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Slide 1 of 23 15.1 Chemistry. © Copyright Pearson Prentice Hall Slide 2 of 23 Water and Its Properties Water covers about three quarters of Earths surface.

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Presentation on theme: "Slide 1 of 23 15.1 Chemistry. © Copyright Pearson Prentice Hall Slide 2 of 23 Water and Its Properties Water covers about three quarters of Earths surface."— Presentation transcript:

1 Slide 1 of Chemistry

2 © Copyright Pearson Prentice Hall Slide 2 of 23 Water and Its Properties Water covers about three quarters of Earths surface. All life forms that are known to exist are made mostly of water. You will learn about the properties of water and what makes this unique substance essential to life on Earth. 15.1

3 © Copyright Pearson Prentice Hall Water and Its Properties > Slide 3 of Water in the Liquid State How can you account for the high surface tension and low vapor pressure of water?

4 Slide 4 of 23 © Copyright Pearson Prentice Hall Water and Its Properties > Water in the Liquid State You could not live without water, nor could all the plants and animals on Earth. 15.1

5 Slide 5 of 23 © Copyright Pearson Prentice Hall Water and Its Properties > Water in the Liquid State A water molecule is polar. 15.1

6 © Copyright Pearson Prentice Hall Slide 6 of 23 Water and Its Properties > Water in the Liquid State Animation 19 See how hydrogen bonding results in the unique properties of water.

7 Slide 7 of 23 © Copyright Pearson Prentice Hall Water and Its Properties > Water in the Liquid State Polar molecules are attracted to one another by dipole interactions. The negative end of one molecule attracts the positive end of another molecule. 15.1

8 Slide 8 of 23 © Copyright Pearson Prentice Hall Water and Its Properties > Water in the Liquid State The intermolecular attraction among water molecules results in the formation of hydrogen bonds. 15.1

9 © Copyright Pearson Prentice Hall Slide 9 of 23 Water and Its Properties > Water in the Liquid State Many unique and important properties of waterincluding its high surface tension and low vapor pressureresult from hydrogen bonding. 15.1

10 Slide 10 of 23 © Copyright Pearson Prentice Hall Water and Its Properties > Water in the Liquid State Surface Tension The inward force, or pull, that tends to minimize the surface area of a liquid is called surface tension. All liquids have a surface tension, but waters surface tension is higher than most. 15.1

11 Slide 11 of 23 © Copyright Pearson Prentice Hall Water and Its Properties > Water in the Liquid State Surface tension makes it possible for this water strider to walk on water. 15.1

12 Slide 12 of 23 © Copyright Pearson Prentice Hall Water and Its Properties > Water in the Liquid State A surfactant is any substance that interferes with the hydrogen bonding between water molecules and thereby reduces surface tension. 15.1

13 Slide 13 of 23 © Copyright Pearson Prentice Hall Water and Its Properties > Water in the Liquid State Vapor Pressure Hydrogen bonding between water molecules also explains waters unusually low vapor pressure. Because hydrogen bonds hold water molecules to one another, the tendency of these molecules to escape is low, and evaporation is slow. 15.1

14 © Copyright Pearson Prentice Hall Slide 14 of 23 Water and Its Properties > Water in the Liquid State Animation 20 Discover how some insects can walk on water.

15 © Copyright Pearson Prentice Hall Water and Its Properties > Slide 15 of 23 Water in the Solid State How would you describe the structure of ice? 15.1

16 Slide 16 of 23 © Copyright Pearson Prentice Hall Water and Its Properties > Water in the Solid State As water begins to cool, it behaves initially like a typical liquid. It contracts slightly and its density gradually increases. When the temperature of the water falls below 4˚C, the density of water starts to decrease. 15.1

17 Slide 17 of 23 © Copyright Pearson Prentice Hall Water and Its Properties > Water in the Solid State 15.1

18 Slide 18 of 23 © Copyright Pearson Prentice Hall Water and Its Properties > Water in the Solid State Hydrogen bonds hold the water molecules in place in the solid phase. 15.1

19 Slide 19 of 23 © Copyright Pearson Prentice Hall Water and Its Properties > Water in the Solid State The structure of ice is a regular open framework of water molecules arranged like a honeycomb. When ice melts, the framework collapses, and the water molecules pack closer together, making liquid water more dense than ice. 15.1

20 © Copyright Pearson Prentice Hall Slide 20 of 23 Section Quiz -or- Continue to: Launch: Assess students understanding of the concepts in Section 15.1 Section Quiz

21 © Copyright Pearson Prentice Hall Slide 21 of 23 1.Many of the unusual properties of water are the result of a.hydrogen bonding. b.nonpolar molecules. c.low molar mass. d.dispersion forces Section Quiz.

22 © Copyright Pearson Prentice Hall Slide 22 of 23 2.A surfactant causes water to spread out over a surface. This spreading occurs because the surfactant a.attaches to the surface. b.interferes with hydrogen bonding. c.lowers the vapor pressure. d.lowers the density of water Section Quiz.

23 © Copyright Pearson Prentice Hall Slide 23 of 23 3.Ice is less dense than liquid water because in ice the water molecules a.expand because of weakened covalent bonds. b.have a regular open honeycomb framework. c.expand because of weakened hydrogen bonds. d.have a more disorderly arrangement with lower density Section Quiz.

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