4 The Composition of Our Air in Troposphere It’s a mixture – a physical combination of two or more substances present in variable amounts.1.2
5 Air Composition Nitrogen; N2; 78 %; Oxygen; O2; 21 % Argon; Ar; 0.9 %; Other Gases; 0.1 %O2ArN2
6 Composition of the other gasses % volumeArgon (Ar)0.934%CO2350 mmvNe18.18 ppmvHe5.24 ppmvCH4KrH21.7 ppmv1.14 ppmv0.55 ppmv
7 One Breath has 2.0 X 1022 molecules 20 000 000 000 000 000 000 000 How many N2 moleculesAre in a breath of air?
8 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?0.12 O3 molecules2 x 1022 molecules and atoms in a breath of air x1 x 106 molecules and atoms in air= 2 x 1015 O3 molecules in a breathHow many oxygen atoms are in each breath?3 O atoms___2 x 1015 O3 molecules x= 6 x 1015 O atoms1 O3 molecules1.12
9 When people breathe What’s in a Breath? Typical Composition of Inhaled and Exhaled AirSubstanceInhaled air (%)Exhaled air (%)Nitrogen78.075.0Oxygen21.016.0Argon0.9Carbon dioxide0.044.0Water0.0
10 Concentration Terms Parts per hundred (percent) Parts per million (ppm)Parts per billion (ppb)Atmosphere is 21% oxygen = 21 oxygen molecules per 100 molecules of airMidday ozone levels reach about 0.4 ppm =0.4 ozone molecules x 106 molecules of airSulfur dioxide in the air should not exceed 30 ppb =30 sulfur dioxide molecules x 109 molecules of air1.2
11 21% means 21 parts per hundred means 210 parts per thousand means 2,100 parts per ten thousandmeans 21,000 parts per hundred thousandmeans 210,000 parts per millionThe difference between pph and ppm is a factor of 10,000Try Chapter 1 Figures Alive! for practice1.2
12 All Matter Classifying Matter Pure Substances Mixtures Elements NOYESCan it be separated by a physical process?Pure SubstancesMixturesCan it be broken down into simpler ones by chemical means?NOYESElementsCompounds1.6
13 Three States of MatterMatter - anything that occupies space and has mass.1.5
14 Classifying MatterClassify each of these as an element, a compound, or a mixture:carbon dioxidenickelcocainewatercompoundelementfluorinetable saltsoapsea waterelementcompoundcompoundcompoundmixturemixture1.6
16 A space filling model for a water molecule, H2O Oxygen atomA molecule is a combination of a fixed number of atoms held together in a certain spatial arrangement.The chemical formula symbolically represents the type and number of each element present.Two hydrogen atoms1.7
17 Many nonmetals occur as diatomic (made up of two atoms) moleculesH2N2O2Cl21.7
18 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 bromideBeO beryllium oxideZnS zinc sulfide1.8
19 Naming Binary Compounds 2. Prefixes are used to designate the number of each type of element:number of atoms prefix1 mono2 di3 tri4 tetra5 penta6 hexa7 hepta8 octa9 nona10 deca1.8
20 Chemical Equations Reactant(s) -> Product(s) Carbon + Oxygen -> Carbon DioxideC (s) + O2 (g) -> CO2 (g)Reactant bonds are broken; Product bonds are madeSame number and type of atoms on both sides of equation
21 C + O2 CO 2 C + O2 2 CO (balanced) Chemical reactions are characterized by the rearrangement of atoms when reactants are transformed into productsThis is an example of a combustion reactionC O2 COreactants productBut 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 atoms2 oxygen atoms two oxygen atoms1.9
24 balance anything that exists as a free element last Balancing equations:if an element is present in just one compound on each side, balance it firstbalance anything that exists as a free element lastbalance polyatomic ions as a unitcheck when done – same number of atoms, and same total charge on both sidesC3H8 + O CO2 + H2OC3H O CO H2O3 C atoms8 H atoms10 O atoms3 C atoms8 H atoms10 O atoms1.9
25 Direct Source of Sulfur Trioxide Coal O2 SO2(1-3% sulfur)2 SO O SO3Good News: Since 1985 we have seen a 25% reduction in SO emissions in the U.S.1.11
