Questions: Water as Solid, Liquid, and Gas

Question 1

You leave an ice cube on a plate in a warm room. After 30 minutes, the ice is gone and there is a puddle of water. What happened?

• A. The ice disappeared
• B. The ice melted -- it changed from solid water to liquid water because the room is warmer than freezing
• C. The plate absorbed the ice
• D. The ice turned directly into air

Answer: (B)

The ice melted. Ice is solid water, and when it gets warmer than 0 degrees Celsius (32 degrees Fahrenheit), it changes from solid to liquid. The warm room provided the heat needed to turn the solid ice into liquid water. Nothing was created or destroyed -- the ice just changed form.

Question 2

Ice, liquid water, and water vapor are three different substances.

• T. True
• F. False

Answer: False

They are all the same substance -- water. The difference is temperature and energy. When water is cold enough, it freezes into solid ice. When it is warmer, it is liquid. When it gets hot enough, it becomes water vapor (gas). These are three forms (states) of the same material, not three different materials.

Question 3

Name all three forms of water and give one place you might see each one in everyday life.

Model answer: Solid: ice -- you see it in ice cubes, frozen puddles, or snow. Liquid: water -- you see it coming from a faucet, in a glass, or in a rain puddle. Gas: water vapor -- you cannot see it directly, but you can see its effects when steam rises from a hot shower or pot of boiling water, and the visible mist is actually tiny liquid droplets formed by water vapor condensing.

Connecting each state of water to everyday experience makes the concept tangible. Noting that water vapor is invisible (the visible mist is condensed droplets) addresses a common point of confusion.