[Analytical chemistry] is probably one of the things that’s easiest to tie back to their own experiences. Because it’s very easy to link the idea of the importance of chemical measurement, is actually pretty easy to get across.
Students from high school might understand that vinegar for example is a weak acid compared to hydrochloric acid, but they never knew why. And you could then show them that with equilibrium, this is why. And all of a sudden they’re, 'oh, I’ve always known that I shouldn’t spill HCL on my hand, but I can spill vinegar on my hand and put it on my fish and chips'... Those sorts of moments can really... the students go ‘oh wow.’
Bring in industrial processes. For example, the Bayer process, which is the principal industrial means of refining bauxite to produce alumina (aluminium oxide). Talk about the conditions used for that. So how you can increase the yield of the reaction? The Bayer process is done at high temperatures and high pressures. This demonstrates ways to increase the amount of product.
Use several real life examples with different ways of causing the equilibrium to shift. Swimming pool chemistry:
HOCl can enter the cells of undesirable organisms to kill them, but OCl- can’t, hence if the equilibrium is too far to the right it won’t act effectively. If you add acid (say HCl) the position of the equilibrium shifts to the left, producing more OCl-. That’s partly why the pH of the pool is important.
Use everyday examples. A great question to have at the end of your lecture would be ‘What is reduced when my bike rusts?’ They might understand that their bike rusts, but what is reduced? Oxygen and water are reduced. But we don’t see the reduction, we just see the iron changing. You have done your job well if someone asks the question ‘What is reduced when my bike is oxidised?’
Use drugs as an example of the relationship between how much of a species is protonated and how much is non-protonated. This is an equilibrium process. For a carboxylic acid drug, if it’s protonated it’s not ionic, if it’s not protonated it’s anionic. And if it’s going from gut into blood for example, whether or not it goes through the membrane will depend upon the pH of the system.
Relate equilibrium to students’ own experience of strong versus weak acids. For example, you can put vinegar on your fish and chips but not HCl. From high school they might have an understanding that vinegar is a weak acid compared to hydrochloric acid, but they never knew why. And you could then show them that with equilibrium, this is why.
