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.
How Does Water Evaporate? exercise
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Can you figure out the process?
HintsThe main reason this process happens is because of heat.
Imagine having a sponge that is wet in your hand. What happens to the water on the sponge when you leave it outside in the sun?
SolutionThe process that occurs when water slowly changes from a liquid state to a gaseous state without boiling is called evaporation.
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Do you know what vaporization is?
HintsThe boiling point of water is 212 degrees Fahrenheit.
Vaporization happens when a liquid is heated to its boiling point.
SolutionThese are the correct answers:
- When water is heated to a temperature of two hundred and twelve degrees Fahrenheit, it boils.
- During vaporization, water changes from a liquid to a gas when it is boiled directly with the heat source.
- If the water boils and is vaporized, it is only invisible for a short time.
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When does condensation happen?
HintsCondensation is the opposite of evaporation.
Condensation happens when water vapor in the air cools down.
Solution- When the water vapor touches the colder air, it goes through a process called condensation.
- When water boils, this creates tiny water droplets that rise to the surface.
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What affects the speed of evaporation?
HintsEvaporation is slower on humid days.
Windy days can help evaporation happen faster.
More water is exposed to the air in a big puddle, so more of it can turn into vapor.
SolutionThere are different factors that affect the speed of evaporation.
For example:
- The temperature: Evaporation is faster when it's warm and sunny outside.
- The surface: If water is spread out in a large puddle, it will evaporate faster than if it is placed in a small puddle.
- Air movement: When the wind blows, it takes away the water vapor, making more room for new water molecules to evaporate from the surface.
- The humidity: If the air is already full of water, it's harder for more water to evaporate into it.
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Can you recognize the processes happening?
HintsImagine water in a puddle or on your clothes drying up and disappearing.
The water evaporates because of the Sun's heat.
Vaporization means both evaporation and boiling.
Picture a window on a chilly morning. When warm breath turns into tiny droplets, you're witnessing a process called condensation.
SolutionThe correct answers are:
- Evaporation happens when water turns into water vapor.
- Vaporization happens when boiled water turns into water vapor.
- Condensation happens when water vapor touches the colder air.
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Can you recognize the processes happening in these situations?
HintsThe heat from the Sun gives the water more energy, and some of the water turns into invisible vapor and goes up into the air.
This process is called evaporation.
Have you ever noticed how your bathroom mirror gets all foggy and covered in tiny water droplets after you take a nice, warm shower?
The mirror is much colder than the warm air from the shower. So, when the warm air reaches the mirror, it cools down quickly.
This process is called condensation.
SolutionUma observes steam-like wisps rising from the puddle as the sun shines brightly in the sky. This is because the sun's warm rays give the water in the puddle special energy. Some water molecules become so excited that they escape the puddle and become invisible water vapor that floats up into the air. Uma observes evaporation.
As the sky changes and becomes cloudy later in the day, something magical happens. The water vapor that rises in the air starts cooling and slowing down. They get close together, just like friends holding hands. Uma soon realizes that clouds are forming in the sky. The clouds are like cozy huddles of tiny water droplets created from the water vapor that has cooled down. Uma observes condensation.
Uma's mom is boiling water to make tea now that it's afternoon. Uma observes the water inside the pot becoming warmer and warmer. All of a sudden, she sees bubbles coming out of the bottom of the pot. 'Look, Mom! The water is dancing!' Uma shouts out. Mom grins and affirms, 'You're right, Uma!' The water is turning into vapor. Uma observes vaporization.
One sunny afternoon, Uma decided to play with her favorite puddle outside. She noticed that the water in the puddle was slowly disappearing, and she wondered where it was going. Intrigued, she placed a small plastic container filled with water next to the puddle. As the warm sun continued to shine, Uma observed something magical happening. The water in the container started to disappear just like the puddle, but this time, it wasn't going away completely. Instead, it formed tiny droplets on the lid of the container. Uma smiled and thought, 'The water is turning into tiny clouds!' Uma observes both evaporation and condensation.
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