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Unformatted text preview: 13.7 (also available as a Mathcad worksheet)
“C32 : ,Vng
“casz {Vs} Species balance table: . Since "C : 1 (solid), and P : 1 bar : standard state pressure. Species Initial Final yi K3 : X f (1 7 X)
C i i i 52 1 17 X (1 — X) :> or (:52 0 X X X=Ka/(1+Ka) 1 Using CHEMEQ I ﬁnd K3050D C) : 8.478 and Ka(1000° C) : 6.607 . Therefore
X(750D C) : 0.894 and X(1000° C) : 0.869 . X : yc52 is the percentage equilibrium conversion of sulfur. 13.4
A G0 7
Kg : exp — "m : exp —2866 : 0.3147
RT 8.314X298.15
. [P V,
: “ma ; where ai : L : exp{ ’1 (P71bar)}
gimme )2 (1:13 :1bar) RT TPoynﬁng correction
terms assumed
inmmpressible solid adiamoud : expiZdJm (13,1 bar)/RT} : 6Xp{(zdjm 7 [£02, 1 bar)} 57mph“,a exp{Zy(P—1bar)/RT} RT
where
76m :lzg—m:3.4188 cc/mol:3.4188x104 ms/mol
3.51 g/cc
7 a h :ug—ll'm’l: 5.3333 cc/mol: 5.3333x10’6 m3/mol
grp 2.25 g/cc
34188—53333 P—l cc—bar 7A 6° 4
m0.3147:( X ) : "m— : 2866 J/mol
RT RT R
2P7] bar: 2866 “”101 :1497.0 J/cc:14970 bar 1.9145 cc/mol or P: 14971 bar.
Thus for P < 14971 bar ; 0‘11"“ > K“ and graphite is stable phase for P > 14971 bar ; 0‘11”“ < Ka and diamond is stable phase
"mph
:> Need a hydraulic press capable of exerting 14971 bar to convert pencil leads to
diamonds. (Also, should consider a higher temperature!) 13.20 Using the data in the problem statement, Tables 3.4 and Appendix AIV, I ﬁnd a  a P
Kama K) — “5‘02 C02 — 148.1 — am: — yco, , (1)
IQCalooﬂsro, 1 bar
since the activity of all the solids are unity.
3
a ' a a
Kagoso K) — 5‘302 F3304 0° — 0.0277 — ”CO — yco , (2)
arage51025111302 aco2 J’co2
and
a a3 1,12
K0 (750192M203973x1014 2;: lb”
,3 3 _ 1,12 ' 1,12 P
a1105102130, “0, y 02
P
:> yo! = 1.242 ><1()_28 (3)
1 bar From eqn. (2) we have yco ~ 0.0277 , while from spectroscopic observations yoo E 10—4 yoo, J’co2 Also, ﬁ‘om eqn. (1), P002 ~148 bar , while ﬁ‘om the probe, the total atmospheric pressure is only between '15 and 105 bar. Finally, ﬁ‘om Eqn. (3), we conclude there is no 02 in the atmosphere, compared to a trace from spectroscopic observations.
Conclusions? Somewhat ambiguous!
Calculations and data are not in quantitative agreement, but are certainly in qualitative agreement. Consider the uncertainty in all the measurements, the atmospheric model is undoubtedly a
reasonable one, and can not be rejected. ...
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 Spring '11
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