The first lesson in the chemistry class is to define what chemistry is! Students when asked what chemistry is, say; ‘reactions’ ‘acids’,’stuff in the lab’ and for some the ultimate bad word ‘chemicals’. We need to point out that we are all made up of ‘chemicals’ and the subject is the study of changes that substances undergo – as when you eat a banana and it becomes you. We also need to point out that some changes give rise to new substances and some do not – chemical and physical changes. There should be demonstrable experiments for students to decide whether a change is physical or chemical. The easiest is:
1. to heat
2. add to water
3. leave out in air.
We will try all three.
Some equipment that will be good to have are, a few hard glass test tubes, a boiling tube, a test tube holder and an alcohol thermometer (-10°–110° C). Most other equipment can be improvised.
Heat in separate test tubes the following chemicals. The table shows what will be observed.
The author works with Centre for Learning, Bengaluru. She can be reached at firstname.lastname@example.org.