Water Chapter 11. Properties of Water Polar molecule Cohesion and adhesion High specific heat Density greatest at 4 o C Universal solvent of life

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10/15/2014 10/15/2014 Vasser vapor sound exp.

WaterSmart 10/15/2014 Water Chapter 11 DO NOT COPY 1. Draw a picture of a water molecule. 2.

Properties of Water Polar molecule Cohesion and adhesion High specific heat Density greatest at 4 o C Universal

1 10/15/ /15/2014 Vasser vapor sound exp. Drink raw sewage 80 s Density CH3OH Groundwater A²=A+D+ ( )+1 1=U Chemical Prop. Mol.Struct. WaterSmart 10/15/2014 Water Chapter 11 DO NOT COPY 1. Draw a picture of a water molecule. 2. Is water polar or nonpolar? Properties of Water Polar molecule Cohesion and adhesion High specific heat Density greatest at 4 o C Universal solvent of life Polarity of Water In a water molecule two hydrogen atoms form bonds with an oxygen atom. This gives water a positive side and a negative side like a magnet. the part around oxygen has a partial negative charge. The part near the two hydrogen atoms has a partial positive charge. 1

Polarity of Water We say water is a POLAR molecule because it has a

against gravity. It helps move chemicals around inside your body.

2 Polarity of Water We say water is a POLAR molecule because it has a positive pole and a negative pole (like north and south poles) Oil is NOT polar. Living things Depend on Water s stickiness In plants, water can move against gravity. It helps move chemicals around inside your body. Water has a high Surface tension Water behaves as if covered by an invisible film. Some animals can stand, walk, or run on water without breaking the surface! Water resists changes in temperature So, water can absorb lots of heat without getting hot. It acts like a heat sponge. 2

3 Degrees Celsius at Sea Level 100 o C Water boils 37 o C Human body temperature 23 o C Room temperature Resists changes in temperature Takes a lot of heat to turn it into a vapor 0 o C Water freezes What does altitude have to do with boiling & freezing? The higher you are, the lower the air pressure is, so water molecules want to fly around. They boil easier. Resists changes in temperature Takes a lot of heat to turn it into a vapor Expands when it freezes So, ice floats! Resists changes in temperature Takes a lot of heat to turn it into a vapor Expands when it freezes Lots of things can dissolve in it Chapter 11, page 362 Chapter 11, page % of Earth s water is salt 3

Chapter 11, page 362 2. 97% of Earth s water is salt 3.

4. Your body is 2/3 Page 365 The Water Cycle: page 365

the salt is left behind (making fresh water vapor). 4

4 Chapter 11, page % of Earth s water is salt 3. 70% of freshwater is frozen. Chapter 11, page % of Earth s water is salt 3. 70% of freshwater is frozen. 4. Your body is 2/3 Page 365 The Water Cycle: page 365 The Water Cycle: page 365 When salt water evaporates, the salt is left behind (making fresh water vapor). 4

3. Precipitation: When enough water molecules stick together, they fall to the ground. 3.

the amount of heat that must be absorbed or lost for one gram of a substance to change its

Three-fourths of the earth is covered by The water serves as a large heat sink responsible for: 1.

evaporates This is responsible for: Moderating earth s climate Stabilizes temperature in aquatic

until 4 o C Expands from 4 o C to 0 o C The density of water: 1.

5 The Water Cycle: page Condensation: As air cools, water molecules slow down and stick together. The Water Cycle: page Condensation: As air cools, water molecules slow down and stick together. 3. Precipitation: When enough water molecules stick together, they fall to the ground. The Water Cycle: page Condensation: As air cools, water molecules slow down and stick together. 3. Precipitation: When enough water molecules stick together, they fall to the ground Specific Heat is the amount of heat that must be absorbed or lost for one gram of a substance to change its temperature by 1 o C. Three-fourths of the earth is covered by The water serves as a large heat sink responsible for: 1. Prevention of temperature fluctuations that are outside the range suitable for life. 2. Coastal areas having a mild climate 3. A stable marine environment Evaporative Cooling The cooling of a surface occurs when the liquid evaporates This is responsible for: Moderating earth s climate Stabilizes temperature in aquatic ecosystems Preventing organisms from overheating Density of Water Most dense at 4 o C Contracts until 4 o C Expands from 4 o C to 0 o C The density of water: 1. Prevents water from freezing from the bottom up. 2. Ice forms on the surface first the freezing of the water releases heat to the water below creating insulation. 3. Makes transition between season less abrupt. 5

Ice is about 10% less dense than water at 4 o C. EPISODE 3: Water Density & Dog Biscuits Fig. 3.5 Copyright 2002 Pearson Education, Inc.

6 The Really Bad 80 s Science Show! I hate children This dog biscuit is crunchy When water reaches 0 o C, water becomes locked into a crystalline lattice with each molecule bonded to to the maximum of four partners. As ice starts to melt, some of the hydrogen bonds break and some water molecules can slip closer together than they can while in the ice state. Ice is about 10% less dense than water at 4 o C. EPISODE 3: Water Density & Dog Biscuits Fig. 3.5 Copyright 2002 Pearson Education, Inc., publishing as Benjamin Cummings Solvent for Life Many chemicals can dissolve in Chemistry of life happens in Which is heavier, a bucket of water or a bucket of ice? Every question is ALWAYS followed by another: Why? Water expands as it freezes. So, there is more space between molecules of ice. HEAVIER If you melted the bucket of ice, would be bucket still be full? 6

Properties of Water. Polar molecule Cohesion and adhesion High specific heat Density greatest at 4 o C Universal solvent of life

Properties of Water. Polar molecule Cohesion and adhesion High specific heat Density greatest at 4 o C Universal solvent of life Properties of Water Polar molecule Cohesion and adhesion High specific heat Density greatest at 4 o C Universal solvent of life Polarity of Water In a water molecule two hydrogen atoms form single polar