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CHAPTER 3 Water and the Fitness of the Environment.

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Presentation on theme: "CHAPTER 3 Water and the Fitness of the Environment."— Presentation transcript:

1 CHAPTER 3 Water and the Fitness of the Environment

2 PROPERTIES OF WATER The most common substance on Earth. The basis of life. It exists in all three forms of matter: solid, liquid, and gas. The most common substance on Earth. The basis of life. It exists in all three forms of matter: solid, liquid, and gas.

3 WATER

4 PROPERTIES OF WATER It has a high heat capacity = can absorb large amounts of heat. It is less dense in the solid form (ice) than in the liquid form, due to ice crystals. Water has a pH of 7 (neutral). Cohesion Adhesion It has a high heat capacity = can absorb large amounts of heat. It is less dense in the solid form (ice) than in the liquid form, due to ice crystals. Water has a pH of 7 (neutral). Cohesion Adhesion

5 COHESION Cohesion = an attraction between substances of the same kind. –Surface Tension of Water Due to Hydrogen bonding Adhesion = an attraction between different substances. –Capillary Action in plants Cohesion = an attraction between substances of the same kind. –Surface Tension of Water Due to Hydrogen bonding Adhesion = an attraction between different substances. –Capillary Action in plants

6 SURFACE TENSION It is a measure of the strength of waters surface. Water is sticky and elastic. It clumps together. It has a skin. It has a HIGH surface tension. Water and wax paper. Water striders. It is a measure of the strength of waters surface. Water is sticky and elastic. It clumps together. It has a skin. It has a HIGH surface tension. Water and wax paper. Water striders.

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8 CAPILLARY ACTION Process by which water moves up through the roots of plants. It is possible because of adhesion and cohesion. Process by which water moves up through the roots of plants. It is possible because of adhesion and cohesion.

9 GREEN BASILISK LIZARD Jesus Christ Lizard enlarge/basilisk-lizard_image.html Jesus Christ Lizard enlarge/basilisk-lizard_image.html

10 HIGH HEAT CAPACITY

11 TEMPERATURE MODERATION Water absorbs heat from warmer air and release heat to cooler air. Only little variation in its own temperature. Kinetic energy = energy of motion Water absorbs heat from warmer air and release heat to cooler air. Only little variation in its own temperature. Kinetic energy = energy of motion Heat vs. Temperature Water has a high specific heat = –1 cal/g/ o C High heat of evaporation. –Evaporative cooling Sweating What happens when it is hot and humid outside? Heat vs. Temperature Water has a high specific heat = –1 cal/g/ o C High heat of evaporation. –Evaporative cooling Sweating What happens when it is hot and humid outside?

12 WATERS EXPANSION Less dense as a solid than a liquid. Due to hydrogen bonding: –Not enough kinetic energy to break hydrogen bonds –Crystal lattice structure = each water molecules bonded to 4 other. Less dense as a solid than a liquid. Due to hydrogen bonding: –Not enough kinetic energy to break hydrogen bonds –Crystal lattice structure = each water molecules bonded to 4 other. Ice floats = crystal structure has holes and takes up space –Ice has less molecules than the same volume of liquid water. –Less dense Floating ice protects water below from cooler air = insulating blanket. Ice floats = crystal structure has holes and takes up space –Ice has less molecules than the same volume of liquid water. –Less dense Floating ice protects water below from cooler air = insulating blanket.

13 THE SOLVENT OF LIFE Solution = A homogeneous mixture of two or more substances. Solvent Solute Aqueous solution Ionic compounds and polar molecules dissolve well in water. Solution = A homogeneous mixture of two or more substances. Solvent Solute Aqueous solution Ionic compounds and polar molecules dissolve well in water. Non-polar molecules do NOT dissolve well in water. –OIL and Water Hydrophilic & Hydrophobic Colloid Non-polar molecules do NOT dissolve well in water. –OIL and Water Hydrophilic & Hydrophobic Colloid

14 WHICH PROPERTY OF WATER CAN YOU RECOGNIZE IN THE PICTURES?

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24 ACIDS AND BASES Acids = Compounds that form hydrogen ions (H+) when dissolved in water. Bases = Compounds that reduce the amount of hydrogen ions (H+) in a solution. pH scale = based on the concentration of hydrogen ions in a solution. Acids = Compounds that form hydrogen ions (H+) when dissolved in water. Bases = Compounds that reduce the amount of hydrogen ions (H+) in a solution. pH scale = based on the concentration of hydrogen ions in a solution.

25 WATER STRIDER Look at the water strider in the pictures and answer the following question: –Imagine you are the first human being to discover this creature. How would you explain to the scientific community how this insect is able to walk on water? Look at the water strider in the pictures and answer the following question: –Imagine you are the first human being to discover this creature. How would you explain to the scientific community how this insect is able to walk on water?

26 QUESTIONS Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability to sweat to lower body temperature? –A. The release of heat by the formation of hydrogen bonds. –B. The absorption of heat by the breaking of hydrogen bonds. –C. Waters high surface tension. Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability to sweat to lower body temperature? –A. The release of heat by the formation of hydrogen bonds. –B. The absorption of heat by the breaking of hydrogen bonds. –C. Waters high surface tension.

27 QUESTIONS How does electronegativity affect interactions between water molecules? Can water molecules bond like this? Explain. How does electronegativity affect interactions between water molecules? Can water molecules bond like this? Explain. H O H H H O

28 QUESTIONS The bonds that are broken when water vaporizes are: –A. ionic bonds –B. polar covalent bonds. –C. nonpolar covalent bonds. The bonds that are broken when water vaporizes are: –A. ionic bonds –B. polar covalent bonds. –C. nonpolar covalent bonds.

29 QUESTIONS Which of the following is an example of a hydrophobic material? –A. Paper –B. Table salt –C. Wax –D. Sugar –E. Pasta Which of the following is an example of a hydrophobic material? –A. Paper –B. Table salt –C. Wax –D. Sugar –E. Pasta

30 QUESTIONS Describe how the properties of water aid in capillary action? Explain the phrase: The heat doesnt bother me; its the HUMIDITY that does! Describe how the properties of water aid in capillary action? Explain the phrase: The heat doesnt bother me; its the HUMIDITY that does!


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