Fundamentals. Chapter 2: Properties and Fundamentals. Formation of ozone and photochemical

Transcription

1 hapter Properties and Fundamentals Importance of rganic ompounds Volatile compounds contribute to the formation of ozone and photochemical oxidants ompounds can have toxic effects on plants and animals Topics overed Review of organic chemistry Formation of ozone and photochemical smog Properties of organic vapors -1

2 Review of rganic hemistry hemistry of the compounds of carbon Number of organic compounds exceeds 8 million Number of inorganic compounds is about 300,000 haracteristics of the arbon Atom Atomic number = 6 Atomic weight = 1 Total electrons = 6 Valence electrons = 4 Forms covalent bonds Single Double Triple Molecular, Structural and Semi-Structural Structural Formulas Molecular Formula 6 Structural Formula Semi-structural Formula 3 3 -

3 ydrocarbons ompounds formed only from carbon and hydrogen Alkanes Alkenes Alkynes yclic compounds Alkanes arbon atoms linked only by single bonds General formula: n n+ Methane ( 4 )) Ethane ( 6 ) Propane ( 3 8 )) Butane ( 4 10 )) Pentane ( ) Isomers of Butane (a) n-butane (b) i-butane i -3

4 Isomers ompounds with the same molecular formulas, but with different structures All alkanes with four or more carbon atoms exist as isomers Alkanes with five or more carbon atoms exist as more than two isomers Alkenes ydrocarbons that contain one double bond General formula: n n Ethylene ( 4 ) Propylene ( 3 6 ) Butylene ( 4 8 ) Pentylene ( 5 10 ) Diolefin ompounds Molecular Formula Name Structural Formula Semi-structural Formula 46 butadiene 58 -methyl butadiene 3-4

5 Butylene Isomers (a) (b) Alkynes ydrocarbons that contain one triple bond General formula: n n- Ethyne ( )) Propyne ( 3 4 ) Butyne ( 4 6 )) Pentyne ( 5 )) 8 yclic ompounds ycloparaffins Aromatic hydrocarbons -5

6 -6 Examples of Examples of ycloparaffin ycloparaffin ompounds ompounds yclopentane yclopropane yclohexane yclobutane Benzene Structure Benzene Structure (b) (a) Biphenyl Biphenyl

7 Benzo () pyrene Nomenclature 1 carbon carbons 3 carbons 4 carbons 5 carbons 6 carbons 7 carbons 8 carbons meth- eth-- prop- but- pent- hex- hep- oct methane ethane propane butane pentane hexane heptane octane Functional Groups Alcohols Amines Mercaptans hlorides -- --N --S -l -7

8 Location of Substitution 1,1,1-trichloroethane -propylamine 1,1,,-tetrachloroethylene Perchloroethylene Functional Groups ontaining xygen -8

9 ommon Alcohols Methylalcohol Ethylalcohol Isopropyl alcohol (Isopropanol ) n-propyl alcohol Phenols 3 3 Phenol rtho-cresol (o-cresol) Meta- cresol (m-cresol) Polyhydric Alcohols Ethylene glycol Glycerol -9

10 Ether ompounds Diethyl ether Methyl ethyl ether yclic Ethers 3 Ethylene oxide Propylene oxide -10

11 Aldehydes Formaldehyde 3 Acetaldehyde = Acrolein -11

12 Ketones Acetone Methyl ethyl ketone (MEK) Acids 3 R Formic acid (a) Acetic acid (b) Peroxyacids (c) -1

13 Acid Anhydrides R R 3 3 Representation of an acid anhydride (a ) Acetic anhydride (b) Maleic anhydride (c) Ethyl Acetate

14 rganic ompounds ontaining alides rganic hlorides hlorides of methane and ethane l l l l l l l l l l l l Methylene chloride hloroform arbon tetrachloride Methyl chloroform (1,1,1 - trichloroethane) rganic hlorides (continued) hlorides of ethylene l l l = l = l = l l l l = l l = l Vinyl chlori de (ch lor oet hen e) Vin ylide ne chl oride Et hylen e dich lorid e Trich loro eth ylene Perc hlor oet hylen e -14

15 rganic hlorides (continued) ther double-bonded chlorides l = l = = Allyl chloride hloroprene rganic hlorides (continued) l hlorobenzene hloridesof benzene l l l Benzylchloride p-dichlorobenzene l l l l Example of a polychlorinated biphenyl (PB) hlorofluorocarbons l l F l l F F F l F l l F l Trichlorofluormethane (Freon 11) Dichlorodifluoromethane (Freon 1) Trichlorotrifluoroethane (Freon 13) -15

