Chapter 1 Powerpoint

Chapter 1 Powerpoint - Chapter 1 Overview Components of Air...

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Unformatted text preview: Chapter 1 Overview Components of Air Pollutants AQI Values Exposure and Toxicity Regions of Atmosphere Concentration Units Classification of Matter Periodic Table Atoms and Molecules Naming Compounds and Elements Chemical Formulas Balancing Chemical Equations Ozone Scientific Notation The Composition of Our Air It's a mixture a physical combination of two or more substances present in variable amounts 1.2 Typical Composition of Inhaled and Exhaled Air Substance What's in a Breath? Nitrogen Oxygen Argon Carbon dioxide Water Inhaled air (%) 78.0 21.0 0.9 0.04 0.0 Exhaled air (%) 75.0 16.0 0.9 4.0 4.0 1.2 Concentration Terms Parts per hundred (percent) Atmosphere is 21% oxygen = 21 oxygen molecules per 100 molecules of air Parts per million (ppm) Midday ozone levels reach about 0.4 ppm = 0.4 ozone molecules 1 x 106 molecules of air Parts per billion (ppb) Sulfur dioxide in the air should not exceed 30 ppb = 30 sulfur dioxide molecules 1 x 109 molecules of air 1.2 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 1.2 Suppose a particular pollutant gas is present at a concentration of 1550ppm in the air. What is this concentration expressed as a percentage? For a 1000 liter sample of air, what volume of the pollutant gas will be present? Equal volumes of gases contain equal numbers of molecules (at the same temperature and pressure). Gas Volume and Number of Molecules Thus, a sample of gas which is 78% nitrogen 21% oxygen, and 1% argon (by volume) contains 78 molecules of nitrogen, 21 molecules of oxygen, and 1 molecule of argon for every 100 molecules of the gas sample. Example Problem What is the concentration of a pollutant gas in parts per billion (ppb) if it is present in the air at a concentration of 0.0155 %? Common Pollutants Carbon Monoxide Ozone Sulfur Oxides Nitrogen Oxides Particulate Matter Carbon Monoxide (CO): Odorless Disrupts delivery of oxygen in the body Causes dizziness, headache nausea Ozone (O3): Distinctive, sharp odor Reduces lung function during exercise Causes chest pain, coughing, congestion Sulfur Oxides (SOx) And Nitrogen Oxides (NOx) Respiratory irritants Lower resistance to respiratory infection Elderly and young most affected Particulate Matter (PM) Tiny (~ 10 um or less) solid or liquid particles Includes soot, smoke, bacteria, viruses Smaller particular sizes (< 2.5 um) are most toxic, associated with heart disease Fig.01.06 EPA's Air Quality Index Air Quality Index Levels of Health (AQI) Values Concern When the AQI is in this range: 0- 50 51100 101150 151200 201300 301500 ...air quality conditions are: Good Moderate Unhealthy for sensitive groups Unhealthy Very unhealthy Hazardous Colors symbolized by this color: Green Yellow Orange Red Purple Maroon 1.3 Fig.01.07 Table 1.4 Air Quality Index values for Houston Year Good (050) Moderate (51100) Unhealthy for Sensitive Groups (101150) Unhealthy (>150) 1997 1998 1999 2000 2001 2002 2003 258 253 223 166 180 196 161 54 70 82 147 144 136 132 33 23 34 37 25 24 26 20 19 26 16 16 9 16 1.3 The Clean Air Act A federal mandate to reduce air pollution and establish air quality standards Established in 1970 The Environmental Protection Agency (EPA) established permissible levels of air pollutants based on health risks and environmental effects Tbl.01.05 Tbl.01.01 Air Pollutants: Risk Assessment Toxicity intrinsic health hazard of a substance Exposure the amount of the substance encountered 1.4 Tbl.01.05 Calculating Pollutant Exposure What is a person's daily exposure to Carbon Monoxide at a concentration of 5000 ug / m3? (assume the person breathes 10,000 Liters of air per day) Is this exposure to carbon monoxide above the National Air Quaility Standard? International System (le Systme International) Based on metric system and units derived from metric system. The Fundamental SI Units Physical Quantity Mass Length Time Temperature Electric Current Amount of Substance Luminous Intensity Name kilogram meter second Kelvin Ampere mole candela Abbreviation kg m s K A mol cd Scientific Notation Examples 325,000 written as : 3.25 X 105 0.00325 written as : 3.25 X 10-3 35,000,000 written as 3.5 X 107 .0000000025 written as 2.5 X 10-9 Scientific Notation Practice Convert the following numbers from scientific notation to standard notation: 3.570 X 105 4.68 X 10-3 Scientific Notation Practice Write the following numbers in scientific notation: 325,000,000,000 0.00005700 Fig.pr01.49 Fig.01.08 Fig.01.10 Classifying Matter All Matter NO Can it be separated by a physical