The Air We Breathe Chapter One What is in the air that we breathe?

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The Air We Breathe Chapter One What is in the air that we breathe?
Can air be dangerous to our health? How can understanding chemistry help us decide? Catatan: Diambil dari berbagai sumber

Where are we leaving ?

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

Air Composition Nitrogen; N2; 78 %; Oxygen; O2; 21 %
Argon; Ar; 0.9 %; Other Gases; 0.1 % O2 Ar N2

Composition of the other gasses
% volume Argon (Ar) 0.934% CO2 350 mmv Ne 18.18 ppmv He 5.24 ppmv CH4 Kr H2 1.7 ppmv 1.14 ppmv 0.55 ppmv

One Breath has 2.0 X 1022 molecules 20 000 000 000 000 000 000 000
How many N2 molecules Are in a breath of air?

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 molecules 2 x 1022 molecules and atoms in a breath of air x 1 x 106 molecules and atoms in air = 2 x 1015 O3 molecules in a breath How many oxygen atoms are in each breath? 3 O atoms___ 2 x 1015 O3 molecules x = 6 x 1015 O atoms 1 O3 molecules 1.12

When people breathe What’s in a Breath?
Typical Composition of Inhaled and Exhaled Air Substance Inhaled air (%) Exhaled air (%) Nitrogen 78.0 75.0 Oxygen 21.0 16.0 Argon 0.9 Carbon dioxide 0.04 4.0 Water 0.0

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 air Midday ozone levels reach about 0.4 ppm = 0.4 ozone molecules x 106 molecules of air Sulfur dioxide in the air should not exceed 30 ppb = 30 sulfur dioxide molecules 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 The difference between pph and ppm is a factor of 10,000 Try Chapter 1 Figures Alive! for practice 1.2

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

Three States of Matter Matter - anything that occupies space and has mass. 1.5

Classifying Matter Classify each of these as an element, a compound, or a mixture: carbon dioxide nickel cocaine water compound element fluorine table salt soap sea water element compound compound compound mixture mixture 1.6

The Periodic Table Group Period

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. The chemical formula symbolically represents the type and number of each element present. Two hydrogen atoms 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 Binary Compounds
2. Prefixes are used to designate the number of each type of element: number of atoms prefix 1 mono 2 di 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octa 9 nona 10 deca 1.8

Chemical Equations Reactant(s) -> Product(s)
Carbon + Oxygen -> Carbon Dioxide C (s) + O2 (g) -> CO2 (g) Reactant bonds are broken; Product bonds are made Same number and type of atoms on both sides of equation

C + O2 CO 2 C + O2 2 CO (balanced)
Chemical reactions are characterized by the rearrangement of atoms when reactants are transformed into products This is an example of a combustion reaction C O2 CO reactants product 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

2 C O CO + 1.9

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 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 + O CO2 + H2O C3H O CO H2O 3 C atoms 8 H atoms 10 O atoms 3 C atoms 8 H atoms 10 O atoms 1.9

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

High temperatures from auto engine or coal-fired power plant
Direct Source of Nitrogen Oxides High temperatures from auto engine or coal-fired power plant N O2 + high temp NO (nitrogen oxide) NO is very reactive: 2 NO O NO2 Simplified version of chemistry that occurs 1.11

Properties of the troposphere
Atmospheric pressure changes with altitude temperature changes In Troposphere : Altitude increases  P and T decrease In Thermosphere : Altitude increases  P decrease, T increases

Quality of The Air Air Quality Index (AQI) : USA
Air Pollution Index (API) : Hong Kong, China, Malaysia Indeks Standar Pencamaran Udara (ISPU) : (Air Pollution Standard Index /APSI) Indonesia

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

EPA’s Air Quality Index
Air Quality Index (AQI) Values Levels of Health Concern Colors When the AQI is in this range: ...air quality conditions are: ...as symbolized by this color: 050 Good Green 51–100 Moderate Yellow 101–150 Unhealthy for sensitive groups Orange 151–200 Unhealthy Red 201–300 Very unhealthy Purple 301–500 Hazardous Maroon 1.3

Indonesian Air Quality Index (indeks standar pencemaran udara =ISPU)
Pollutant parameters : Carbon monoksida (CO) Nitrogen (NO2) Ozone (O3) Sulfur dioxide (SO2) Particulate Matter (PM10)

Hubungan ISPU dan kondisi lingkungan

API- Malaysia 0-50 Good 51-100 Moderate 101-200 Unhealthy
Very unhealthy 301- Hazardous

Air Pollution Air 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.

Primary Pollutants The major primary pollutants include:
particulate matter (PM), sulfur dioxide, nitrogen oxides, volatile organic compounds (VOCs), carbon monoxide, and lead.

Secondary Pollutants Atmospheric 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.

Major Sources of Air Pollutants
Combustion of coal in coal burning power plants Coal is mostly Carbon; The main impurity in coal is sulfur, S. Combustion of fuel in car, trucks, and other vehicles.

