Background
Heating and cooling substance may bring about one or more physical changes in a substance. Regardless of the change, at the particle level, changes in their motion invariably take place which at times can be dramatically demonstrated.
Resources:
M4 Chemistry Matter II: State and Energy. PowerPoint slides on the relationship between state of matter and energy content of particles in a sample of the matter.
Discrepant Event
The video below shows three different demonstrations looking at the effect of cooling a squash ball, a rose and a small balloon filled with air using liquid nitrogen. Watch the video to see what happens.
And the questions are:
- Why did the squash ball and the rose shatter like glass?
- Why did the balloon deflate when introduced into liquid nitrogen and then spontaneously re-inflate when taken out?
Concepts involved:
- cooling, heating, heat, energy/heat transfer/exchange, motion of particles, pressure, temperature.
