Written by adam on Jan 31, 2006
Boiling Water: A Beginner's Guide
Filed Under: How To
I've been thinking about boiling water for a while now. This is a subject that is often equated with not being able to cook. You've probably heard jokes about someone being such a bad cook that they couldn't boil water, or they are so bad a cooking, they could even burn water. TheWife mentioned that boiling water was an advanced task for her father, a man whose food repertoire is fried bologna sandwiches and PB & J's.
All joking aside, boiling water is not hard.
Put water in container. Apply heat to container. Wait.
It's that simple, right? Maybe. But as easy as that might be, there's a lot going on that needs to be addressed, as well as the different types of boiling that exist. And let's not forget altitude. You folks in Colorado have some different rules when it comes to cooking that Kraft Macaroni and Cheese.
Get to the Point
Boiling point is the physical point at which a liquid becomes a gas. In the case of water, boiling point is 100 degrees Celsius, or 212 degrees Fahrenheit. This is at sea level. Thing change when you go higher in elevation. When the air pressure is lower, the water vapor molecules have less force to push against to get out of their liquid prison. (see below)
Double Bubble Toil and Trouble
So why does the water get all bubbly when boiling? The bubbles that we see forming in heated water are basically molecules of the water that are being changed to vapor, or air and are rising to the surface.
The two principal factors that affect boiling are the pressure and the temperature. Under one atmosphere of pressure, pure water boils at 100 C. If the pressure changes, then the temperature will also change. More pressure means that the water vapor has to push harder on the air above it and less pressure means that there is less air to push out of the way. Because when we increase our altitude we generally find an accompanying decrease in atmospheric pressure, changing altitude can change a boiling point. Source: The Center for Astrophysical Research in Antartica
So in higher altitude areas, the boiling point of water is lower than the 212 degrees that it is at sea level. This, of course, varies from area to area, and you may want to do a little research on the web if you live in high altitude like Denver or boulder to find out how to compensate for this change. The important issue is temperature. Water in Denver may boil at a lower temperature than, say, Houston. However, did you get that water hot enough to cook with? That's the test, and you may want to have an instant read thermometer handy to check, just in case.
Just imagine what the climbers on Mt. Everest have to go through.
Some tips for boiling:
1. If boiling water for pasta, bring the water to a full rolling boil with the lid off.
2. If you put the heat on high, turn it down slightly when you add the food. This will help you avoid the dreaded "boil over."
3. Bringing a pot of water to boil goes faster if you have a lid on it.
4. Be careful of the steam. If you remember from your physical science classes, steam is water molecules that are traveling faster than the liquid molecules. It can burn you worse than the liquid itself. When I take the lid off a pot of boiling water, I usually turn my head for 3 seconds.
Sources: University of Chicago Department of Astronomy and Astrophysics, Big Green Egg