26 High temperatures from auto engine or coal-fired power plant Direct Source of Nitrogen OxidesHigh temperatures from auto engine or coal-fired power plantN O2 + high temp NO(nitrogen oxide)NO is very reactive:2 NO O NO2Simplified version of chemistry that occurs1.11
27 Properties of the troposphere Atmospheric pressure changes with altitude temperature changesIn Troposphere :Altitude increases P and T decreaseIn Thermosphere :Altitude increases P decrease, T increases
28 Quality of The Air Air Quality Index (AQI) : USA Air Pollution Index (API) : Hong Kong, China, MalaysiaIndeks Standar Pencamaran Udara (ISPU) :(Air Pollution Standard Index /APSI)Indonesia
29 Air Quality standards How are standards established? Through risk assessment--consider the toxicity of the compound and the exposure.Toxicity: How dangerous a compound is.Exposure: Refers to the length of contact with the pollutant and the concentration of the pollutant
30 EPA’s Air Quality Index Air Quality Index (AQI) ValuesLevels of Health ConcernColorsWhen the AQI is in this range:...air quality conditions are:...as symbolized by this color:050GoodGreen51–100ModerateYellow101–150Unhealthy for sensitive groupsOrange151–200UnhealthyRed201–300Very unhealthyPurple301–500HazardousMaroon1.3
31 Indonesian Air Quality Index (indeks standar pencemaran udara =ISPU) Pollutant parameters :Carbon monoksida (CO)Nitrogen (NO2)Ozone (O3)Sulfur dioxide (SO2)Particulate Matter (PM10)
32 Hubungan ISPU dan kondisi lingkungan KategoriRentangKarbon monoksida (CO)Nitrogen (NO2)Ozon (O3)Sulfur dioksida (SO2)PartikulatBaik0-50Tidak ada efekSedikit berbauLuka pada Beberapa spesies tumbuhan akibat kombinasi dengan SO2 (Selama 4 Jam)Luka pada Beberapa spesies tumbuhan akibat kombinasi dengan O3 (Selama 4 Jam)SedangPerubahan kimia darah tapi tidak terdeteksiBerbauLuka pada Beberapa spesies tumbuhanTerjadi penurunan pada jarak pandangTidak SehatPeningkatan pada kardiovaskular pada perokok yang sakit jantungBau dan kehilangan warna. Peningkatan reaktivitas pembuluh tenggorokan pada penderita asmaPenurunan kemampuan pada atlit yang berlatih kerasBau, Meningkatnya kerusakan tanamanJarak pandang turun dan terjadi pengotoran debu di mana-manaSangat Tidak SehatMeningkatnya kardiovaskular pada orang bukan perokok yang berpenyakit Jantung, dan akan tampak beberapa kelemahan yang terlihat secara nyataMeningkatnya sensitivitas pasien yang berpenyakit asma dan bronchitisOlah raga ringan mengakibatkan pengaruh parnafasan pada pasien yang berpenyaklt paru-paru kronisMeningkatnya sensitivitas pada pasien berpenyakit asma dan bronchitisBerbahaya300 - lebihTingkat yang berbahaya bagi semua populasi yang terpapar
33 API- Malaysia 0-50 Good 51-100 Moderate 101-200 Unhealthy Very unhealthy301- Hazardous
35 Air PollutionAir pollutants are airborne particles and gasses that occur in concentrations that endanger the health and well-being of organisms or disrupt the orderly functioning of the environment.Pollutants can be grouped into two categories:(1) primary pollutants, which are emitted directly from identifiable sources, and(2) secondary pollutants, which are produced in the atmosphere when certain chemical reactions take place among primary pollutants.
36 Primary Pollutants The major primary pollutants include: particulate matter (PM),sulfur dioxide,nitrogen oxides,volatile organic compounds (VOCs),carbon monoxide, andlead.
39 Secondary PollutantsAtmospheric sulfuric acid is one example of a secondary pollutant.Air pollution in urban and industrial areas is often called smog.Photochemical smog, a noxious mixture of gases and particles, is produced when strong sunlight triggers photochemical reactions in the atmosphere.The major component of photochemical smog is ozone.Although considerable progress has been made in controlling air pollution, the quality of the air we breathe remains a serious public health problem.
40 Major Sources of Air Pollutants Combustion of coal in coal burning power plantsCoal is mostly Carbon; The main impurity in coal is sulfur, S.Combustion of fuel in car, trucks, and other vehicles.
