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Unformatted text preview: UNIVERSITY OF TORONTO ﬁ§,> FACULTY OF ARTS AND SCIENCE W, , CHM 220H1s P’s?)
AUGUST EXAMINATIONS, 2003 XX)
Duration — 3 Hours
Aids allowed: Unprogrammed Calculators NAME (print) Student No.
USEFUL DATA are attached at the back of the examination.
Wild STUDENT No. ON THISJAGE
The examination consists of eight question and they must be answered in the spaces provided on the test paper. Clear and concise answers are essential for full marks. Total marks = 80, which
will be converted to a mark out of 100. QUESTION No. MAXIMUM MARK STUDENT'S MARK
1 10
2 10
3 10
4 10
5 1o
6 10
7 10
8 10 TOTAL MARK: / 80 = % 2 1. One mole of an ideal gas at T1 = 298 K at a pressure of P1 = 1.00 atm is
compressed and heated to a ﬁnal temperature of T2 = 398 K and a pressure of
P2=100am1 (a) Calculate AE, AH and AS for this process. (b) Is AG = AH  TAS for this process? Why or why not? (c) Extra credit (5 points) Show that AG = 3R/2 (T2  T1) + 3R/2 (T1lnT1  T2nT2) + RT11n(P2/P1) conﬁnued 1.conﬁnued. conﬂnued 4 2. Liquids A and B form an ideal solution. Suppose the vapor pressure of pure
A is 66 Torr and the vapor pressure of pure B is 88 Torr at a temperature of
T = 45°C. (a) Calculate the composition of the solution (in mole fractions) if the mole
fractions ofA and B in the vapor phase above the solution are 0.4 and 0.6,
respectively. (b) Given that the molar enthalpies of vaporization of A and B are 30 kJ/mol and 40 kJ/mol, respectively, what would be the composition of the vapor in
mole fractions for a 1:1 solution of A and B at T = 50°C? conﬂnued 2.conﬂnued. conﬂnued 3. Consider the reaction at 25°C N2(9) + 3H2(9) ‘1 2NH3(Q) Suppose the initial partial pressures of the gases are: P(N2) = 1 atm, P(H2) = 2 atm and P(NH3) = 3 atm. (a) Is the initial system in equilibrium or does it evolve towards products or
reactants? (b) Estimate the highest temperature at which the system equilibrates in a state
in which the partial pressure of NH3 increases above its initial value of 3 atm.
Data: S°[N2(g)] = 192 J/(moI—K) S°[H2(g)] = 131 J/(moIK) S°[NH3(g)] = 193 J/(moIK) AHfO [NH3(g)] = 46 kJ/mol conﬁnued 3.conﬁnued. conﬁnued —8 4. Campers on a mountain at an altitude of 3000 m discover that their water
boils at 90°C instead of 100°C and it takes 200 minutes of cooking to make a
"three minute" egg. What is the approximate activation energy for the reaction
that occurs when an egg is cooked (denaturation of protein) in kJ/mole? conﬂnued 9 5. Concerning enzyme catalysis, what is meant by (a) Competitive inhibition ? (b) Noncompetitive inhibition ? (c) Uncompetitive inhibition ? (d) If you were to plot the reciprocal of the initial rate versus the reciprocal of
the substrate concentration with and without the inhibitor, how could you tell
whether the plot depicts a competitive or a noncompetitive inhibition ? conﬁnued 10 5.00nﬁnued. conﬁnued 11 6. What is the probability of finding the particle in the middle third of the box
(i.e. between a/3 and 2a/3) for a particle in a one dimensional box of length a for the n = 2 level.
tun = (2/a)"2 sin (nnx/a) ; fsinszdx = x/2  (sin2bx)/4b conﬂnued 12 7. (a) Sketch the radial distribution function, 4nr2[R(r)]2 versus r for a hydrogen
4d orbital. (b) Explain why the plot you have drawn in (a) is more informative than a plot
of [R(r)]2 versus r for the same 4d orbital. conﬁnued 13 8. (a) Assuming that the vibrations of a Cl2 molecule (where both of the atoms
are Cl35 isotopes) are equivalent to those of a harmonic oscillator with a force
constant of k = 330 Nm", what is the zeropoint energy for this molecule ? (b) Would this molecule absorb IR radiation ? Provide reasons for your answer. 14
Useful data and equations R = 8.3145 J/(molK) c = 3.00 x108 m/s U)» = 170 (f: frequency)
H=E+PV E=3/2nRT PV=nRT As = nR 1n Vz/Vl As = nCp 1n Tz/Tl AH = nCpAT AB = nCVAT AG = nRT 1n Pz/Pl AG = fS(T)dT 1n (lg/1),) =  (AHvap/R) (1/T2 — 1/T1) PA=XAP* PA=XAVP flnxdx =x1nxx —RT1nKp = ArG" ArG" = AH‘) — TArS" A,G = ArG" + RTan
111(k2/k1) = ' (Ea/R) (1/T2 ' l/Tl) I/u =1/m1+ 1/m2 Er: J(J+1)h2/81t21 v = (1/21c) (k/p)“2 Ev = (v + 1/2) hf (f = frequency) TOTAL PAGES = 14 ...
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