What States Does Water Occur In?
Water occurs in three primary states—a solid (such as ice), a liquid or a gas (such as a vapor).
Water becomes solid when it meets its freezing point. If you remember, we learned all about freezing points in the BettyLab experiment, "Ice Cream in a Bag." Liquid water—the form many of us are most familiar with—is wet, fluid and what we drink. The last form water takes is gas or vapor, and that’s what we’ll be focusing on in this experiment. One example of water becoming vapor is when we boil water.
What is Water Vapor?
Water vapor is gas. It’s super tiny particles of water that float in the air. Water vapor is always present; you just can’t always see it! Let’s take a look at boiling water and how that produces water vapor. Here the water changes from a liquid to water vapor. As our water vapor starts to cool, we’re able to see it. Any guesses on what it is? If you guessed “steam,” you’re right. Another example of water vapor that we can see are clouds.
How Does Water Vapor and Pressure Create Popcorn?
A kernel of popcorn contains a small amount of water, approximately 14%. When our kernels are heated and reach water’s boiling point, the water inside the kernel transforms from a liquid to a vapor. The water vapor is then trapped inside our kernels (but not for long)! So what makes popcorn pop? Eventually, enough pressure is built up inside and bursts through the shell and ‘POP.’ The pop is a chain reaction due to the escape of the pressurized water vapor through the kernel shell.
Why Do Some Kernels Not Pop?
There are three main reasons why a kernel didn’t pop. The first is a faulty shell, this could be that there are cracks in the shell, so pressure can’t properly build up. The second is there may not be enough water in the shell for water vapor and pressure to form. The last is the heat! Your heat setting may be too low for the kernels to pop.