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Lecture17

# Lecture17 - ChE 210 Meeting 17 Outline(F&R Sections...

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Unformatted text preview: ChE 210: Meeting 17 February 21, 2011 Outline (F&R Sections 6.0-6.2) Homework Due Friday 02/25/2011 - Phase Diagrams 5.12, 5.16, 5.25, 5.30, 5.69, 5.74 - Vapor Pressure - Gibbs Phase Rule Phase Diagrams Pressure ) , T. 19‘ 'P ' ‘m Tempé‘tature Critical temperature (Tc) — the highest temperature at which a substance can coexist in two phases Critical pressure (Pc) — the pressure required to form a drop of liquid at the critical temperature Solid -— a substance that retains a deﬁnite size and shape, and does not ﬂow under stress Liquid - a ﬂuid that has no independent shape but has a deﬁnite volume, does not expand indeﬁnitely and is only slightly compressible Vapor - a ﬂuid that exists below the critical temperature of the substance and has neither independent shape nor volume but tends to expand indefinitely (vapors can be compressed to form a liquid) Gas - a fluid that exists above the critical temperature of the substance and has neither independent shape nor volume but tends to expand indeﬁnitely (gases cannot be compressed to form a liquid) Vapor pressure (p*) — the pressure of a substance at a temperature T where a vapor and liquid (or a vapor and solid) coexist Boiling point temperature (TB) — the temperature of a substance at pressure P where a vapor and liquid coexist 1/4 ChE 210: Meeting 17 February 21, 2011 Normal boiling point - the boiling point temperature of a substance when the pressure is equal to 1 atm ”ﬁlth/(Hal m {:1 Melting point or freezing point (TM) — the temperature of a substance at pressure P where a solid and liquid coexist Sublimation point (Ts) — the temperature of a substance at pressure P where a solid and vapor coexist Triple point - the temperature and pressure of a substance where all three phases (solid, liquid and vapor) coexist Estimation of Vapor Pressure - Vapor pressure (p*) is a function of T . Often data is not available at T of interest 1-7" mead .3 L?r7’€/(,.H7Q”1;§ dp* AHV Clapeyron equation: A A T Vg—VL 7 is Lﬁle/‘m‘ﬁ’ wnliocyzmue l‘ f\ : », 4 Vi ' ’_ 31““? .f A; .h‘ , l, n t ' .n , — VJ WM» L Wt) «(101% va‘u‘ng (J; LAG) de Luanda; ‘ mad he Vélfh’r Am 1 lootem heat of witpm Z’Cl‘t'lcfx ")C’WC;§7 TQé‘dU/Ed ﬁg» l/(QCYJFV‘ .7113 If!) L"‘/€ 070 C. T? (20 d I 2/4 ChE 210: Meeting 17 February 21, 2011 A A A *Unless P is very high, V|_ << V9 and V9 a El:- for an ideal gas d(|np *) = "AHv 1 ) R d(/T 1mm pm 1,1,0! vs ‘/7 119a AHV ‘4 AH», I5 iﬂbLl/Q‘P‘L’o/ “IQJ’ many W)3}Qn(3&‘ CIausius—Clapeyron equation: lnp* = _:I_:V + B xx 1‘?“ Aﬁv r» Qmsmm Gvé'r ‘T ruﬁtga a e) is \$1.th 23990490 -9 1F {3* 13 known at Si‘lﬁ‘n “T, B can be Caidecried Hm “393 *0 cal (“Mickie f“ a} miner T B T+C Antoine equation: logp * = A — -—> 0003mm H, 6 am C we iaimdcﬁred m Em " b2 (WE-ﬂu“ wHJn Emits 1% A16 and C XCiJLU’SG Clr‘JL/ memod Hy CaiCLUC‘thy [5‘1 W ,5 QCCLLﬂ'fC”. Cave,» '7- range of [Merésﬂ 3/4 ChE 210: Meeting 17 February 21, 2011 Gibbs Phase Rule Phase equilibrium means T1 = T2, P1 = P2 and composition of phases does not change with time . Extensive variables — depend on the size of the system ('/r)(:253, v’otumc“) - Intensive variables — independent of the size of the system (T, f’, p, v, x; 3;) Gibbs Phase Rule relates the number of intensive variables that can be independently specified to the number of species and phases Xda’ Omar /rh‘€/15/vt variabltis (an m (rd: gunned] ﬁrm? #7636 Vang/7165 DF = 2 + C — 11 <—— #lgnrue; are rte; er /’ ¢ h/tjedo. .‘n # Jk'mﬂ 1/ d, A}! , . SPEC/CS! U Viz/labe'} #221} can a; 23/960566 Examples: Pure liquid water ( <3 = / TI“ / ) DF= 571+ i~/ = <51 Mixture of solid, liquid and vapor water ( c = / 77 = 3 ) Dir-'52 * I r 3 : O *m {77,0ch porn-2f Vapor-liquid mixture of acetone and methylethylketone ("a =0? 77*: a) DI:: (if.§‘13q :91 1 *Szfﬁhg 7' and .ﬂ {Meg cam/3o; hawk 3 J m, Cor xzszhcyl hxés amt 1” e 75 N 4/4 ...
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