Sulfur Oxides, SOx SO2, SO3 When coal is burned, so is the Sulfur impurity S + O2 SO2

The SO2 then burns to produce SO3.
2 SO O2 2 SO3

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

Problems with SOx SOx are respiratory irritants
SOx dissolve in water to make a component of acid rain.

Scrubber

Carbon Monoxide, CO COMPLETE COMBUSTION INCOMPLETE COMBUSTION
CxHy (l) + O2 (g) -> CO2 (g) + H2O (g) INCOMPLETE COMBUSTION CxHy (l) + O2 (g) -> CO (g) + H2O (g) +VOC (g)

Carbon Monoxide, CO 50 ppm Impair human reflexes; affect vision
Headache, fatigue, dizziness, shortness of breath 750 ppm Unconsciousness, death

Reducing CO Emissions Post Combustion
Change/Replace Combustion Process Pre-Combustion

Catalytic Converter Principles of Environmental Chemistry; by James E Girard;Jones and Bartlett Publisher, Inc; 2005, pg121

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 1.11

Volatile Organic Compounds (VOC)
Formed with CO during Incomplete Combustion Ways to Reduce are the Same as CO Precursor to Nitrogen Dioxide, NO2, and Ozone, O3, Formation

Lead Sources Effects Toxic Can cause neurological problems in kids
Tetraethyl lead (TEL) added to gasoline to make it burn more smoothly, “anti-knocking” agent Effects Toxic Can cause neurological problems in kids Leaded Fuel banned in United States; 1997

Nitrogen Oxides, NOx NO, NO2
Low Temperatures N2 (g) + O2 (g) -> No Reactions High Temperatures/ High Pressure N2 (g) + O2 (g) -> 2 NO(g) NO (g) + O2 (g) -> 2 NO2 (g)

Health Effects of Nitrogen Oxides
Respiratory Irritant-Aggravate conditions like chronic bronchitis and asthma Precursor to Ozone, O3, formation Nitrogen Oxides Dissolve in Water to Make it Acidic NO(g) + NO2 (g) + H2O (l) HNO3 (aq) + HNO2 (aq) * Unbalanced equation

Low Temperature Maximize VOC and CO High Temperature Maximize NOx

Role of VOC in formation of NO2
Normally, the following reaction is very slow NO (g) + O2 (g) -> 2 NO2 (g) VOC’s and the hydroxyl radical (*OH) form an intermediate which reacts with oxygen to make the above reaction happen at a faster rate.

Photochemical Air Pollutants
Secondary Air Pollutants Produced by Sunlight Ozone, O3, is a photochemical air pollutant and is formed by…. NOx + Sunlight -> Ozone (Photochemical Pollutants) VOC + Sunlight -> Ozone (Photochemical Pollutants)

Primary Air Pollutant Secondary Air Pollutant NO NO2 HNO2, HNO3 O3 (photochemical)

Photochemical Smog

Formation of Photochemical Air Pollutant; Ozone, O3
NO2 + Sunlight  NO + O O + O2  O3

Raven/Berg; Environment 4/e, John Wiley and Sons Inc, p 444, Figure 19

Problems with Ozone, O3 Lung Irritant,can cause coughing
Makes Eyes Burn Reacts with Other Air Pollutants (like VOC) to Make Components of Photochemical Smog Powerful Oxidizing Agent Causes rubber to crack Damages Plants

Ozone Can Contribute to Chemical Weathering in Automobile Tires
Chemistry; The Science in Context; Thomas R Gilbert, Rein V Kirss, and Geoffrey Davies, Norton Publishers, 2004.

Ozone Damaged Plant

Effect of Season On Ozone Concentrations in Troposphere
Effect of Season On Ozone Concentrations in Troposphere

Particulate Matter (PM)
Particles of Dispersed Matter (solid or liquid) that are larger than individual molecules Aerosols Dust Fumes Mist/Fog Smoke, Soot, Ash Smog Pollen PM10; avg diameter less than 10 microns PM2.5; avg diameter less than 2.5 microns

Effect of Particulate Matter
Impair breathing since small enough to get to lungs Reduce visibility since large enough to scatter light. Toxic chemicals can adsorb to surface (Cd, Ni, pesticides)

Reducing Particulate Pollution From Man-Made Sources
Cyclone Precipitator Electrostatic Precipitator Baghouses

Cyclone Precipitator

Electrostatic Precipitator

Baghouse

Sources of Air Pollutants

Sources of Air Pollutants (continued)

Indoor Air Pollution Combustion Indoor VOC Radon Gas NOx, CO, VOC
Cigarettes, burning candles Indoor VOC Paint, fingernail polish, glues… Radon Gas

Indoor Air Pollutants? 1.14

Indoor Air Pollution

Lead-214 27 minutes Polonium-218 187 seconds Radon-222 3.8 days Air Radium-226 1600 years Soil 5 Transformations Rock Uranium – 238 4.5 billion years

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.

Air Mixing The 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.

Inversions Temperature 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).

Inversion

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.

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.

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