PS 0266 SCIENCE IPS 0266 SCIENCE I

WEEK 3WEEK 3

WATERWATER

Quotes of the Day Quotes of the Day

"We wait all these years to find someone "We wait all these years to find someone who understands us, I thought, someone who understands us, I thought, someone who accepts us as we are, someone with a who accepts us as we are, someone with a wizard's power to melt stone to sunlight, wizard's power to melt stone to sunlight, who can bring us happiness in spite of who can bring us happiness in spite of trials, who can face our dragons in the trials, who can face our dragons in the night, who can transform us into the soul night, who can transform us into the soul we choose to be. Just yesterday I found we choose to be. Just yesterday I found that magical Someone is the face we see that magical Someone is the face we see in the mirror: It's us and our homemade in the mirror: It's us and our homemade masks." masks." Richard Bach Richard Bach

Objectives Objectives

State the properties of water State the properties of water chemically and physicallychemically and physically

Identify the states of waterIdentify the states of water Define the term ‘evaporation’, Define the term ‘evaporation’,

‘boiling’, ‘condensation’, ‘freezing’ & ‘boiling’, ‘condensation’, ‘freezing’ & meltingmelting

Draw a water cycleDraw a water cycle Identify the factors that affect the Identify the factors that affect the

amount of solid dissolves in water as amount of solid dissolves in water as a solventa solvent

Overview of today’s lecture Overview of today’s lecture

Properties of waterProperties of water Water’s Physical Properties Water’s Physical Properties Water on and in the EarthWater on and in the Earth The states of water The states of water Changes in states of waterChanges in states of water The water cycle The water cycle Water as a solventWater as a solvent Soft water & Hard water Soft water & Hard water

Properties of WaterProperties of Water

Pure water is virtually colourless, Pure water is virtually colourless, tasteless and it has no smell. tasteless and it has no smell.

Water’s chemical description is H2O.Water’s chemical description is H2O. One atom of oxygen bound to two One atom of oxygen bound to two

atoms of hydrogen. atoms of hydrogen.

Properties of WaterProperties of Water

The hydrogen atoms are “attached” The hydrogen atoms are “attached” to one side of the oxygen atom. to one side of the oxygen atom.

Resulting in a water molecule having Resulting in a water molecule having a positive charge on the side where a positive charge on the side where the hydrogen atoms are negatively the hydrogen atoms are negatively charged on the other side. charged on the other side.

Water molecules tend to attract each Water molecules tend to attract each other, making it kind of “sticky”. other, making it kind of “sticky”.

Properties of WaterProperties of Water

All these water molecules attracting each All these water molecules attracting each other mean they tend to clump together. other mean they tend to clump together.

This is why water drops are,This is why water drops are, in fact, drops!in fact, drops! Water’s original shapeWater’s original shape is a perfect sphere but due is a perfect sphere but due to gravity, it looks like a tear to gravity, it looks like a tear when it drops.when it drops.Pure water has a neutral pH of 7.Pure water has a neutral pH of 7.

Water’s Physical PropertiesWater’s Physical Properties

Water is unique, it is the only natural Water is unique, it is the only natural substance that is found in all 3 substance that is found in all 3 states: liquid, solid and gas. states: liquid, solid and gas.

Earth’s water is constantly Earth’s water is constantly interacting, changing and in interacting, changing and in movement. movement.

Water freezes at 32° Fahrenheit (F) Water freezes at 32° Fahrenheit (F) and boils at 212 ° F (at sea level, but and boils at 212 ° F (at sea level, but 186.4° at 14,000 feet). 186.4° at 14,000 feet).

Water’s Physical PropertiesWater’s Physical Properties

Water is unusual in that the solid Water is unusual in that the solid form, ice, is less dense than the form, ice, is less dense than the liquid form, which is why ice floats. liquid form, which is why ice floats.

Water has a high specific heat index. Water has a high specific heat index. The high specific heat index of water The high specific heat index of water

also helps regulate the rate at which also helps regulate the rate at which air changes temperature.air changes temperature.

Water has a very high surface Water has a very high surface tension. tension.

Water on and in the EarthWater on and in the Earth

(http://ga.water.sgs.gov/edu/earthwherewater.html)

How much of Earth’s water is How much of Earth’s water is usable by humans?usable by humans?

