G3_Water and the Three States of Matter 400 – 500L_04

Remember what you learned about water as a gas? That’s right, you cannot see it. Now look at the picture of the cloud. What is the cloud made of? No, it can’t be a gas; we would not be able to see it. It must be a liquid. It could even be a solid if it is cold enough. Yes, a cloud is made of tiny particles of water. These tiny particles may be liquid water or solid ice. They are so small that moving air holds them up in the air.

Water’s Changing State

Water is used a lot for cooking our food. Some foods need to be cooked in boiling water. The pot of water is placed on the stove. As the heat from the stove is transferred to the pot, the water begins to boil. Bubbles will form in the water and steam will start to rise from the pot. When this happens, water has reached 100 degrees Celsius, its boiling point. Liquid water is now turning into a gas.

Can you recall the name of that gas? What if the pot is left on the stove? That’s right! Eventually, all the liquid water will turn into a gas. The water vapor becomes part of the air. What if the water was not heated on the stove? Could it still turn into water vapor? Does liquid water only change to a gas if it is boiled?

Evaporation

Imagine heavy rain falling from the sky. It is so wet you can’t go outside to play. Finally, the rain has stopped. You can see puddles on the road in front of your home. You want to ride your bike, but your mom says you must wait for the road to dry. You wonder if this will take a long time. Don’t panic! It won’t take too long. Today, the weather is in your favor.

The Sun is back out and shining brightly. The temperature outside is warming up as well. The puddles are not very deep, and there is even a light breeze blowing. All these factors will help change the liquid state of water to its gaseous form. The Sun’s energy will heat the water in the puddles, and the water will begin to change states and turn into water vapor. This change, when a liquid turns into a gas, is called evaporation.