1 / 41

Chapter One

Chapter One. The Air We Breathe. What is in the air that we breathe?. Can air be dangerous to our health?. How can understanding chemistry help us decide?. Winter Haze in Paris: Looking down the Champs Elysees from the top of the Arc de Triomphe. Outdoor Air Pollution. The Bad Gases.

vlad
Download Presentation

Chapter One

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter One The Air We Breathe What is in the air that we breathe? Can air be dangerous to our health? How can understanding chemistry help us decide?

  2. Winter Haze in Paris: Looking down the Champs Elysees from the top of the Arc de Triomphe Outdoor Air Pollution

  3. The Bad Gases • Carbon monoxide • Ozone • Sulfur oxides and nitrogen oxides • Particulate matter, PM Air Pollution: Gases or particles in the air in high enough concentrations to harm living systems or organisms.. 1.2

  4. Indoor Air Pollutants? – Cigarette smoke, oven cleaner fumes, asbestos particles … even radon gas. Do you think of harmful pollutants when you light your incense candle or want to begin painting a room in the house? Why do you think these are considered indoor air pollutants? 1.13

  5. The Good Ones - The Composition of Our Air It’s a mixture – a physical combination of two or more substances present in variable amounts. 1.1

  6. Typical Composition of Inhaled and Exhaled Air What’s in a Breath? 1.1

  7. Air Pollutants: Risk Assessment RiskAssessment – evaluating data and making predictions in an organized manner about the probabilities of an occurrence. Toxicity– intrinsic health hazard of a substance. Exposure– the amount of the substance encountered. 1.3

  8. Average concentrations of air pollutants at selected locations in the U.S., in comparison with national ambient air quality standards. 1.4

  9. How do we reduce outdoor air pollution? 1.4

  10. EPA’s Air Quality Index http://www.airnow.gov / 1.4

  11. Concentration Terms Parts per hundred (percent) Parts per million (ppm) Parts per billion (ppb) Atmosphere is 21% oxygen = 21 oxygen molecules per 100 molecules and atoms in air Midday ozone levels reach about 0.4 ppm = 0.4 ozone molecules 1 x 106 molecules and atoms in air Sulfur dioxide in the air should not exceed 30 ppb = 30 sulfur dioxide molecules1 x109 molecules and atoms in air 1.2

  12. 21% means 21 parts per hundred means 210 parts per thousand means 2,100 parts per ten thousand means 21,000 parts per hundred thousand means 210,000 parts per million The difference between pph and ppm is a factor of 10,000 Try the Water Vapor in Air ChemActivity! 1.2

  13. Measurements

  14. Nature of Measurement Measurement - quantitative observation consisting of 2 parts Part 1 - number Part 2 - scale (unit) Examples: 25.6 mmHg (Pressure) 6.63 ´102 L (Volume) 234 K (Temperature)

  15. Force Area Barometer Pressure = Units of Pressure 1 pascal (Pa) = 1 N/m2 1 atm = 760 mmHg = 760 torr 1 atm = 101,325 Pa 5.2

  16. V decreases As P (h) increases 5.3

  17. International System(le Système International) Based on metric system and units derived from metric system.

  18. The Fundamental SI Units

  19. Uncertainty in Measurement A digit that must be estimated is called uncertain. A measurementalways has some degree of uncertainty in the last digit reported.

  20. Precision and Accuracy Accuracy refers to the agreement of a particular value with the truevalue. Precisionrefers to the degree of agreement among several measurements of the same quantity.

  21. Significant Figures - Overview 1. Nonzero integers 2. Zeros leading zeros captive zeros trailing zeros 3. Exact numbers

  22. Significant Figures - Details Nonzero integersalways count as significant figures. 3456

  23. Significant Figures - Details Zeros Leading zeros do not count as significant figures. 0.0486

  24. Significant Figures - Details Zeros Captive zeros always count as significant figures. 16.07

  25. Significant Figures - Details Zeros Trailing zeros are significant only if the number contains a decimal point. 9.300

  26. Significant Figures - Details Zeros Trailing zeros are significant only if the number contains a decimal point. 9300

  27. Significant Figures - Details Zeros 9300 could be 2, could be 3, could be 4??? It is ambiguous. Therefore, Change it to Scientific Notation

  28. Significant Figures - Details Zeros 9300 2 sig figs 9.3 X 103 3 sig figs 9.30 X 103 4 sig figs 9.300 X 103

  29. OK – We Can Measure Stuff • What is the identity of the stuff we are measuring anyway? • Mixtures • Pure Substances • Compounds • Elements

  30. Classifying Matter All Matter NO YES Can it be separated by a physical process? PureSubstances Mixtures Can it be broken down into simpler ones by chemical means? NO YES Elements Compounds 1.6

  31. The Periodic Table Group Period 1.6

  32. A space-filling model for a water molecule, H2O Oxygen atom Amoleculeis a fixed number of atoms held together by chemical bonds in a certain spatial arrangement. Thechemical formulasymbolically represents the type and number of each element present. Two hydrogen atoms 1.7

  33. Many nonmetals occur asdiatomic (made up of two atoms) molecules. Cl2 O2 H2 N2 1.7

  34. Naming Binary Compounds 1. Prefixes are used to designate the number of each type of element: number of atomsprefix 1 mono 2 di 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octa 9 nona 10 deca 1.8

  35. Naming Binary Compounds of Nonmetals 2. Prefixes are used to designate the number of each type of element: N2O = dinitrogen monoxide (laughing gas) P2O5=diphosphorus pentoxide Notice the dropped “a” from “penta” – when both the prefix and suffix (in this case “oxide”) end and start, respectively, in a vowel, the vowel of the prefix is typically dropped; pentoxide rather than pentaoxide. 1.8

  36. Chemical reactionsare characterized by the rearrangement of atoms whenreactants are transformed intoproducts. This is an example of acombustion reaction C + O2 CO reactantsproduct But the number of atoms on each side of the arrow must be equal (Law of Conservation of Mass). 2 C + O2 2 CO (balanced) 2 carbon atoms two carbon atoms 2 oxygen atoms two oxygen atoms 1.9

  37. 2 C + O2 2 CO Another look, pictorially – using space-filling models 1.9

  38. Balancing equations: • if an element is present in just one compound on each side, balance it first • balance anything that exists as a free element last • balance polyatomic ions as a unit • check when done – same number of atoms, and same total charge (if any) on both sides C3H8 + O2 CO2 + H2O C3H8 + 5 O2 3 CO2 + 4 H2O 3 C atoms 8 H atoms 10 O atoms 3 C atoms 8 H atoms 10 O atoms 1.9

  39. Direct Source of Sulfur Trioxide Coal + O2 SO2 (1–3% sulfur) 2 SO2 + O2 2 SO3 Good News: Since 1985 we have seen a 25% reduction in SO2 emissions in the U.S. 1.11

  40. Direct Source of Nitrogen Oxides High temperaturesfrom auto engine or coal-fired power plant N2 + O2 +high temp2 NO (nitrogen oxide) Simplified version of chemistry that occurs NO is very reactive: 2 NO + O2 2 NO2 1.11

  41. Catalytic converters are used to catalyze the conversion of CO to CO2 The converters also reduce the amount of Volatile Organic Compounds (VOCs) from tailpipe exhaust. One reason for removing tetraethyl lead from gasoline is that the lead gunked up or poisoned the catalysts in the converters. The other reason was to reduce the amount of lead in the air. 1.11

More Related