water slides
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Notes on 'Water'TRANSCRIPT
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