Outcomes

In order to form vapor, the molecules of the liquid must overcome the forces of attraction between them.
The temperature of a boiling liquid remains constant, even when more heat is added.

Specification References

5.10 Understand that a substance can change state from liquid to gas by the process of evaporation or boiling.

Pupils are given a range of water samples and are asked to determine which sample is ‘contaminated’

Find the boiling point of water samples (one distilled water/ other will salt added)

Bunsen burner kit, beakers, thermometers, samples of distilled and contaminated (salt) water

www.ilpi.com/msds/ref/gifs/statesofmatter.gif (image of the three states of matter)
www.harcourtschool.com/activity/states_of_matter/

Let the students represent particles of matter. Sitting in their chairs, the students represent the orderly arrangement of particles in a solid. An increase in the temperature of a solid will increase the vibrations of the particles and thus their kinetic energy. As energy is added at the melting point, only the potential energy of the particles is increased such that they will break loose from their fixed positions and become more disorganized. Use the students to illustrate this. In the liquid state energy added increases the kinetic energy. The particles are free to slip and slide over one another and they will move back and forth at a faster rate. You can go onto representing a gas.