Chemistry is the science of matter and the changes it undergoes during chemical reactions. In this section, learn about everyday chemistry, from chlorine beach to helium, and even why chocolate turns gray.

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Why is carbon monoxide poisonous?

I have heard that carbon monoxide is extremely poisonous. Can you explain why?

What is dioxin?

What is dioxin? There's a lot of discussion going on in my town about dioxin and its dangers.

How do you write the chemical reaction that takes place in a smoke detector?

Chemical formulas provide a concise explanation for reactions. In this article, we explain the formula for the reaction in a smoke detector.

What causes helium balloons to lose their lift after a day or two?

Scenario: A helium balloon is up against the ceiling one day, and the next day it's on the floor. Does the balloon fall because the helium leaks out, or because the helium molecules slow down due to decreased pressure?

How Anesthesia Works

If the idea of being completely knocked out by a cocktail of drugs while doctors operate on you freaks you out, you're not the only one. But that's not what anesthesia is all about it -- and it might scare you less if you understand how it works.

How Caffeine Works

About 90 percent of Americans consume some form of caffeine every day: It's our most popular drug by far. What's so special about this stimulant?

How Helium Balloons Work

Helium balloons tend to fascinate adults and children alike (and it's not just the Donald Duck voice thing, though that is a big draw). Learn all about helium and why it floats!