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Unformatted text preview: _ . . Ike following problems are ﬁom previous exams in this class. We will work them out during
recitation today and show solutions. These problems do not have to be handed in. Problem 1 {suggested time: 15 minutes} A liquid mixture containing 30.0 mol% benzene (B). 25.0% mol% toluane (T). and the balance
xylene (X) is fed to a distillation column. The bottoms product contains 96.0% X and no B, and
95.0% of the X in the feed is recovered in this stream. The overhead product is fed to a second
column. The overhead product from the second column contains 97.0% of the B in the feed to
this column. The composition of this stream is 94.0 mol% B and the balance T. A) Fill in the missing arrows and label (including units) knowns and unknowns in the ﬂowchart
below. Be sure to use the minimum number of unknowns in labeling your ﬂowchart (based
on the information above). H1 mot/la 3‘11; moi/l.
1,30 mom Column 1 X32 mo: 8 in”: Column 2 n _ 9.4 m“ g/mel.
_.._..—) 371. ml The“ 0.06 Mot T/mm‘ 0.300 mol Eltmol 0.250 mol Ttmol ’"x€a“l‘rz "M “M” 0.450 mol Xtmol
Minot/g. fl; Mol {h
0.0% luv'T'hunl V Ass ml 5/M0l
0% met Mme] X75 M°i T/mel . has. xﬁ mot xtmnl
B) Do a degree ofﬁeeclom analysis ofthis problem to prove that for an assumed basis of
calculation, molar ﬂow rates and compositicms of all process streams can be calculated from
the given information. (Hint: do an analysis of column 1 ﬁrst. Then do an analysis of
column 2 based on column 1). Column 1 Column 2.
4 H’LWJ (LL: “'5! x81. , KT}. Afarlﬁmws m“ ns‘ X'gf KT:
“3 Ewimurl (no Kg”) '— animag (Hofxm) _ l Speciﬁcaan (iSZWoFx} — i SP“ (ﬁgmenn) .—._._, 0:1‘iDF C) Write down in order, the equations you would solve to calculate unknown process variables.
For each equation, 0t: pair of simultaneous equations, circle the variable for which you would
solve, Do not do the calculations. (Hint: start with equation with fewest unknowns.) Cblumn } a7 972Wvﬁg 0.97xﬂ1n1203m, a) «(21' H1 *3 n“; + @145 EngrD 219  Prelim l Initials 2. 40 int5' este ‘ e'30 minute The following two reactions occur simultaneously: FcS: + 30, —I> FeO(J} +280,(g) Reactionl ll .52. 21TeS2 + 30, > Fe,OJ{s) + 4SO,(g} ReacﬁonZ The product gas (ﬂue gas) consists of 10.2 mol% 50;, 7.8 mol% 0;, and 82.0 mol% Hg. The feed is PBS;
and air. (3) Draw a proper flow chart for this process. Take as a basis 100 mol of prﬂuct gﬁ.
LAKE? Emu: ’ and 24%.“ 1942! mot»:st WIIJM w mom Q {Auk WW.
Fes (coma!
0;,”an 2' meme. ) n01 ml 02_ 101?. w! 25oz loam/$01
£'°”°"‘3' “3 £1.0m3/N1. "him; 1:910 {53 O [S "5103!"?! a: 3 J (b) Deﬁning extents of reaction {1 and £2, write formulas in terms of The extents of reaction for the number of
moles of each component in the product gas. EngrD 219 — Prelim l Initials (c) Find the extents of reaction. 6J4: hm Hal)" ilk 6nd Lek/5L. ﬁ~l30 : Home : ($991: 21.3mmoz fo+9£2=im2 =3) f,=S.!—Q£L
239 "$725; "ff/251519 )
i__ ________,_,_____——u “S72 (S‘.I—Q£1,)'H/1(§1‘ "'5‘
:'2.75.+.S;L ”4.£1.= in; —’4 £1, = 4.35" I! €z: lugmob} ?
{.1‘ IKES) = ’OJMOL’IJ ——____. a"; H (d) How many moles ofFeS: reacted by reaction 1 and how many moles of RS; reacted by reaction 2‘? nFefq. = nch,» _ 15’ _ 262‘ 1‘ f
0.1 l"
more “HM
rum nm 1 ’2. EngTD 219 — Prelim 1 Initials (e) Use atomic balances to ﬁnd the number of moles of FeO and F8203 formed. You can do this even ifyou
are unsure of your answer to part (c). Otherwise, show your results are consistent with your answers to
parts (c). *1. 5:57. .9 I" ‘ __ _"___) imam: In}, 1.1M!!! 01,
2!: I" 01. “mo! N1.
#1., WIN1. HL Me}. Fca “'3
#11, Mo! Pa 93“) Fe: n1: I01, + 710:
0. 2n”) = n; 4 3n; + 2H“) 4 2mg)
5 2.14; a “7 Z ...
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 Spring '08
 HINES, M

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