Temperature, heat and molecules

When heat energy is given to a material, its temperature usually rises. At a molecular level, the extra heat energy causes the molecules that make up the material to move more quickly (we say that they have increased random thermal motion). So temperature can be thought of as a measure of the average kinetic energy of the molecules in a material.

Learning outcomes

• Appreciate that molecules move faster as the temperature increases.
• Begin to understand the relatonship between temperature and heat.

Instructions

The 400 molecules will start moving as soon as the page loads.

You can adjust the temperature using the slider towards the top of the screen.

The molecules may occasionally stick together, but should break apart again.

Questions

1. What happens to the molecules at zero temperature?
2. When you increase the temperature slider, is this equivalent to a positive or negative heat energy change?
3. If heat was put into the system at a constant rate, what would happen to the temperature as the system crossed a phase boundary (e.g.: liquid to gas)?