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States of Matter in Water

Show state changes from solid to liquid to gas and back to liquid, with water. Measure (and graph) the temperature of the water in each state.
Science content (2016 curriculum): 
Chemistry: States of Matter, Properties of Materials (K-7)
Chemistry: Atoms, Molecules (3-7)
Chemistry: Physical Changes, Solutions, Mixtures and Separating (2, 4, 5, 6)
Science topic (2005 curriculum connection): 
Earth and Space Science: Air, Water and Soil (grade 2)
Physical Science: Properties of Matter (grade 2)
Physical Science: Chemistry (grade 7)
  • Bag of ice cubes
  • Electric kettle, preferably with transparent sides so that the water can be seen boiling inside
  • Glass lid to hold over the kettle. Alternatively, a glass bowl that can fit over a cup of hot water)
  • Thermometers
  • Coffee cups to contain hot water
  • Styrofoam cups to hold ice
  • Tongs to hold thermometer over kettle

States of matter in water demonstration
1. Here is an ice cube for each of you. Is it solid, liquid or gas? Why? Fixed size, fixed shape.
What is happening to it? Why? (It is changing to a liquid because it is getting warm in your hand. The molecules are moving apart). What’s the name for a solid changing into a liquid? Melting.
2. Now we start with liquid water. How can we make it turn into a gas? Warm it up even more - give it more energy. (Use a see-through kettle or a hot plate).
What is happening to the liquid? (Bubbles of gas are forming in it. It has enough energy to heat it up enough to turn to gas). What’s the name for a liquid turning into a gas? Evaporation.
3. How can we make the gas turn back into a liquid?
Cool it down. Put a glass lid/bowl over steam escaping from hot water - see droplets of water forming inside the glass. Why do the drops form on the glass? Because it is cooler, and they lose enough energy to move more slowly and become water again. What’s the name for a gas turning into a liquid? Condensation.
4. How can we make the liquid turn back into a solid?
Cool it down even further. Make frost on the outside of a can: (set up at the start of the lesson - it takes 15 mins to form).

Measure the temperature of water in each state
1. Measure the temperature of ice:
Half fill a styrofoam cup with ice cubes, then immerse a thermometer in it. Read the temperature once it has stabilized (maybe a few minutes). If the thermometers are properly immersed in the ice they should read 0°C or below. Students can add their temperature reading to a graph on the board. Explain that ice forms at 0°C and remains solid at any temperature below that.
2. Measure the temperature of liquid water:
Pour water into the cups by mixing boiling and cold water to vary the warmth of the water in each cup. Ask students to measure the temperature of their water, and add it to a graph on the board. All measurements should read between 0°C (the melting point of water) and 100°C (the boiling point of water).
3. Measure the temperature of liquid water boiling:
This should be a demonstration. Using heat proof tongs, dip a thermometer into the water as it comes to the boil. Ask one student to read out the temperature as it rises to 100°C (the boiling point of water). If the thermometer can be held in while it continues to boil it may rise above 100°C, as more and more bubbles of gas form within the water.

Grades tested: 
Gr 1
Gr 2
Gr 3
Gr 4
Gr 5
Anke Barabulea
Sonia Ko
Sonja Watson
Teaching site: 
General Gordon Elementary
Laurier Elementary
ProD for Elementary teachers