As I was considering the experiment detailed here, I also began to think about what motivates me to explore ways of doing experiments. I enjoy chemistry a great deal and when I read about a reaction, my first response is; can I see that? If I search (much easier nowadays with the Internet) I may find links to the experiments. They are usually from college teaching labs, simple enough to do but using chemicals not usually available to us. Many chemistry textbooks at the college and high school level detail a very easy to do experiment to show the formation of nylon by polymerisation. Layer the two monomers in a beaker and as the nylon forms at the interface pull it out. Really simple but… the chemicals are not available easily here. A young friend interested in science also shared his frustration, “All the science activity books show cool experiments, but they casually say ‘get one litre of liquid nitrogen’” It is hard. Nowadays, of course, there is always YouTube, better than nothing but still not the real thing.
Why try so hard to set up experiments? I can think of two reasons. First, most students find chemistry hard, because they are expected to remember details they have not seen. Seeing the reaction acts as an aid to the memory. Second is my learning. As I try to set up and do an experiment, I begin to realize what can be confusing and can be misunderstood. Why are we assuming that what we describe is happening? All this forces me to think about the theory I am trying to teach and, I hope, makes my explanations clearer.
Continuing the theme of the last columns, I wanted to explore digestion of fats, the third food group that students had learnt about. Checking on the web, I found experiments that used Pancreatin (an enzyme) and bile salts. Chemically, the digestion of fats and oils gives fatty acids and glycerine, so a pH meter was used to determine the change in pH. This was where my exploration began. Where can I find lipases (enzymes that digest fats)? Do germinating oil seeds make lipases to break down their food store to grow? Can indicator solution be used instead of a pH meter; will it show enough of a colour change? Will the lipase from groundnuts digest all fats or only groundnut oil?
The author works with Centre for Learning, Bengaluru. She can be reached at email@example.com.