Physical Constants Other Units Important Equations R    = 8.314 J mol-1 K-1      = 0.08206 L atmK-1 mol-1    = 0.08314 L bar K-1 mol-1 NA = 6.022 x 1023 mol-1 kB    = 1.381 x 10-23 J K-1 h    = 6.626 x 10-34 J s F    = 96,500 C mol-1 c    = 2.998 x 108 m s-1 g    = 9.81 m s-2 B    = 0.51mol-1/2dm3/2 (in H2O, 25oC)   Sequential reactions: [B]=(k1/(k2-k-1)) f(t)[A]0  f(t)=exp(-k1t)-exp(-k2t)   Parallel reactions: Φi = ki/S Where S is the sum of all rate constants of the paral-lel reactionsNote: Quantum yield/efficiency = Φ = moles of product formed / moles of photons absorbed 1dm3   = 1 L 1dm3   = 1000 cm3 1 J    = 1 kg m2 s-2 1 atm    = 1.101325 x 105 Pa 1 atm    = 760 mmHg 1 Torr = 1 mmHg  1 Torr = 133.322 Pa 1 bar    = 105 Pa 1 nm    = 10-9 m   Eyring equation: k =kBT/(hc0) x f f =exp(ΔS#/R) x x exp(-ΔH#/RT)   ln(1 - θ) = -θ if θ << 1 E   = hυ c   =υλ  PV =nRT ΔG = ΔH - TΔS  k = A k    = A = e (kBT/h) exp (Δ‡S/R)k    = Ea = Δ≠Ho-PΔ≠Vo + RT (sol)    = Δ≠Ho-ΣνRT + RT (gas) log k = log ko+ 1.02 zAzB log k = log ko - ΔGo = - RT ln Kc  υ =  θ = KP/(1 + KP), at T=const tf = (kf +kq[Q])-1,    Q is quencher

1.
Find the correct choice: The Transition State in a reaction …
 A. … must have at least one weak bond.
 B. … can have only strong bonds.
 C. … is a stable molecule.
 D. … is at a minimum of the potential energy diagram.
 E. … is a stable intermediate.

2.
At equilibrium,
 A. forward and backward reaction rates are equal.
 B. all rates are zero.
 C. the backward reaction is faster than the forward reaction.
 D. forward and backward rates are not equal.
 E. reactant concentrations are zero.

3.
For the parallel reactions
 A → BA → CA → D rate constant k1rate constant k2 = 2.3 k1rate constant k3 = 4.0 k1

What is the yield of C?
 A. 31.5%
 B. 13.7%
 C. 54.8%
 D. 45.2%
 E. 86.3%

4.
Two reactions follow the Arrhenius law and have the same pre-exponential factor. If the activation energy of reaction (1) is 20 J/mol and that of reaction (2) is 200 J/mol, what would be their rate constant ratio (k1/k2) at 300K?
 A. 1.075
 B. 0.93
 C. 1.083
 D. 0.922
 E. 1.037

5.
For the reaction mechanism
 A → II → P rate constant k1rate constant k2

 A. k1[A] – k2[I] = 0
 B. k1[A] + k2[I] = 0
 C. k1[A] = 0
 D. k2[I] = 0
 E. d[P]/dt = k2[I]

6.
In the mechanism,
 (1)      2{ N2O5(2)          NO2 + NO3(3)          NO + NO3 →→ NO2 + NO3}NO + O2 + NO22 NO2 equilibrium

for the decomposition of into and ,
 A. both and are intermediates.
 B. only is an intermediate.
 C. only is an intermediate.
 D. only is a catalyst.
 E. both and are catalysts.

7.
A possible mechanism for the reaction, 2A + B C + D, is:
 A + A A2 fast, equilibrium A2 + A A3 slow A3 + B A + C + D Fast

According to this mechanism, the rate law (rate of formation of one of the final products) will be (k is an effective rate constant keff):
 A. Rate = k[A] 3
 B. Rate = k[A][B]
 C. Rate = k[A] 2 [B]
 D. Rate = k[A]
 E. Rate = k[A ] 2

8.
The decomposition of hydrogen peroxide (substrate ) is catalyzed by the enzyme catalase ( ). At an initial catalase concentration [So] of the variation of (the reciprocal of the initial rate) with (the reciprocal of the initial concentration of the substrate) is given by (Lineweaver-Burk equation),
(1/R0) = 0.6977 s (1/[S]0) + 26.557 s/M

based on this experimental result, which one of the following choices is correct?
(left to right: Maximum rate in M/s, Michaelis constant in M, and the turnover number in 1/s)
 A. 3.77 x 10-2,      2.63 x 10-2,      1.08 x 107
 B. 2.63 x 10-2,      3.77 x 10-2,      7.51 x 106
 C. 0.6977,            26.557,           1.08 x 107
 D. 26.557,            0.6977,           1.08 x 107
 E. 3.77 x 10-2,      2.63 x 10-2,     7.51 x 106

9.
The adsorption of Kr on charcoal at 193.5 K , closely follows the Langmuir adsorption isotherm and in turn the linear relation,