The Three States of WaterThe Three States of Water

The water that comes out of our taps is a The water that comes out of our taps is a liquid. We say it is water in the liquid liquid. We say it is water in the liquid state. state.

If we put water in a freezer, it changes to If we put water in a freezer, it changes to ice. Ice is a solid. Ice is water in the solid ice. Ice is a solid. Ice is water in the solid state. state.

If we boil water for a long time, it If we boil water for a long time, it disappears. It changes to steam. Steam is disappears. It changes to steam. Steam is a gas. Steam is water in the gaseous state. a gas. Steam is water in the gaseous state.

Changes in States of WaterChanges in States of Water

When heated, water gains heat. When When heated, water gains heat. When cooled, water loses heat. cooled, water loses heat.

Heat energy can change water from one Heat energy can change water from one state to another. These changes are state to another. These changes are called: called:

Freezing.Freezing. Melting,Melting, Boiling,Boiling, Evaporation, andEvaporation, and Condensation. Condensation.

Freezing Freezing

When water becomes cold, it loses When water becomes cold, it loses heat. It changes from the liquid state heat. It changes from the liquid state to the solid state. At 0°C , water to the solid state. At 0°C , water changes to ice. changes to ice.

Melting Melting

When water changes from solid to When water changes from solid to liquid, we say it is melting. Ice melts liquid, we say it is melting. Ice melts at 0°C at 0°C

BoilingBoiling

When we heat water, it becomes hot. When we heat water, it becomes hot. It will start to boil at 100°C. At this It will start to boil at 100°C. At this temperature, water bubbles and temperature, water bubbles and changes to steam. Steam is a gas. changes to steam. Steam is a gas.

EvaporationEvaporation

Water does not have to boil to Water does not have to boil to change into a gas.change into a gas.

This change can happen at any time This change can happen at any time and at any temperature. and at any temperature.

Condensation Condensation

When water vapour in the air touches When water vapour in the air touches something cold, it changes into liquid something cold, it changes into liquid water. water.

It also happens when water boils. It also happens when water boils. When steam touches cold air, we can When steam touches cold air, we can see a cloud, made up of tiny drops of see a cloud, made up of tiny drops of water. water.

Changes in States of WaterChanges in States of Water

The Water Cycle The Water Cycle

Water as a SolventWater as a Solvent

When sugar is put into the water, it When sugar is put into the water, it dissolves. dissolves.

When sugar dissolves in water, we When sugar dissolves in water, we get a solution. get a solution.

Things dissolve in water are soluble. Things dissolve in water are soluble. Water is a universal solvent. Water is a universal solvent. Things that are not dissolved in Things that are not dissolved in

water are insoluble. water are insoluble. Gases also dissolved in water. Gases also dissolved in water.

Water as a SolventWater as a Solvent

More solid dissolves with: More solid dissolves with:

1)1) More water andMore water and

2)2) At a higher temperature. At a higher temperature.

Soft Water & Hard WaterSoft Water & Hard Water

Soft water is the term used to Soft water is the term used to describe types of water that contain describe types of water that contain few or no calcium or magnesium few or no calcium or magnesium ions.ions.

Usually comes from peat or igneous Usually comes from peat or igneous rock sources such as granite or rock sources such as granite or sandstone. sandstone.

Hard WaterHard Water

Has a high mineral content. Has a high mineral content. Usually consists of high levels of metal Usually consists of high levels of metal

ions such as Ca and Mg in the form of ions such as Ca and Mg in the form of carbonates or bicarbonates or sulfates. carbonates or bicarbonates or sulfates.

To determine if water is hard or soft, use To determine if water is hard or soft, use the lather/froth test. the lather/froth test.

If the water is very soft, soap will tend to If the water is very soft, soap will tend to lather up easily when agitated. lather up easily when agitated.

Toothpaste will also not froth well in hard Toothpaste will also not froth well in hard water. water.

RecapRecap

Properties of waterProperties of water

Water’s Physical PropertiesWater’s Physical Properties

Water on and in the EarthWater on and in the Earth

The States of WaterThe States of Water

Changes in States of WaterChanges in States of Water

RecapRecap

The Water Cycle The Water Cycle

Water as a SolventWater as a Solvent

Soft Water & Hard WaterSoft Water & Hard Water

Next Week…Next Week…

Week 7 Magnets Week 7 Magnets

The End The End