How does water turn to steam? Why doesn't the whole pot of water instantly turn to steam the minute the water starts to boil? What is the scientific explanation for how water changes from a liquid to a vapor? If you need answers for these questions, this simple primer can help you out.
Molecular Changes
To understand how water changes from ice to water and then to steam, you have to understand that water is made up of tiny parts called molecules. These molecules consist of two parts hydrogen and one part oxygen, hence the name H2O.
When H2O molecules exist in the temperature range of 32 degrees Fahrenheit to 211 degrees Fahrenheit, they pack together, yet they remain able to disconnect from one another and reconnect with other molecules of the same makeup, making water fluid. When these molecules reach a temperature of 212 degrees, they suddenly lose that ability to stick together and instead need a certain amount of space between them, causing them to separate out and become a gas as they change state from liquid to gas form.
Stovetop Steam
When water is placed in a pot and then heated by a burner on a stove, the water will simply get hotter and hotter until it reaches the point where it turns to steam and rises into the air. Water can never get hotter than 212 degrees; at that point, it becomes a vapor, known as steam. Steam itself can get much hotter than 212 degrees. With the proper pressure, the temperature of steam can reach just over 700 degrees Fahrenheit. Above that temperature, the bonds that hold water molecules together break down, and the water turns into pure hydrogen and pure oxygen gases.
To demonstrate how this process works, heat a pot of water on the stove until it is boiling rapidly. Hold an empty plastic bottle over the pot, with the open mouth of the bottle facing the boiling water until the bottle fills with steam. Quickly cap the bottle and place the sealed bottle in the freezer.
Allow the bottle to cool for ten minutes, and then check on it. The bottle will have collapsed in upon itself. This happens because the steam, which needed more space between each molecule, has now cooled, condensed and created water or ice in the bottom on the bottle. The rapid change in air pressure inside the sealed bottle creates a suction force that pulls the sides of the bottle in upon itself.
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 | Has your child asked, "How does steam power work?" Check out this simple explanation and a fun experiment to try at home to illustrate what steam can do. |
 | Why is steam hotter than boiling water? Use this simple experiment to help kids understand the difference between steam and water. |
Are your children asking, "What causes steam?" Use this simple experiment to teach them about steam and introduce them to some basic rules of chemistry. |
Is steam hotter than boiling water? Sometimes it can be, and sometimes it can cause burns. |