41 Sulfur Oxides, SOx SO2, SO3When coal is burned, so is the Sulfur impurityS + O2SO2
42 The SO2 then burns to produce SO3. 2 SO O22 SO3
43 SO3 gas then dissolve in water to make a component of acid rain, H2SO4 (aq). SO3 (g) + H2O (l)H2SO4 (aq)In general; nonmetal oxides dissolve in water to make it acidic
44 Problems with SOx SOx are respiratory irritants SOx dissolve in water to make a component of acid rain.
47 Carbon Monoxide, CO 50 ppm Impair human reflexes; affect vision Headache, fatigue, dizziness, shortness of breath750 ppmUnconsciousness, death
48 Reducing CO Emissions Post Combustion Change/Replace Combustion ProcessPre-Combustion
49 Catalytic ConverterPrinciples of Environmental Chemistry; by James E Girard;Jones and Bartlett Publisher, Inc; 2005, pg121
50 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 exhaust1.11
51 Volatile Organic Compounds (VOC) Formed with CO during Incomplete CombustionWays to Reduce are the Same as COPrecursor to Nitrogen Dioxide, NO2, and Ozone, O3, Formation
52 Lead Sources Effects Toxic Can cause neurological problems in kids Tetraethyl lead (TEL) added to gasoline to make it burn more smoothly, “anti-knocking” agentEffectsToxicCan cause neurological problems in kidsLeaded Fuel banned in United States; 1997
54 Health Effects of Nitrogen Oxides Respiratory Irritant-Aggravate conditions like chronic bronchitis and asthmaPrecursor to Ozone, O3, formationNitrogen Oxides Dissolve in Water to Make it AcidicNO(g) + NO2 (g) + H2O (l)HNO3 (aq) + HNO2 (aq)* Unbalanced equation
55 Low TemperatureMaximize VOC and COHigh TemperatureMaximize NOx
56 Role of VOC in formation of NO2 Normally, the following reaction is very slowNO (g) + O2 (g) -> 2 NO2 (g)VOC’s and the hydroxyl radical (*OH) form an intermediatewhich reacts with oxygen to make the above reaction happenat a faster rate.
57 Photochemical Air Pollutants Secondary Air Pollutants Produced by SunlightOzone, O3, is a photochemical air pollutant and is formed by….NOx + Sunlight -> Ozone (Photochemical Pollutants)VOC + Sunlight -> Ozone (Photochemical Pollutants)
58 Primary Air PollutantSecondary Air PollutantNONO2HNO2, HNO3O3 (photochemical)
63 Raven/Berg; Environment 4/e, John Wiley and Sons Inc, p 444, Figure 19
64 Problems with Ozone, O3 Lung Irritant,can cause coughing Makes Eyes BurnReacts with Other Air Pollutants (like VOC) to Make Components of Photochemical SmogPowerful Oxidizing AgentCauses rubber to crackDamages Plants
65 Ozone Can Contribute to Chemical Weathering in Automobile Tires Chemistry; The Science in Context; Thomas R Gilbert, Rein V Kirss, and GeoffreyDavies, Norton Publishers, 2004.
67 Effect of Season On Ozone Concentrations in Troposphere Effect of SeasonOn OzoneConcentrations inTroposphere
68 Particulate Matter (PM) Particles of Dispersed Matter (solid or liquid) that are larger than individual moleculesAerosolsDustFumesMist/FogSmoke, Soot, AshSmogPollenPM10; avg diameter less than 10 micronsPM2.5; avg diameter less than 2.5 microns
69 Effect of Particulate Matter Impair breathing since small enough to get to lungsReduce visibility since large enough to scatter light.Toxic chemicals can adsorb to surface (Cd, Ni, pesticides)
70 Reducing Particulate Pollution From Man-Made Sources Cyclone PrecipitatorElectrostatic PrecipitatorBaghouses
82 Air Pollution Occurrences The most obvious factor influencing air pollution is the quantity of contaminants emitted into the atmosphere.However, when air pollution episodes take place, they are not generally the result of a drastic increase in the output of pollutants; instead, they occur because of changes in certain atmospheric conditions.Two of the most important atmospheric conditions affecting the dispersion of pollutants are:(1) the strength of the wind and(2) the stability of the air.
83 Air MixingThe direct effect of wind speed is to influence the concentration of pollutants.Atmospheric stability determines the extent to which vertical motions will mix the pollution with cleaner air above the surface layers.The vertical distance between Earth's surface and the height to which convectional movements extend is called the mixing depth.Generally, the greater the mixing depth, the better the air quality.
84 InversionsTemperature inversions represent a situation in which the atmosphere is very stable and the mixing depth is significantly restricted.When an inversion exists and winds are light, diffusion is inhibited and high pollution concentrations are to be expected in areas where pollution sources exist.Surface temperature inversions form because the ground is a more effective radiator than the air above. Inversions aloft are associated with sinking air that characterizes centers of high air pressure (anticyclones).
86 This is an example of a generalized temperature profile for a surface inversion. Temperature-profile changes in bottom diagram after the sun has heated the surface.
87 HOW CAN WE STOP AIR POLLUTION? Stop producing it in the first place.Government can pass laws that forbid or limit the use off chemicals that cause pollution.Build cars that burn less gasoline.Recycling helps cut down on pollution.