IB Chemistry III: Air PollutionThe book: pp. 131, 133, 134, 139-141

Guide outline:1. Definitions and lists2. Causes and effects3. Methods of removal

I. Definitions and lists

Primary Pollutants: Damaging substances directly released into air, that are not normally present or are present in unnatural proportions

1. CO2. NOx

3. SO2 and SO3

4. Particulates: eg. Soot, ash, burned fossil fuels5. VOC’s: Volatile organic compounds

Secondary Pollutants: Damaging substances formed by reaction of primary pollutants with catalysts or other present substances.

1. Hydroxyl radicals (OH∙)2. Nitric acid (HNO3)3. Radicals in general4. PAN (peroxyacylnitrate…)

Greenhouse Effect: The warming of the earth due to radiation-retentive atmospheric gases (radiation is either trapped and accumulated in the air or reflected by earth’s surface and absorbed upon return to the stratosphere). Gases allow short-wave radiation through, later to absorb it.

Greenhouse Gases:1. O3

2. CO2

3. CH4

4. H2O5. NOx

Radioactive Waste: Radioactive material of varying intensity.

High-level: Directly radioactive material, eg. spent fuel rods

Low-level: Material exposed to radiation, eg. experimental packaging

Smog: Poisonous mixture of smoke, fog, air, and other chemicals.

Reducing smog = Result of combustion of coal and oil, producing sulfur dioxide and soot/ash. Pea soup color.

Photochemical smog = Consists of primary pollutants (NOx and VOCs) then converted into secondary pollutants by sunlight. Yellow-brown color. (* see equations section for formation)

Other definitions may be found in the following sections.

II. Causes and Effects

Primary Pollutants: Sources and effectsPollutant Man-made Natural EffectCO Incomplete

combustion of fossil fuels

Incomplete oxidation of methane

Prevents hemoglobin from carrying oxygen

NOx Internal combustion engines

Electrical storms; biological processes

Respiratory irritant; can cause acid rain

SO2 and SO3 Combustion of coal and smelting of ores

Oxidation of H2S from volcanoes; decay of org’c matter

Respiratory irritant; can also cause acid rain

Particulates Burning of fossil fuels,

Soot, ash, dust,

Respiratory irritant; can

esp. coal and diesel

asbestos, sand, smoke, pollen, bacterial/fungal spores

cause lung disease (emphysema, cancer)*They can also reverse global warming by scattering short-waved light

VOCs Unburned/partly burned gasoline; solvents

Plants (like rice—so real plants); terpenes

Carcinogenic (esp. benzene); can form PANs

Ozone and CFCsType EffectOzone (O3 gas) Greenhouse gas; retains

radiation to warm earth and reflects it to cool it

CFCs (chlorofluorocarbons) Destroys ozone; reverses greenhouse effect

III. Methods of Removal

Primary Pollutants: Methods of Removal/Reduction

Method Description Pollutant(s) it reduces

Electrostatic Precipitation

Particulates are charged and attracted to electrodes, then removed

Particulates

Fluidized Bed Combustion

Coal burned on bed of limestone, which removes

Sulfur dioxide

sulfurCoal cleaning Coal crushed and

sulfur removedSulfur dioxide

Coal scrubbing Alkaline slurry: coal gas exposed to limestone, which removes sulfur into sludge

Sulfur dioxide

Thermal exhaust Reactor

CO reacted with excess oxygen to produce CO2

CO

Lean-burn engines Ratio of NOx to CO altered; one reduced but other increased

NOx or CO

Catalytic converter NOx catalyzed (using palladium, platinum, or rhodium) with CO to produce CO2 and nitrogen

NOx and CO

Nuclear Waste: Removal ProcessesType ProcessHigh-Level Vitrification (waste is dried

and then melted, solidified in steel, cooled, and buried in geologically stable conditions)

Low-Level Discharge into sea; cooled in ‘ponds’ and passed through ion exchange to remove strontium and cesium; kept in concrete vaults

When in doubtThe universal answer for reduction of

pollutants:CUT BACK!!!

IV. Formulas

Creation of primary pollutantsPollutant Man-Made NaturalCO C8H18 + 17/2 O2 8CO +

9H2OCH4 + 3/2 O2 CO + 2H2O

NOx N2 + O2 2NO Etc.SO2 H2S + O2 H2 + SO2 S + O2 SO2

Alkaline Scrubbing:CaCO3 + SO2 Ca SO3 + CO2

CaO + SO2 Ca SO3

2CaSO3 + O2 + 4H2O 2CaSO4.2H2O

Catalytic Conversion:2CO + 2NO –platinum/rhodium/palladium –> 2CO2 + N2

Creation of Ozone w/UV catalystO2 2O∙O∙ + O2 O3

Depletion of OzoneCause Formula(s)Natural (UV) O3 O2 + O∙

O3 + O∙ 2O2

CFCs CCl2F2 CClF2 + Cl∙Cl∙ + O3 ClO∙ + O2

ClO∙ + O∙ Cl∙ + O2

Nitrogen oxides 2O3 –NO2—> 3O2

Formation of Secondary Pollutants

(pay especial attention to top and bottom rxns)

Nitrogen oxide radicalization NO2 NO + O∙Hydroxyl radicalization O∙ + H2O 2OH∙Nitric Acid formation OH∙ + NO2 HNO3

Radical Propagation OH∙ + RH R∙ + H2OPeroxide Radical formation R∙ + O2 ROO∙PAN formation Peroxide radical + nitrogen

dioxide

Waste disposal is left to you, because it is relatively straightforward and well-organized in the book.

Thank you and good luck!