Frosty Fun:
Can we make water
change state?
4.5B Physical Engage
Students must know…
O How to observe and record changes in the
states of matter caused by the addition or
reduction of heat.
Gather the materials:
O Soda can (per group)
O Water (per group)
O Salt (per group)
O Crushed ice (per group)
O Stir stick (per group)
O Plastic spoon (per group)
Set the scene
O Show a soda can.
O Explain to students that
they will be mixing salt
and ice inside the can
to see what happens.
Explain the set up
O Say:
O We are going to try to make water that is in the
air change state. Right now around us it is a gas
– water vapor. What other states can it turn into?
Get students thinking…
O Brainstorm some ways that studenst
have seen water change state:
O Boiling water on the stove
O Freezing water in the freezer
O Melting ice in iced tea
Identify how water has changed state.
Demonstrate the set up
1. Put 5 tablespoons of salt into
the can.
2. Add crushed ice to fill the can
half way.
3. Stir the salt and ice mixture with
the stir stick.
4. Observe what happens.
Students will observe the
changes:
O Frost will form on the
bottom half of the
can (where the salt
and ice mixture is).
O Water vapor changes
directly to solid ice.
O Ask:
O Why did we see that
happen?
Explain what happened
Frost forms because the ice and salt mixture is
very cold, and cools the can enough so that
the water vapor contacting the can freezes
without ever going through the liquid state of
water. Notice no frost forms on the upper part
of the can.