an ice cube, then sprinkle it with salt. Wait a few moments, then lift the string. The water should melt then re-freeze, sticking the string to the ice cube.

Survivors

Artist: Jeff Kulak

Jeff is a senior graphic designer at Science World. His illustration work has been published in the Walrus, The National Post, Reader’s Digest and Chickadee Magazine. He loves to make music, ride bikes, and spend time in the forest.

Egg BB

Artist: Jeff Kulak

Jeff is a senior graphic designer at Science World. His illustration work has been published in the Walrus, The National Post, Reader’s Digest and Chickadee Magazine. He loves to make music, ride bikes, and spend time in the forest.

Comet Crisp

Artist: Jeff Kulak

Jeff is a senior graphic designer at Science World. His illustration work has been published in the Walrus, The National Post, Reader’s Digest and Chickadee Magazine. He loves to make music, ride bikes, and spend time in the forest.

T-Rex and Baby

Artist: Michelle Yong

Michelle is a designer with a focus on creating joyful digital experiences! She enjoys exploring the potential forms that an idea can express itself in and helping then take shape.

Buddy the T-Rex

Artist: Michelle Yong

Michelle is a designer with a focus on creating joyful digital experiences! She enjoys exploring the potential forms that an idea can express itself in and helping then take shape.

Geodessy

Artist: Michelle Yong

Michelle is a designer with a focus on creating joyful digital experiences! She enjoys exploring the potential forms that an idea can express itself in and helping then take shape.

Science Buddies

Artist: Ty Dale

From Canada, Ty was born in Vancouver, British Columbia in 1993. From his chaotic workspace he draws in several different illustrative styles with thick outlines, bold colours and quirky-child like drawings. Ty distils the world around him into its basic geometry, prompting us to look at the mundane in a different way.

Western Dinosaur

Artist: Ty Dale

From Canada, Ty was born in Vancouver, British Columbia in 1993. From his chaotic workspace he draws in several different illustrative styles with thick outlines, bold colours and quirky-child like drawings. Ty distils the world around him into its basic geometry, prompting us to look at the mundane in a different way.