You may have noticed by now that the Scientific American Blog Network is having something of a Chemistry Day.
Reading about chemistry is fun, but I reckon it's even more fun to do some chemistry. So, if you find yourself with a few moments and the need to fill them with chemical fun, here are a few ideas:
With red cabbage and hot water, you can make a solution that will let you tell acids, bases, and neutral-pH substances apart.
Spend the afternoon classifying the substances in your refrigerator or pantry! Audition alternatives to vinegar and baking soda for your papier mache volcano!
Gather up some plant matter and see what colors you can develop on eggshells.
One interesting thing you might observe is that empty eggshells and eggshells with eggs in them interact differently with the plant pigments. Ponder the chemistry behind this difference ... perhaps with the aid of some cabbage-water indicator.
Grab some markers (black and brown markers work especially well), lay down some filter paper (or a paper towel or a piece of a coffee filter), and just add water to observe the pretty effects created when some components of ink preferentially interact with water while others preferentially interact with the paper.
If you like, play around with other solvents (like alcohol, or oil) and see what happens.
Even just making canonical mayonnaise is a matter of getting oil and water to play well together, making use of an emulsifier.
But things get interesting when you change up the components, substituting non-traditional sources of oil or of emulsifier. What happens, for example, when an avocado gets in on the action?
Molecular gastronomy isn't just for TV chefs anymore. If you have a decent kitchen scale and food-grade chemicals (which you can find from a number of online sources), you can turn potables into edibles by way of reactions that create a "shell" of a membrane.
Sometimes you can control the mixture well enough to create little spherical coffee caviar or berry-juice beads. Sometimes you end up with V-8 vermicelli. Either way, it's chemistry that you can eat.