process? YES Pure Substances NO Can it be broken down into simpler ones by chemical means? YES Mixtures Elements Compounds 1.6 Classifying Matter Classify each of the following as either a mixture or pure substance. If it is a pure substance, is it a compound or element? air Water (H2O) Carbon dioxide (CO2) Oxygen (O2) Sugar dissolved in water Ozone (O3) The Periodic Table Group Period Periodic Table Practice Are the following metals or nonmetals? What period and group do they belong to? Oxygen (O) Nitrogen (N) Sodium (Na) Fluorine (F) Calcium (Ca) Atoms, Molecules and Chemical Formulas Atoms: The smallest unit of an element that can exist as that element. Example: N Molecules and Chemical Formulas: Molecules are assemblies of two or more atoms bonded together. Examples: carbon dioxide, ozone, water Each molecule has a chemical formula: CO2 The chemical formula indicates which atoms are found in the molecule, and in what proportion they are found. A space filling model for a water molecule, H2O Oxygen atom A molecule is a combination of a fixed number of atoms held together in a certain spatial arrangement. Two hydrogen atoms The chemical formula symbolically represents the type and number of each element present. 1.7 Many nonmetals occur as diatomic (made up of two atoms) molecules H2 N2 O2 Cl2 1.7 Naming Binary Compounds 1. Name the more metallic element first, followed by the name of the less metallic element, modified with the suffix "ide" KBr postassium bromide BeO beryllium oxide ZnS zinc sulfide 1.8 Naming Practice Name the compound that contains each pair of elements: Bromine and magnesium Hydrogen and chlorine Sulfur and sodium Naming Binary Compounds (cont) (for compounds containing only nonmetals) 2. Prefixes are used to designate the number of each type of element: number of atoms 1 2 3 4 5 6 7 8 9 10 prefix mono di tri tetra penta hexa hepta octa nona deca 1.8 Naming Compounds Composed of Nonmetals Name the following compounds: NO2 SO2 SO3 N 2O 4 CCl4 Chemical reactions are characterized by the rearrangement of atoms when reactants are transformed into products C + O2 reactants CO product This is an example of a combustion reaction But the number of atoms on each side of the arrow must be equal (Law of Conservation of Mass) 2 C + O2 2 carbon atoms 2 oxygen atoms 2 CO (balanced) two carbon atoms two oxygen atoms 1.9 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 on both sides C3H8 + O2 C3H8 + 5 O2 3 C atoms 8 H atoms 10 O atoms CO2 + H2O 3 CO2 + 4 H2O 3 C atoms 8 H atoms 10 O atoms 1.9 2C + O2 2 CO + Combustion: Chemical reaction of a substance with oxygen (O2) Many air pollutants results from combustion reactions (e.g., CO, CO2, SO2, SO3, NO, NO2, etc) 1.9 Direct Source of Carbon Monoxide and Carbon Dioxide Most carbon monoxide and carbon dioxide is produced by the combustion of hydrocarbons. Hydrocarbon: A compound containing only carbon and oxygen. Common hydrocarbons: gasoline, methane (CH4), propane (C3H8), coal Examples of Hydrocarbon Combustion: Octane Production of Carbon Dioxide: 2C8H18 + 25 O2 16 CO2 + 18 H2O Production of Carbon Monoxide: 2C8H18 + 17 O2 16 CO + 18 H2O Fig.pr01.50 Catalytic converters are used to catalyze the conversion of CO to CO2 (also, catalytic converters catalyze the combustion of hydrocarbons to form carbon dioxide and water) The converters also reduce the amount of Volatile Organic Compounds (VOCs) from tailpipe exhaust Direct Source of Sulfur Trioxide Coal (1-3% sulfur) + O2 SO2 2 SO2 + O2 2 SO3 Good News: Since 1985 we have seen a 25% reduction in SO2 emissions in the U.S. Direct Source of Nitrogen Oxides High temperatures from auto engine or 2 NO coal-fired power plant (nitrogen oxide) N2 + O2 + high temp NO is very reactive: 2 NO + O2 2 NO2 Simplified version of chemistry that occurs Formation of Tropospheric Ozone NO2 sunlight NO + O O3 O + O2 O3 is not directly emitted, it is a secondary pollutantproduced from other pollutants Ozone (O3) If one breath of air contains 2 x 1022 molecules and atoms, and the acceptable ozone level is 0.12 ppm, how many molecules of O3 are in each breath? 2 x 1022 molecules and atoms in a breath of air x 0.12 O3 molecules 1 x 106 molecules and atoms in air = 2 x 1015 O3 molecules in a breath How many oxygen atoms are in each breath (from the ozone)? 2 x 1015 O3 molecules x 3 O atoms___ 1 O3 molecules = 6 x 1015 O atoms Indoor Air Pollutants? 1.14 Tbl.01.10 Template Text ...
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This note was uploaded on 04/07/2008 for the course CHEM 1?? taught by Professor Mcgrath during the Fall '08 term at Mary Washington.

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