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# Try This: Boiling Ice by Tom Robinson

Most materials with mass usually exist in three different phases: solid, liquid, or gas. Each of these phases has its own set of unique properties, and those properties describe the material in very special ways. Take water, for example. Do you know what it looks like in its solid, liquid, and gas forms?

solid: a state in which a material is hard and usually very dense. A solid will maintain its shape even outside a container.

liquid: a state in which a material is a fluid and is less dense than a solid, yet more dense than a gas. A liquid will assume the shape of its container, but won't expand in the container to do so.

gas: a high-energy state in which a material is a collection of molecules moving in random motion generally at high speeds. A gas will assume the shape of its container, but it will expand or compress in order to do so.

Second Law of Thermodynamics: heat always flows from a hotter object to a colder object.

## QUESTION

Why does a pot of boiling water stop boiling when an ice cube is put in it?

## MATERIALS

Pot of water

Several ice cubes

Stove

## PROCEDURE

• Set the pot of water on the stove and turn the burner on high until the water boils. You might need to ask for permission or some assistance for this step.

• Once the water has come to a steady boil, place several ice cubes into the pot, keeping the water boiling. Observe what happens.

## WHAT'S HAPPENING

The boiling should have stopped immediately. Why is this? It's because of the Second Law of Thermodynamics. According to this law, the heat coming from the burner will always flow to the coldest object in the pot — in this case, the ice. So the heat from the burner stops making the hot water boil and starts making the solid water melt.

## FOLLOW-UP

When the ice finally melts, will the water start boiling right away?1 Once the water boils again, notice the steam that rises from the pot. Where does it come from? It's just the same water in another state, a gas, and it's called water vapor. We see it when we take a shower in a cold room, and whenever we see clouds or fog in the sky.

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## Science Online

In 1869, a Russian chemist named Dmitri Mendeleev arranged all the known material in the universe into a chart that is now known as the Periodic Table of the Elements. Each element is defined by a certain arrangement of protons, electrons, and neutrons. The table is organized so that the elements are listed in order of their Atomic Number, the number of protons in the element.

Below you will find three links to interactive sites that show the Periodic Table.

Chemical Elements

www.chemicalelements.com

Chemicool

www.chemicool.com

Web Elements

www.webelements.com

## Fun Facts

It takes nearly seven times more energy to melt 1 kilogram of ice than it does to boil 1 kilogram of water!

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