Right: Molecules of polyethylene the most common plastic material are formed by a huge number of ethylen molecules ("mouse pairs") by forming one long molecule chain ("row of mice").
* Left: Heat a piece of polyethylen from a plastic bag in a 10-ml bottle which is connected to a smaller bottle by a tubing and a wire. This bottle contains bromine water.
Observation and Explanation middle: The molecule chains of polyethylene are cracked by heating. The fragments contain unsaturated hydrocarbons which decolourize the bromine water by addition.