Thermodynamc Prncples Envronmental Oranc Chemstry ESE-CH 176 04-04-18
Chemcal Potental What s chemcal potental? J.W. Gbbs Chemcal potental s the Gbbs free enery added for each added mole of a component () of the system é ê ë G n ù ú û T, Pn, j¹ º µ -1 (kj mol )
Glbert N. Lews Fuacty A measure of chemcal potental A tendency to flee A chane n chemcal potental related to a chane n vapor pressure (dp ) ( dµ ) = V dp T n Fuacty s a measure of a chemcal potental n the form of 'adjusted pressure'. It reflects the tendency of a substance to prefer one phase (lqud, sold, or as) over another, and can be lterally defned as the tendency to flee or escape. The phase wth the lowest fuacty wll be the most favorable, and wll have the lowest Gbbs free enery. Fuacty s expressed n unts of pressure. 1 atm = 101,325 Pa 1.01325 bar 760 torr
Fuacty s a state functon of matter at a fxed temperature. It only becomes useful when dealn wth substances other than an deal as. For an deal as, fuacty s equal to vapor pressure. Under low pressures and hh temperatures some substances approach deal behavor, no substance s truly deal, so fuacty s used to descrbe non-deal ases, lquds and solds.
é G ù ê ú ë n û T, Pn, j¹ º µ -1 (kj mol ) ( dµ ) = V dp T n
Fuacty of Gases Assumn an deal as V PV = nrt = n Interatn wth respect to a defned standard state (e..,! 0, P 0 ): RT P ( dµ ) = V dp T n é P ù = 0 + RT ln ê ú P 0 ë û µ µ
Fuacty of Gases For non-deal ases (hher concentratons, ntermolecular nteractons) and as mxtures é f ù = 0 + RT ln ê ú f 0 ë û µ µ For an deal as 0 lm 1 P = f P
Fuacty of Gases Ideal as: f = P Non-deal as: f =q P Ideal as mxture: f = xp Non-deal as mxture: f =q xp
Fuacty of Lquds Ideal lqud: f = P l 0 () Non-deal lqud: f = P l 0 () Ideal lqud mxture: f = xp l 0 () Non-deal lqud mxture: f = xp l 0 ()
Molecular formula CCl 4 Molar mass 153.82 /mol Appearance colorless lqud ether-lke odor 1.5867 /cm 3, lqud Densty 1.831.cm -3 at -186 C (sold) 1.809.cm -3 at -80 C (sold) Meltn pont -22.92 C (250 K) Boln pont 76.72 C (350 K) Solublty n water 785 800 m L -1 at 25 C Solublty soluble n alcohol, ether, chloroform, benzene lo K OW 2.64 Vapor pressure 11.94 kpa at 20 C Refractve ndex (n D ) 1.4601
Fuacty of Solds Ideal sold: Non-deal sold: Ideal sold mxture: Non-deal sold mxture: f = P s f = P s 0 () 0 () f = xp s 0 () f = xp s 0 ()
Substance P v (Pa) P v (bar) P v (mmh) T ( C) Tunsten 100 Pa 0.001 0.75 3203 Ethylene lycol 0.5 kpa 0.005 3.75 20 Propanol 2.4 kpa 0.024 18.0 20 Water 2.4 kpa 0.024 18.0 20 Ethanol 9 kpa 0.09 67.5 20 Methyl sobutyl ketone 26.48 kpa 0.02648 19.86 25 Freon 113 37.9 kpa 0.379 284 20 Acetaldehyde 98.7 kpa 0.987 740 20 Helum 100 kpa 1 750-269.15 Butane 220 kpa 2.2 1650 20 Formaldehyde 435.7 kpa 4.357 3268 20 Carbonyl sulfde 1.255 MPa 12.55 9412 20 Propane 2.2 MPa 22 16500 55 Oxyen 54.2 MPa 542 407936 20 Ntroen 63.2 MPa 632 475106 20
Propertes Molecular formula C 12 H 4 Cl 4 O 2 Molar mass 321.97 /mol Densty 1.8 cm 3 Meltn pont 305 C, 578 K, 581 F lo K o/w 6.8 Vapor pressure 2,3,7,8-Tetrachlorodbenzodoxn 1.5 10 9 mm H
Vktor Yushchenko, Former Presdent of the Ukrane, Posoned wth Doxn durn Electon Campan October 2004
Germany has had to halt sales of poultry pork and es from more than 4,700 farms after anmal feed was found to contan doxns. The anmal feed 'contaned 78 tmes approved amount of doxn reported on 01-07-11
Polydmethylsloxane (PDMS) S(CH ) Cl + n H O [S(CH ) O] + 2n HCl 3 2 2 2 3 2 n
Global concentratons of cyclc volatle methyl sloxanes (n/m 3 ). Global concentratons of lnear volatle methyl sloxanes (n/m 3 ).
