Chapter 8 Solutions

1. Chapter 8Solutions Properties of Water Solutions LecturePLUS Timberlake

2. Predict the % water in the following foods LecturePLUS Timberlake

3. Predict the % water in the following foods 88% water 94% water 85% water 86% water LecturePLUS Timberlake

4. Water in the Body water gain water loss liquids 1000 mL urine 1500 mL food 1200 mL perspiring 300 mL cells 300 mL exhaling 600 mL feces 100 mL Calculate the total water gain and water loss Total ______ mL _____ mL LecturePLUS Timberlake

5. Water • Most common solvent • A polar molecule O- a hydrogen bond H + H + LecturePLUS Timberlake

6. Hydrogen Bonds Attract Polar Water Molecules LecturePLUS Timberlake

7. Explore:Surface Tension • Fill a glass to the brim with water • How many pennies can you add to the glass without causing any water to run over? Predict _________________ Actual _________________ • Explain your results LecturePLUS Timberlake

8. Explore 1. Place some water on a waxy surface. Why do drops form? 2. Carefully place a needle on the surface of water. Why does it float? What happens if you push it through the water surface? 3. Sprinkle pepper on water. What does it do? Add a drop of soap. What happens? LecturePLUS Timberlake

9. Surface Tension • Water molecules within water hydrogen bond in all directions • Water molecules at surface cannot hydrogen bond above the surface, pulled inward • Water surface behaves like a thin, elastic membrane or “skin” • Surfactants (detergents) undo hydrogen bonding LecturePLUS Timberlake

10. Solute and Solvent Solutions are homogeneous mixtures of two or more substances • Solute The substance in the lesser amount • Solvent The substance in the greater amount LecturePLUS Timberlake

11. Nature of Solutes in Solutions • Spread evenly throughout the solution • Cannot be separated by filtration • Can be separated by evaporation • Not visible, solution appears transparent • May give a color to the solution LecturePLUS Timberlake

12. Types of Solutions air O2 gas and N2 gas gas/gas soda CO2 gas in water gas/liquid seawater NaCl in water solid/liquid brass copper and zinc solid/solid LecturePLUS Timberlake

13. Discussion Give examples of some solutions and explain why they are solutions. LecturePLUS Timberlake

14. Learning Check SF1 (1) element (2) compound (3) solution A. water 1 2 3 B. sugar 1 2 3 C. salt water 1 2 3 D. air 1 2 3 E. tea 1 2 3 LecturePLUS Timberlake

15. Solution SF1 (1) element (2) compound (3) solution A. water 2 B. sugar 2 C. salt water 3 D. air 3 E. tea 3 LecturePLUS Timberlake

16. Learning Check SF2 Identify the solute and the solvent. A. brass: 20 g zinc + 50 g copper solute = 1) zinc 2) copper solvent = 1) zinc 2) copper B. 100 g H2O+5 g KCl solute = 1) KCl 2) H2O solvent = 1) KCl 2) H2O LecturePLUS Timberlake

17. Solution SF2 A. brass: 20 g zinc + 50 g copper solute = 1) zinc solvent = 2) copper B. 100 g H2O+5 g KCl solute = 1) KCl solvent = 2) H2O LecturePLUS Timberlake

18. Learning Check SF3 Identify the solute in each of the following solutions: A. 2 g sugar (1) + 100 mL water (2) B. 60.0 mL ethyl alcohol(1) and 30.0 mL of methyl alcohol (2) C. 55.0 mL water (1) and 1.50 g NaCl (2) D. Air: 200 mL O2(1) + 800 mL N2 (2) LecturePLUS Timberlake

19. Solution SF3 Identify the solute in each of the following solutions: A. 2 g sugar (1) B. 30.0 mL of methyl alcohol (2) C. 50 g NaCl (2) D. 200 mL O2 (1) LecturePLUS Timberlake

20. Like dissolves like A ____________ solvent such as water is needed to dissolve polar solutes such as sugar and ionic solutes such as NaCl. A ___________solvent such as hexane (C6H14) is needed to dissolve nonpolar solutes such as oil or grease. LecturePLUS Timberlake

21. Learning Check SF4 Which of the following solutes will dissolve in water? Why? 1) Na2SO4 2) gasoline 3) I2 4) HCl LecturePLUS Timberlake

22. Solution SF4 Which of the following solutes will dissolve in water? Why? 1) Na2SO4 Yes, polar (ionic) 2) gasoline No, nonnpolar 3) I2 No, nonpolar 4) HCl Yes, Polar LecturePLUS Timberlake

23. Formation of a Solution H2O Hydration Na+ Cl- Na+ Dissolved solute Cl- H2O Na+ Cl- solute LecturePLUS Timberlake

24. Writing An Equation for a Solution When NaCl(s) dissolves in water, the reaction can be written as H2O NaCl(s) Na+ (aq) + Cl- (aq) solid separation of ions in water LecturePLUS Timberlake

25. Learning Check SF5 Solid LiCl is added to some water. It dissolves because A. The Li+ ions are attracted to the 1) oxygen atom(-) of water 2) hydrogen atom(+) of water B. The Cl- ions are attracted to the 1) oxygen atom(-) of water 2) hydrogen atom(+) of water LecturePLUS Timberlake

26. Solution SF5 Solid LiCl is added to some water. It dissolves because A. The Li+ ions are attracted to the 1) oxygen atom(-) of water B. The Cl- ions are attracted to the 2) hydrogen atom(+) of water LecturePLUS Timberlake

27. Rate of Solution You are making a chicken broth using a bouillon cube. What are some things you can do to make it dissolve faster? • Crush it • Use hot water (increase temperature) • Stir it LecturePLUS Timberlake

28. Learning Check SF6 You need to dissolve some gelatin in water. Indicate the effect of each of the following on the rate at which the gelatin dissolves as (1) increase, (2) decrease, (3) no change A. ___Heating the water B. ___Using large pieces of gelatin C. ___Stirring the solution LecturePLUS Timberlake

29. Learning Check SF6 You need to dissolve some gelatin in water. Indicate the effect of each of the following on the rate at which the gelatin dissolves as (1) increase, (2) decrease, (3) no change A. 1 Heating the water B. 2 Using large pieces of gelatin C. 2 Stirring the solution LecturePLUS Timberlake