How can liquid nitrogen be so cold but not freeze into a solid?
asks Michael Chapman, a student in Holtsville, NY. Solid, liquid, or gas? Many things are solids at room temperature and normal air pressure — like a chunk of iron, or a stick of butter. Others are liquid — like water, or olive oil. And still others are gases–like oxygen or nitrogen. The universe is full of substances that behave differently at normal atmospheric pressure and temperature here on earth. Fast fact: While we depend on oxygen for our very life, oxygen isn’t the main gas whizzing around in the air. Earth’s air, in fact, is 78 percent nitrogen gas. The “boiling point” is the temperature at which a substance turns from liquid to gas. Water’s boiling point is 212 degrees F. We can turn water to gas — steam — by putting a pan of it on the stove to heat. Eventually, the water will begin to bubble, and we’ll see steam escaping into the air. The water has changed from one state — liquid — to another: gas. Nitrogen’s boiling point must be very different than water’s, if nitrogen is
