So far, we’ve extracted indicator from red cabbage, used vinegar to clean copper, and burned things to produce heat and light. All these are useful things, and all these are reactions. The more you study chemistry, the more you realise that it is not some abstract theory apart from daily life. It’s everywhere. It’s in everything.

One of the most important reactions in our culture is the one that turns sugar into carbon dioxide and ethanol. We’ve used it since ancient times for two purposes: to make alcohol to drink, and to make bread rise. It’s an interesting example because it depends absolutely on another organism: yeast. We don’t do the reaction with chemicals. We put living yeast into a mixture, and we wait for it to feed on the sugars and produce alcohol and gas. Then we filter the yeast out and drink the alcohol, or we put the bread in the oven and let the heat kill the yeast.

Breadmaking is fun and tasty. Try it out, it’s cool.