WATER PROPERTIES. Supplemental Textbook Material Ch. 16, p

Transcription

1 WATER PROPERTIES Supplemental Textbook Material Ch. 16, p

2 Be sure to attend lab this week Bring the lab manual Must pass lab to pass this class Instructors will give percent lab grade to one another

3 Covalent Bonds Need octet of electrons surrounding element in the dot diagram Some bonds are multiple, stronger!

4 Covalent Bond Chlorine Gas Covalent bond Draw dot diagram for each atom Bond using all electrons Octet around each Show bonding pair with a line

5 Octet Rule for Oxygen Start with dot diagram Don t have octets of electrons Share two pairs to get to eight for each atom Indicate with double bar

6 Naming Compounds Find subscripts to indicate how many of each atom in the molecule Use chart at right for number of each

7 Polar molecules

8 Electro-negativity

9 Poly-atomic ions Covalently bonded compounds Not electrically neutral Maintain covalent bonds within ions as they interact with other ions to form ionic compounds Those bonded to oxygen become ate

10 Common poly-atomic ions Hydroxide OH - Bicarbonate HCO - 3 Carbonate CO 2-3 Sulfate SO 2-4 Nitrate NO - 3 Phosphate PO 3-4 Chromate CrO 2-4

11 Chemical Formulas Molecule has specific ratio of elements Subscripts how many Parentheses how many sets Coefficients how many molecules in reaction

12 Chemical Formulas H 2 SO 4 Ca 3 (PO 4 ) 2 Na 2 O + CaCl 2 CaO + 2 NaCl MgBr 2 + 2Ag(NO 3 ) Mg(NO 3 ) 2 + 2AgBr

13 Predict Molecule Shape Draw molecule dot diagram Put most electronegative element in the center of molecule

14 Electro-negativity

15 Predict Molecule Shape Draw molecule dot diagram Put most electronegative element in the center of molecule Arrange other atoms around it Include all unbonded pairs and bonds, so that each atom has octet of electrons Choose tentative shape from number of atoms plus unbonded pairs

16 Predict Molecule Shape Choose tentative shape from number of atoms plus unbonded pairs Erase unbonded pairs Adjust shape to account for the empty spots Tetrahedrons may become pyramids 3-d shapes may become bent

17 Geometry of Molecules

18 Typical Shapes of Molecules

19 Tetrahedral molecules

20 Pyramidal molecules

21 Bent molecules

22 Polar molecules

23 Dipole attraction in solid and liquid

24 Dissolution of ionic substance

25 Solute/Solvent

26 Water phases and molecules

27 Bent Water Molecule Covalent bonds Polar Dissolves ionic substances

28 Properties of Water Solid water floats on liquid water High specific heat High heat of vaporization Universal solvent

29 Distribution/Cycle Animation

30 Hydrologic Cycle

31 Natural substances in water

32 Impurities in Runoff Atmosphere Dissolved substances Silt, etc. Radon

33 Organic byproducts in water

34 Contamination of Water Micro-organisms Decay products Plant nutrients Petroleum compounds Acid Industry Mining

35 Drinking water standards

36 Be sure to attend lab this week Bring the lab manual Must pass lab to pass this class Instructors will give percent lab grade to one another

37 Heat and Energy Transfer Supplementary Textbook Material Chapter 18: p Review Questions: 2-4, 21-26

38 Water Drop

39 Impurities in Runoff Atmosphere Dissolved substances Silt, etc. Radon

40 Organic byproducts in water

41 Pollution Sources

42 Contamination of Water Micro-organisms Decay products Plant nutrients Petroleum compounds Acid Industry Mining

43 Raw Sewage discharge

44 Plant nutrient pollution

45 Agricultural Runoff

46 Oil pollution

47 Mine leachate

48 Water Pollution

49 Water Pollution Prevention

50 Drinking water standards

51 Quantity of hotness Celsius Temperature 0 o freezing point of pure water at standard pressure 100 o boiling point at standard pressure Fahrenheit 0 o was lowest attained 32 was his age when he performed experiments 212 is boiling point in those increments

52 Temperature Convert with equations Order of operations Parentheses first Then multiply or divide Add or subtract last Or use adjacent scales such as in the appendix of Earth Science textbook (p. 683) C = 5 9 (F -32) 9 F = C

53 Temperature Kelvin same size as degree Celsius Absolute Zero is 0 K (notice no degree symbol on K) 0 o C = 273 K Equation for Prelab exercise 2 has error K 273 = C o (change + to - )

54 Heat Calorie Amount of heat required to raise the temperature of 1 ml pure water 1 o C Food Calories are kilocalories Joule ~ ¼ of calorie 1 cal. = J

55 Specific Heat Capacity Quantity of heat needed to change the temperature of given amount of a substance 1 o C Water very high specific heat capacity Maritime areas more mild temperature than continental areas

56 Heat Expansion Random motion causes substance to be bigger Liquids usually have greater heat expansion than solids Thermostats use different expansion of different type of metals

57 Water Expansion Unusual response to cooling Contracts until reaching 4 o C Expands slightly upon further cooling to 0 o C Expands 9% upon freezing

58 Bent Polar Water Molecule

59 Water Expansion Molecule shape fit together closer in liquid Open structured crystal due to hydrogen bonding of polar molecules upon freezing

60 Water Expansion

61 Heat of Water Supplementary Textbook Materials Chapter 19 Pages

62 Electron Structure Diagrams Two ways to correctly do these With elemental symbol in center With number of protons in center Not with circles around symbol and electrons distributed around circle

63 Dot Diagrams Only show VALENCE Electrons Don t show shells

64 Phases of Matter Solid Liquid Gaseous or vapor Plasma

65 Gas, Liquid, and Solid Gas Liquid Solid Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 441

66 Evaporation Kinetic energy of molecules Taken from liquid cools it Gaseous phase or vapor phase

67 Gas Steam H 2 O(g) Steam

68 Water vapor

69 Evaporation or Not

70 Condensation Opposite of evaporation Kinetic energy of molecules Heats environment

71 Liquid Water H 2 O(l) Water

72 Condensation on Glass

73 Atmosphere Evaporation Energy goes into air Cools remaining water Condensation Energy goes from air to surface Warms local environment

74 Atmosphere Warm air has greater capacity for holding water in the vapor phase Saturation = at capacity Relative Humidity percent of water contained compared to saturated amount at that temperature

75 Water Vapor Capacity

76 Condensation

77 Condensation diagram

78 Sea Fog

79 Boiling

80 Boiling

81 Microscopic boiling

82 Pressure Cooker

83 Pressure canner

84 Boiling Temp vs.pressure

85 Boiling at less than 100 o C Reduce Pressure

86 Energy of Water Phase Change Calorie: energy to change 1 gram of water 1 K or 1 o C Also need energy to change to different state of matter Energy of vaporization/condensation 540 calories per gram of water Energy of melting/freezing 80 calories per gram

87 Heating Curve for Water 100 vaporization D E gas Temperature ( o C) 0 A solid melting B freezing C liquid condensation Heat added LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World, 1996, page 487

88 Solid Ice H 2 O(s) Ice

89 Molecular Structure of Ice Hydrogen bonding Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 455

90 Solid, Liquid, Gas (a) Particles in solid (b) Particles in liquid (c) Particles in gas