(1/Vads) = 0.34076 (torr g/cm3) x (1/P) + 0.03258 g/cm3
where is the volume of Kr adsorbed per gram charcoal at the equilibrium Kr pressure, . Which one of the following choices is correct (left to right: Volume of Ar needed to form a monolayer per gram charcoal, , and the adsorption equilibrium constant in torr-1 at 193.5 K)?
 A. 30.7,              9.56 x 10-2
 B. 30.7,              2.93
 C. 2.93,              30.7
 D. 28.7,              0.341
 E. 9.56 x 10-2,    28.7

10.
The mechanism suggested for the reaction,
2 A + B → 2 C
is,
 A + A I forward rate constant k1, backward rate constant k-1 I + B    → 2 C constant k2

The rate law obtained on applying the steady state approximation is,
 A. Rate = k1k2[A]2[B]/(k-1 + k2[B])
 B. Rate = k1k2[A]2/(k-1 + k2[B])
 C. Rate = k1k2[A]2[B]
 D. Rate = k1k2[A]2[B]/(k1 + k2[B])
 E. Rate = k1k2[A][B]

11.
Using the following graphs, which one shows the rate of change of H2O2 with time (assume the reaction to be an elementary one)?
2 H2O2(l) → 2H2O(l) + O2(g)
 A. B. C. D. 12.
Consider the following reaction:
C2H8(g) + 4O2(g) → 2CO2(g) + 4H2O(g)

If 1.0 mol C2H8 is consumed in 4.0 min, the rate of H2O production in mol/min is
 A. 1
 B. 4
 C. 0.25
 D. 4
 E. 8

13.
A second order reaction with initial reactant concentration of 0.80 M has a rate constant of 0.05 M-1s-1. How long will it take in seconds for the reactant to lose 50% of the initial concentration?
 A. 25
 B. 50
 C. 10
 D. 125
 E. 8

14.
Consider the following reaction: The relationship of the rate of appearance of B and the rate of disappearance of A is:
(Δ[B]/Δt) = C x {- Δ[A]/Δt)}
The factor C is
 A. 0.667
 B. -2/3
 C. 0.334
 D. +1
 E. +3/2

15.
Determine the rate expression for the following reaction:
2MnO4-(aq) + 6H+(aq) + 5ClO3-(aq) → 2Mn2+(aq) + 3H2O(l) + 5ClO4-(aq)
 [MnO4-]/M [ClO3-]/M [H+]/M Initial Rate Ms-1 0.10 0,10 0.10 5.2x10-3 0.25 0.10 0.10 3.3x10-2 0.10 0.30 0.10 1.6x10-2 0.10 0.10 0.20 7.4x10-3

 A. k[MnO4-]2[ClO3-][H+]1/2
 B. k[MnO4-][ClO3-] 1/2 [H+]2
 C. k[MnO4-]1/2[ClO3-][H+]2
 D. k[MnO4-][ClO3-][H+]2
 E. k[MnO4-]2[H+]1/2

16.
The mechanism of the chain reaction C2H6 C2H4 + H2 is: The reactive intermediates of the mechanism are the species:
 A. H, CH3 and C2H5
 B. H, CH4 and C4H10
 C. H, CH3 and C4H10
 D. CH3, CH4 and C2H5
 E. H, CH4 and C2H5

17.
The gas-phase chain mechanism of the reaction Cl2 + CH4 → CH3Cl + +HCl is: The overall rate of reaction in terms of the rate of formation of HCl is (keff: is an effective rate constant)
 A. keff [Cl2]1/2[CH4]
 B. keff [Cl2][CH4]1/2
 C. keff [Cl2]1/2[CH3Cl]
 D. keff [Cl2] [CH3Cl]1/2
 E. keff [CH4][CH3Cl]

18.
If τf = 1 x 10-10 s and kic = 5 x 108 s-1, what is Φf? Assume that the rate constants for intersystem crossing and quenching are sufficiently small that these processes can be neglected.
 A. 0.95
 B. 0.81
 C. 0.62
 D. 0.27
 E. 0.77

19.
The chlorination reaction of ethane (Cl2 + H3CCH3 ◊ ClH2CCH2Cl + H2) processes via a chain reaction mechanism. Which one of the following is not a chain propagation reaction in the chlorination of ethane?
 A. Cl + Cl Cl2
 B. Cl + H3CCH3 ClH2CCH3 + H
 C. Cl + H3CCH3 H3CCH2 + HCl
 D. H + Cl2 HCl + Cl
 E. Cl2 + H2CCH3 ClH2CCH3 + Cl

20.
A reactant can be photo-chemically converted to a cis-product. In an experiment, 4.15 mmol of reactant are converted when irradiated with 100. W of 280. nm light for 27.0 s. All of the light is absorbed by the sample. What is the overall quantum yield for this photochemical process?
 A. 0.66
 B. 0.4
 C. 0.1
 D. 0.78
 E. 0.21 This is the end of the test. When you have completed all the questions and reviewed your answers, press the button below to grade the test.