Properties of Properties of WaterWater

Earth has been called the “blue planet”Earth has been called the “blue planet” From space, its surface appears to be From space, its surface appears to be

mostly oceans of liquid watermostly oceans of liquid water Water vapour is found in Earth’s Water vapour is found in Earth’s

atmosphereatmosphere Frozen water occurs on mountaintops Frozen water occurs on mountaintops

and at the North and South Polesand at the North and South Poles The bodies of animals and plants consist The bodies of animals and plants consist

mainly of watermainly of water

Water is not only plentiful, it is also Water is not only plentiful, it is also always on the movealways on the move

It moves in and out of our bodiesIt moves in and out of our bodies It flows from ice cubes melting in a It flows from ice cubes melting in a

drinking glassdrinking glass It evaporates into the air from wet It evaporates into the air from wet

clothes or from oceans, lakes or riversclothes or from oceans, lakes or rivers Evaporation explains why puddles Evaporation explains why puddles

disappears and streets dry out after a disappears and streets dry out after a rain showerrain shower

Water also falls from clouds as Water also falls from clouds as different types of precipitationdifferent types of precipitation

Examples: rain, snowExamples: rain, snow The best way to understand the The best way to understand the

Earth’s water supply is to study it as Earth’s water supply is to study it as a systema system Water constantly moves around Water constantly moves around

between the sea, sky, land, and lifebetween the sea, sky, land, and life

Water CycleWater Cycle

The water cycle is the process in The water cycle is the process in which nearly all water on Earth which nearly all water on Earth moves continuously between the moves continuously between the oceans, land, and atmosphereoceans, land, and atmosphere

Liquid water is transformed into Liquid water is transformed into water vapour by evaporation, and water vapour by evaporation, and water vapour is transformed into water vapour is transformed into liquid water by condensationliquid water by condensation

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Water is truly a remarkable substance. It is Water is truly a remarkable substance. It is the only substance that is found abundantly the only substance that is found abundantly in all three states on the earth’s surface. in all three states on the earth’s surface.

Many of its unusual properties are produced Many of its unusual properties are produced by strong hydrogen bonds that cause water by strong hydrogen bonds that cause water molecules to “stick” to each other and to molecules to “stick” to each other and to “stick” to many other compounds. “stick” to many other compounds.

What most of us consider normal behaviour What most of us consider normal behaviour for water is most unusual for nearly all for water is most unusual for nearly all other substances. other substances.

Note:Note: If a molecule of water were the size If a molecule of water were the size of a baseball; a drop of water would be the of a baseball; a drop of water would be the size of the earth! WOW!size of the earth! WOW!

Other amazing properties:Other amazing properties: Water has an unusually high freezing point Water has an unusually high freezing point

and boiling point for its molecular mass. and boiling point for its molecular mass. Water is a liquid at room temperature, Water is a liquid at room temperature, where similar compounds are gaseous.where similar compounds are gaseous.

Water has the highest heat capacity of all Water has the highest heat capacity of all substances. Water can absorb tremendous substances. Water can absorb tremendous amounts of heat without raising its own amounts of heat without raising its own temperature very much. In contrast, sand temperature very much. In contrast, sand has a very low heat capacity.has a very low heat capacity.

Water is known as the universal solvent Water is known as the universal solvent because it can dissolve large quantities because it can dissolve large quantities of many different kinds of substances.of many different kinds of substances.

Water has the highest surface tension Water has the highest surface tension of all liquids.of all liquids.

Pure water has its maximum density at Pure water has its maximum density at 44°°C.C.

Nearly all substances contract when Nearly all substances contract when they freeze; water expands 9% when it they freeze; water expands 9% when it changes from water to ice.changes from water to ice.

Except for ammonia, water has the Except for ammonia, water has the highest latent heat of fusion (melting highest latent heat of fusion (melting or freezing).or freezing).

Water has the highest latent heat of Water has the highest latent heat of evaporation.evaporation.

Water has a low viscosity (it flows Water has a low viscosity (it flows easily). In contrast, cold molasses is easily). In contrast, cold molasses is very viscous.very viscous.

Water is very transparent for a liquid.Water is very transparent for a liquid.

QUESTIONS QUESTIONS

If water froze like other liquids, how If water froze like other liquids, how would this affect:would this affect:

skating on a pond?skating on a pond? Plants and animals living in a lake Plants and animals living in a lake

during the summer?during the summer? Glaciers are often called “river of ice” Glaciers are often called “river of ice”

because compressed blocks of snow because compressed blocks of snow flows down the solid glacial ice. Why flows down the solid glacial ice. Why do glaciers flow?do glaciers flow?

Why is the temperature of the water Why is the temperature of the water near the bottom of a very deep, ice-near the bottom of a very deep, ice-covered lake as warm as 4˚C?covered lake as warm as 4˚C?

Many small aquatic insects are able Many small aquatic insects are able to walk on water. How?to walk on water. How?

The temperature of inland regions The temperature of inland regions fluctuates greatly from day to night, fluctuates greatly from day to night, but the temperature stays about the but the temperature stays about the same in coastal regions. Why?same in coastal regions. Why?

On a very hot summer day, the sand On a very hot summer day, the sand at the beach feels very hot on your at the beach feels very hot on your bare feet, while shallow pools feel bare feet, while shallow pools feel much cooler. Why?much cooler. Why?

Power outages in the winter often Power outages in the winter often results in many homes having results in many homes having ruptured water pipes. Why?ruptured water pipes. Why?

Seawater contains almost every Seawater contains almost every element or chemical found on earth. element or chemical found on earth. Why?Why?

Some major ocean surface currents Some major ocean surface currents can attain a speed of 5 knots (almost can attain a speed of 5 knots (almost 10km/hr). In what ways do these 10km/hr). In what ways do these major currents affect our lives on a major currents affect our lives on a daily basis?daily basis?