Sold Gas Vapor Pressure p-dchlorobenzene napthalene 1,4-Dchlorobenzene (paradchlorobenzene, p-dcb, PDB) s an oranc compound wth the formula C 6 H 4 Cl 2. Ths colourless sold has a stron odor. p-dcb s used a pestcde and a deodorant, most famously n mothballs n whch t s a replacement for the more tradtonal naphthalene. p-dcb s also used as a precursor n the producton of the polymer poly(p-phenylene sulfde).
1,4-dchlorobenzene 1,4-dchlorobenzene s used as an ar freshener, deodorzer n urnals and as a moth and brd repellent. In 1990, t was estmated that 3500 tons per year were ben used n Canada alone. Cl Cl - Lo P o = 2.8 (atm)
Napthalene Propertes Molecular formula C 10 H 8 Molar mass 128.17 mol -1 Appearance Densty 1.14 cm -3 Meltn pont Boln pont Whte sold crystals/flakes, stron odor 80.26 C, 353 K 218 C, 491 K Solublty n water 30 m L -1
Cedarwood (E)-5-(prop-1-enyl)benzo[d][1,3]doxole 4-Allyl-2-methoxyphenol 5-(2-propenyl)-1,3-benzodoxole (2R,4aR,8aS)-Decahydro-8-methylene- alpha,alpha,4a-trmethyl-2- naphthylmethanol
Reference and Standard States Gases: 0 é f ù é 0 f ù µ = µ + RT ln RT ln ê µ 0 ú = + ê ú ë f û êë f pure as úû 0 µ ln q = + RT [ x ] Lquds: Solds: é f ù µ = µ + RT ln = µ + RT ln x êë úû [ ] 0 0 ê ú f purelqud é f ù µ = µ + RT ln = µ + RT ln x êë úû [ ] 0 0 ê ú f pure sold
Non-dealty deal [ x ] = 0 + RT ln µ µ nondeal } a An deal soluton or deal mxture s a soluton n whch the enthalpy of soluton (or "enthalpy of mxn") s zero; the closer to zero the enthalpy of soluton s, the more "deal" the behavor of the soluton becomes. Lkewse, an deal mxture s one n whch the actvty coeffcents (whch measure devaton from dealty) are equal to one.
Attractve Forces van der Waals force Dpole dpole nteractons Hydroen bonds The reater the attractve forces between molecules, the hher s the boln pont of the compound
van der Waals Forces The boln pont of a compound ncreases wth the ncrease n van der Waals force
Dpole Dpole Interactons Dpole dpole nteractons are stroner than van der Waals force but weaker than onc or covalent bonds
Hydroen Bondn
Entropy of a molecule s ts freedom to twst and turn (orentaton) move electrons around ts structure (confuraton) be random n space (translaton) Enthalpy of a molecule s a measure of the molecule s attractons to ts surroundns (ntermolecular) tself (ntramolecular)
Phase Transfer Set chemcal potentals of compound n the two phases equal: A 1 A 2 é 0 f ù µ 1 1 = µ pure A + RT ln ê ú êë f pure úû é 0 f ù µ 2 2 = µ pure A + RT ln ê ú êë f pure úû f we set µ = µ (equlbrum), 1 2 f = f 1 2
Lqud to Ar Transfer Set fuactes of compound n the lqud and as equal: A lqud A as l xp l 0 () l = q xp A A A A A T q 1 l xp l 0 () l = xp A A A A T f lqud A =» f as l xp l 0 () l = P A A A A x P = xp A A T A n = A å n j j
In a small workshop at 25 o C, pant thnner s used to clean pant brushes Pant Thnner (a solvent) contans 1 vol% p-xylene n mneral sprts. Assumn that all of the pant thnner does not volatlze at equlbrum, what s the concentraton of p-xylene n the ar of workshop?
