How Does Water Evaporate?
Basics on the topic How Does Water Evaporate?
Why does Water Evaporate?
You have probably watched an adult boiling pasta by heating a pot of water on the stove. When the water gets hot, it gradually starts to evaporate. You can see the steam rising. Then, the hot air above the water surface absorbs the tiny water droplets. This is the transition of water from a liquid to a gaseous state. This happens at a temperature of 212 degrees Fahrenheit, the boiling point of water. The water vapor is then very hot and humid. But how does water evaporate below 212 degrees Fahrenheit?
What is Evaporation?
When liquid water decreases without boiling, it is called evaporation. You are probably familiar with this with puddles after rain. After a shower, water puddles stay on the street. After time, they become smaller and eventually disappear completely; this is evaporation. What happens during the evaporation of water? Let’s take a look at the definition of evaporation:
Evaporation means that water slowly changes from a liquid state to a gaseous state without boiling.
This means that, like in the pot of boiling pasta, tiny water droplets transition into the air. However, this happens very slowly and can take several days. How does water evaporate at room temperature?
Water has the wonderful ability to take on different forms. These are called states of matter. It can be liquid, solid, and gaseous and change back and forth like a superhero. The state it takes depends on the temperature.
When it is cold, like in winter, it becomes solid. Water freezes at 32 degrees Fahrenheit and turns into ice. You can even ice skate on the frozen lake water.
Above 32 degrees Fahrenheit, water is normally liquid and interacts with the air. This means that a part of the tiny water particles rises into the air and becomes gaseous, even if you can't see it.
When the water is heated strongly, many water particles are absorbed by the air in a very short time. Why does water evaporate faster at higher temperatures? This is because warmer air can hold more moisture. It can better retain the water particles.
Experiment at Home: Water Evaporation
If you want to observe how long it takes for a bowl full of water to become empty, try the experiment from the video.
Fill two equally sized bowls with the exact same amount of water and place one in a sunny spot in the house and the other in a shady, dark spot. With a little patience, you can observe how the water gradually decreases and evaporates. Do you have an idea which of the two bowls will empty faster? If you like, take a notepad and a ruler to measure the water level.
Frequently Asked Questions about When does water evaporate?
Transcript How Does Water Evaporate?
Dogs love day-old water, so Uma left some in the teapot for her tea. Now all she has to do is turn on the stove. But wait! Where did the water go? It's all gone! Let's solve this mystery by asking ourselves, "How does water evaporate?" Before Uma could even turn on the stove, the water in her pot had gone through "evaporation", or changed from a liquid to a gas. There are different reasons why water evaporates. The main reason this happens is because of heat. The warmer water gets, the faster it "evaporates" and becomes "gaseous", or turns to gas. When water turns into gas, we call it "water vapor". Normally, we cannot see water vapor with our eyes because it is so small. But, we illustrated it here so that you can see it better. Now, Uma has refilled the pot with water and heated it to a temperature of two hundred and twelve degrees Fahrenheit. Then, the water boils. When water boils, it goes through a process called "vaporization." Do you know the difference between evaporation and vaporization? During evaporation, water changes into a gas without any direct heat source. However, during vaporization, water changes from a liquid to a gas when it is boiled directly with a heat source. If the water boils and is vaporized, it is only gaseous and invisible for a short time. Above the pot, the hot water vapor meets a lot of cold air. When the water vapor touches the colder air, it goes through a process called "condensation." This creates tiny water droplets that rise to the surface. We can see these tiny droplets of water when we cook. That's the steam rising above the pot. But be careful!! We have to be mindful with the term "water vapor": Water vapor means that water is "gaseous" and "invisible", just like air. At home, however, we often call the steam we see over a hot pot water vapor. But this isn't actually correct. What we see above the pot are tiny droplets of liquid water. This is not true water vapor, it's more like a ‘cooking cloud’ or something like that. Do you have a better phrase for the fog that forms over a pot of boiling water? Share it in the comments below! Now let's briefly summarize the video and then see what Uma is up to. Water always evaporates. The warmer the water, the faster it evaporates. When water boils on a heat source, it then vaporizes. Condensation happens when water evaporates briefly and condenses again very quickly, so that tiny droplets of water rise up for us to see. What about Uma? Her tea is finally ready. And now she can enjoy it. OUCH! It's still pretty hot, better wait a second.
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