16 ompounds ontaining Both xygen and hlorine l l Phosgene (a) l Epichlorohydri n (b) l l l l Di oxi n (TDD),3,7,8, tetrachlorodibenzo-p-dioxin (c) rganic ompounds ontaining Nitrogen PAN and PBN ompounds 3 N 65 N Peroxyacetyl nitrate Peroxybenzoyl nitrate -16

17 rganic ompounds ontaining Nitrogen Amine ompounds Primary amine: RN 3 N Secondary amine: R N 3 N 5 Tertiary amine: R 3 N ( 5 )) 3 N rganic ompounds ontaining Sulfur Methyl mercaptan Dimethyl sulfide 3 S 3 S 3-17

18 Formation of zone and Photochemical Smog Photochemical Reactions h * A A A * B... Wavelengths of interest are 80 nm to 730 nm Variables Affecting Intensity Latitude Time of day Time of year Presence of clouds or aerosols Summer maximum = x photons cm sec -1 for hours Winter values = x photons cm - - sec -1 for hours -18

19 Energy Absorbing Molecules N 3 N Aldehydes Ketones Basic Photochemical ycle N h N M 3 3 N N Role of Vs 3 h * * Understanding reactions is key -19

20 Reactions of Formaldehyde Photolysis: h Reaction with : Reactions of Formaldehyde (cont d) M Reactions of Formaldehyde (cont d) N N N N 3-0

21 Reactions of Acetaldehyde Photolysis: h 3 3 Reaction with : 3 3 Reactions of Acetaldehyde (cont d) N N 3 3 Reactions of Acetaldehyde (cont d) N N N 3N -1

22 Summary N h N M 3 3 h * * Photolysis of Aldehydes R hν R R R Reaction of with Aldehydes R R R R R N N R R R R R -

23 Reaction of with ydrocarbons R R R R R N N R R N RN R R N N Properties of rganic Vapors Gas and vapor definitions Molecular weight and the mole Equation of state Vapor pressure Partial pressure and partial volume oncentration expressions Explosive limits Gas and Vapor Definitions A gaseous material below its critical temperature is a vapor. ompressing a vapor at constant temperature will cause it to condense. A gaseous material above its critical temperature is a gas. ompressing a gas at constant temperature will not cause it to condense. -3

24 Molecular Weight Molecular weight is the sum of the atomic weights of all atoms in a molecule MW mixture MW n i1 i = mole fraction of component I MW i = molecular weight of component i i i The Mole A mole is a mass of material that contains a certain number of molecules. It is numerically equal to the molecular weight. The gram-molemole is the mass of material that contains Avogadro s number of molecules. The ideal gas law: Equation of State PV = nrt P = absolute pressure V = gas volume n = number of moles R = constant T = absolute temperature -4

25 Values for R psia-ft 3 /lb-mole mole- R 0.73 atm-ft 3 /lb-mole mole- R 8.06 atm-cm 3 /g-mole mole-k 8.31 x 10 3 kpa-m 3 /kg-mole mole-k Volume orrection PV nr NSTANT(if n NSTANT) T P1V 1 T 1 PV T P V1 V P 1 T T 1 Molar Volume V RT n P At 68 FF and 1 atm: V n 3 atm ft R RT lbmole R P 1atm ft lbmole 3-5

26 Gas Density m PV RT MW m P MW V RT Antoine equation: Vapor Pressure B ln( p * ) A T p* = vapor pressure T = temperature A,B, = constants Partial Pressure Dalton stated that the total pressure of a gas mixture is the sum of the individual pressures of each component p P i T n n i T -6

27 Partial Volume Amagat stated that the total volume of a gas mixture is the sum of the individual volumes of each component i n V n T i T p P i T n n i T i V T oncentration Expressions Partial pressure Parts per million by volume (ppmv) ppmv Mass per unit volume i 6 i x10 V T -7

28 onversion Equation 3 1ft V 1 ppmv ft V lb mole V MW 3 ft V 1 V molar lb V lb molev MW 1ppmv V V 6 molarx 10 lb V ft 3 Explosive Limits LEL is the concentration of V below which combustion will not be self- sustaining UEL is the concentration of V that produces a non-burning mixture because of the lack of oxygen Explosive Limits of Selected Vs Explosive Limit (Volume %) Substance Lower Upper Methane n-exane Ethylene Toluene Xylene Methanol Ethanol Gasoline