Model: Chem3D XML n Boln Pont = 421.471 Kelvn Crtcal Pressure = 35.856 Bar Crtcal Temperature = 636.244 Kelvn Crtcal Volume = 375.5 cm 3 /mol Gbbs Free Enery = 119.26 kj/mol Heat Of Formaton = 16.61 kj/mol Henry's Law Constant = 0.51 Ideal Gas Thermal Capacty = 131.214 J/(mol-K) Lo K ow = 3.15 Meltn Pont = 218.36 K Mol Refractvty = 36.14 cm 3 /mol Vapor Pressure = 1201.8 Pascal Water Solublty = 162.4 m/l
CAS Number : 000106-42-3 Chemcal Name : p-xylene Molecular Formula: C 8 H 10 Molecular Weht : 106.17 Meltn Pt : 13.2 C Boln Pt : 138.3 C Water Solublty:162 m/l or 1.53 10-5 M lo K ow (octanol-water): 3.15 Vapor Pressure: 8.84 mm H Henry's Law Constant: 0.0069 atm-m 3 /mole OH Rate Constant: 1.43 10-11 cm 3 /molecule-sec T = 298.15 K or 25 o C
lo P v p-xylene Vapor Pressure vs T T
P (mm H) 1 10 40 100 400 760 Example T n C 8.1 27.3 54.4 75.9 115.9 138.3 Acetone Naphtha Toluene p-xylene Methyl ethyl ketone (MEK) Dmethylformamde (DMF) Whte Sprts Turpentne
Solvent - Naptha Full rane naphtha s defned as the fracton of hydrocarbons n petroleum boln between 30 C and 200 C. It conssts of a complex mxture of hydrocarbon molecules enerally havn between 5 and 12 carbon atoms. It typcally consttutes 15 30% of crude ol, by weht. Lht naphtha s the fracton boln between 30 C and 90 C and conssts of molecules wth 5 6 carbon atoms. Heavy naphtha bols between 90 C and 200 C and conssts of molecules wth 6 12 carbons.
Lqud to Ar Transfer Set fuactes of compound n the lqud and as equal: A lqud A as l xp l 0 () l = q xp A A A A A T q 1 l xp l 0 () l = xp A A A A T f lqud A =» f as l xp l 0 () l = P A A A A P = xp A A T x A x l A n = A å n j j l na = å n j l j
p-xylene Vapor Concentraton? f l p-xyl = f p-xyl l x l P 0 () l = q x P p-xyl p-xyl p-xyl A p-xyl T q p-xyl» 1 l x l P 0 () l = x P p-xyl p-xyl p-xyl p-xyl T l x l P 0 () l = P p-xyl p-xyl p-xyl p-xyl l p - xyl l x p - xyl =??! 0.01 x l A l na = å n j l j
P 0 p-xyl () l Vapor Pressure vs. T 1 10 40 100 760 T 8.1 27.3 54.4 75.9 138.3 CAS Number: 106-42-3 Formula: C 8 H 10 CA Index Name: 1,4-dmethylbenzene P 0 p xyl ( l) == 7.94 torr - T = 25 C
Extreme Case Pure Lqud p-xylene P 0 p-xyl () l 0.010447 atm n/v = P/RT 0.000428 mol / L ar T 298 K R 0.082 L-atm mol -1 K -1 P 0 p-xyl () l 7.94 torr [p-xylene] 4.3 10-4 mol L -1 [p-xylene] 10447 ppmv
Actvty Coeffcents at Infnte Dluton of Alkanes, Alkenes, and Alkylbenzenes n 4-Methyl-n-butylpyrdnum Tetrafluoroborate T T T benzene 1.639 (313.68) 1.645 (322.99) 1.648 (333.36) 1.652 (343.79) toluene 2.632 (313.79) 2.652 (322.99) 2.671 (333.24) 2.688 (343.55) ethylbenzene 4.759 (313.69) 4.736 (322.99) 4.713 (333.24) 4.684 (343.55) o-xylene 3.683 (313.68) 3.716 (322.93) 3.739 (333.23) 3.762 (343.58) p-xylene 4.074 (313.72) 4.101 (323.47) 4.125 (333.25) 4.150 (343.57) m-xylene 4.454 (313.67) 4.455 (322.93) 4.456 (333.23) 4.458 (343.57) -propylbenzene 7.794 (313.73) 7.690 (322.94) 7.563 (333.23) 7.453 (343.58) t-butylbenzene 10.87 (313.73) 10.56 (322.95) 10.29 (333.23) 10.09 (343.58) T
p-xylene n the Workshop Ar atm ppmv P 0 p-xyl () l NA 0.010447 10447 1 0.000104 104 1.3 0.000136 136 5 0.000522 522 l p - xyl =?? x l p - xyl! 0.01