Forms of Water

8/13/2019 Forms of Water

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by Kathleen Powell


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Introduction

How would you answer this riddle?

Sometimes I am a liquid.

Sometimes I am a solid.

Sometimes I am a gas.

You use me every day.

What am I?

If you answered water, you are right! Water

can change to all of these forms.

But do you know how?

Water in three forms

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Heat and Cold

Heating and cooling can make water change

forms. The temperature of the water affects

how the water changes.Heating water to 100 degrees Celsius makes

it boil. Cooling water to 0 degrees Celsius makes

it freeze. You can find these temperatures on a

Celsius thermometer.

Another temperature scale is called the

Fahrenheit scale. On the Fahrenheit scale, water

boils at 212 degrees. It freezes at 32 degrees.

Weather reports in the United States usually

describe temperatures using the Fahrenheit scale.

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Evaporation

Heres another riddle.

What gets wetter the more it dries?

A towel! (As it dries you, it gets wet!)

What happens when you put a wet towel

into a dryer? The heat from the dryer dries the

towel. Remember, temperature affects waters

form. What happens to the water that is in thetowel? How does it change?

The heat makes the water evaporate, or

change from a liquid to a gas. When water is

a gas, it is called water vapor.

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You cant see water

vapor. Its invisible.

Think of a kettle ofwater on a stove

burner. When the

water boils, you

can see steam.

Steam isnt madeof just water vapor,

however. Steam is

also made of tiny drops

of liquid water. Those

drops are what you see whenyou see steam.

What do you think would happen if the water

in the kettle kept boiling? All of the liquid water

would evaporate, or change to water vapor.

Condensation

You have seen how liquid water can change

to water vapor. But can water vapor change

back to a liquid? Lets find out.

steam

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Suppose that its a hot day. You want to have

a glass of cold water. You put ice cubes into

a drinking glass and fill the glass with water.

Then you let the glass sit in the warm air. Whathappens to the outside of the glass?

After awhile, you see that the outside of the

glass has beads of water on it. Can the water

be leaking through the glass?

What reallyhappens is called

condensation. Water

vapor in the warm

air turns into a liquid

when it touches thecold glass.

condensation

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More Condensation

Are you ready for another riddle?

What always falls but never gets hurt?

Rain!

You have seen some ways in which liquid

water can change to a gas. What do you think

happens to all of that water vapor in the air?

When the water vapor cools, it changes todrops of liquid water. The water drops form

clouds. Just like the part of steam that you can

see, clouds are made of tiny drops of water. If

the drops get too big and heavy, the water falls

to Earth as rain.

DTemperatureChanges

Depending on

the temperature,

water may fall assnow or rain.

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Water Size

You have read about some ways in which

water changes form. If water freezes, it

changes to a solid. If water boils, it changesto a gas called water vapor. If the water vapor

cools, it changes to a liquid. Did you know

that the amount of space the water takes up

also changes?

Suppose you put a container of liquid waterin the freezer. Would the ice it changes to take

up as much space as the liquid did? Most things

take up less space in their solid form. But not

waterit takes up more space, not less.

Solid Water CIce in your

freezer takes

up morespace than

liquid water.

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Think and Write

1. Name the three forms that water can take.

2. What makes water evaporate?

3. What word describes what happens when

water vapor cools and becomes a liquid?

4. Persuasive Do you think Fahrenheit or

Celsius thermometers should be used in

your school? Write a letter to your principal

that explains your ideas.

Hands-On Activity

Temperatures Measure the temperatureof water in a cup. Add ice cubes to the

water. Wait one minute. Now measure the

temperature again. Write the temperatures

you measure as either Celsius or Fahrenheit.

School-Home Connection

Riddle Ask family members to answer the

riddle on page 2. After they answer, explain

to them how water can change into three

different forms.

Documents

Forms of Water