Water

What is Matter?

• It is the “stuff” that all objects and substances in the universe are made of.

• All matter has volume (takes up space) and mass (contains a certain amount of stuff).

• All matter can be detected and measured.

What is Density?

• The amount of matter in a given volume (mass per unit volume)

What is a Boiling Point?

• The temperature at which a substance changes from a liquid to a gas.

What is a Melting Point?

• The temperature at which a substance changes from a solid to a liquid.

What is Solubility?

• The ability to dissolve in another substance.

What are the States of Matter?

State of Matter

Defining Features

Solid • Keeps its shape and volume

Liquid • Takes the shape of its container

• Keeps the same volume, in a container or not

• Can flow

Gas • Takes the shape and volume of its container

• Can flow (through a room, for example)*Plasma is another state of matter

How does matter change?

• When a substance changes from one state to another it is called a phase change.

• There is no temperature change during a phase change, heat energy is moved.

From Solid to Liquid: Melting

• If you heat a solid, the particles in that solid will begin to move faster. If you keep heating it the motion will be great enough to overcome the attraction that locks the particles together.

• The melting point of ice is 0°C or 32°F

From a Liquid to a Solid: Freezing

• If you cool a liquid, the liquid’s particles will begin to slow down. If you keep cooling the liquid, the particles will slow to the point where they cannot overcome the attraction between them. At some point the particles will lock together and become solid.

• The freezing point of ice is 0°C or 32°F

From Liquid to Gas: Vaporization

• As a substance is heated, its particles begin to move faster and faster. During vaporization the fastest particles break free completely, becoming a gas.

• Boiling causes the liquid to vaporize.• The boiling point of water is 100°C or

212°F.

From Gas to Liquid: Condensation

• As a vapor cools, its particles begin to slow down. When the particles slow down so much they can’t overcome the attraction to the particles around them they clump together and form a liquid.

• The condensation point of water is 100°C or 212°F.

From a solid to a gas: Sublimation

• Skips the liquid state.• Occurs when more water molecules

become vapor than solid, and deposition occurs when more water molecules become ice than vapor.

• Frost and snow are formed this way.

What is water?

• H2O (2 hydrogen, 1 oxygen)

Water on Earth

• About 3/4 of the earth is covered in water.

• Two types: Salt water and fresh water

Distribution of Water on Earth

Salt water in oceans and lakes

Fresh water

Salt Water

• Makes up 97% of the Earth’s water• Found in oceans and salt lakes• We cannot drink salt water• Leaves salt crystals behind when it

evaporates. Water vapor is fresh water

Distribution of Fresh Water on Earth

Ice

76%

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apor

.037

%

Lake

s an

d Riv

ers .3

4%

Deep

Groun

dwat

er 1

1%

Shal

low G

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dwat

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2%

0%20%40%60%80%

Fresh Water

• Makes up 3% of the Earth’s water.• Found in glaciers, rivers, lakes,

groundwater, and water vapor.• Only 1% of the water on Earth is

available for human use.

Why is water weird?

• Water is densest at 4°C, when it is a liquid.

• Water expands when it freezes • Water can exist in all three states of

matter at the same time: liquid, gas, and solid.

Why is water weird?

• In the solid state, the particles of matter are usually much closer together than they are in the liquid state. So if you put a solid into its corresponding liquid, it sinks. But this is not true of water. Its solid state is less dense than its liquid state, so it floats.

• Water’s boiling point is unusually high. Other compounds similar in weight to water have a much lower boiling point.

Why is water weird?

• Water is sometimes called the universal solvent because it can dissolve so many things.

• It can also absorb a large amount of heat, which allows large bodies of water to help moderate the temperature on earth.

The Water Cycle

• The continuous process by which water moves from Earth’s surface to the atmosphere and back, passing through living and non-living parts of the environment.

• The water cycle is an almost “closed” system in which water moves through one main loop.

The Water Cycle

The Water Cycle

• Water evaporates into the atmosphere, moves through the atmosphere as water vapor, condenses into clouds, and falls back as precipitation.

Evaporation and the Water Cycle

• Water vapor moves through the atmosphere

• Water vapor is fresh water, salt remains in the ocean.

• Plants give off water through their leaves. This is called transpiration.

• Water from people, soil, puddles, etc. also contribute.

Condensation and the Water Cycle

• Clouds form when water vapor cools and condenses into tiny water droplets.

• Water vapor can also condense when it reaches its dew point (morning dew, a cup sweating).

Precipitation and the Water Cycle

• Eventually, the water droplets of a cloud get so heavy that they fall back to the earth as precipitation.

• Most precipitation falls right back into the ocean.

Precipitation on Land

• Some evaporates right away• Water that flows over the land is

called runoff.• Some water is collected and stored

as– Groundwater– Glaciers– Lakes, reservoirs

The Water Cycle

Water in Las Vegas

• Las Vegas gets 88% of its water from the Colorado River, the rest comes from groundwater pumped out of wells.

• Runoff (mostly urban) flows through the Las Vegas Wash and heads to Lake Mead.

• Most of the water in Lake Mead comes from the Colorado River. Lake Mead was created by the Hoover Dam.