Caffeine

I know that the posts on this blog are almost always extremely boring. Normally, I don't have any good excuse for writing such boring material, but tonight I do. Once again, I'm having trouble falling asleep, so maybe some boredom is in order.

So, here's what I'm thinking about tonight. I know that tea has caffeine in it, but I find myself thinking about what caffeine is. Now, the truth is that I have no idea what caffeine is. Does that sound like an absurd statement? Let me clarify: I know how people use the word "caffeine," and I know that "caffeine" appears on the label of migraine medicine, and I know what foods and drinks are said to contain caffeine. I also know that caffeine is said to cause insomnia in some people, and is reputed to lead to increased mathematical abilities (all other things being equal). But my point is that I don't know what caffeine is in a scientific way.

So let me start my scientific pondering in this way: I have read that an 8 ounce cup of green tea has about 30 mg (milligrams) of caffeine in it. Now, that is a claim about the weight (or mass) of this substance in a cup of tea. But how much caffeine is that? If the cup of tea evaporated and left the caffeine behind, would their be a visible residue? (I don't know if that's even possible.)

Let's get an idea of how much 30 mg weighs. It turns out that 30 mg is 0.03 grams. One teaspoon of volume of water weighs almost 5 grams. That means that the water used in making one cup of green tea is about 165 times as heavy as the caffeine in the tea. Equivalently, if you remove the caffeine from 165 cups of green tea, that amount of caffeine would weigh the same as one cup (8 ounces) of water.

What about the volume of the caffeine in one cup of green tea? The infallible internet has provided me with the proposition that 1 cubic centimeter of volume of caffeine weighs about 1.23 grams. Since one cup of green tea has 30 mg of caffeine, the volume of caffeine in one cup of green tea is 24.4 cubic millimeters. So, imagine a cube that is 24.4 millimeters on each edge, and that would be the volume of caffeine in one cup of green tea. This would be equivalent to 0.005 teaspoons, or one part out of 200 of a teaspoon.

So, I guess as far as weight and volume are concerned, a cup of green tea has very little caffeine. It has surprised me then that one can easily buy pure caffeine. It seems that any tangible quantity of pure caffeine would be enormous compared to the amount in common beverages. I found that people have died from taking as little as four grams of caffeine, and that you can buy 100 grams of pure caffeine on Amazon. The label of the product I found on amazon says that 2 grams will send you to the ER. It's crazy to think there is even demand for such a product. Caffeine is common enough, and 100 grams of such a potent and seemingly benign substance seems like an insane amount to want to possess.