On the same axes, sketch the extent of reaction (p) vs time for (i) uncatalyzed and (ii) catalyzed condensation polymerizations. On a new set of axes, sketch the number-average molecular weight (Mn) vs time for (i) uncatalyzed and (ii) catalyzed condensation

On the same axes, sketch the extent of reaction (p) vs time for (i) uncatalyzed and (ii) catalyzed condensation polymerizations. On a new set of axes, sketch the number-average molecular weight (Mn) vs time for (i) uncatalyzed and (ii) catalyzed condensation

Chemistry: The Molecular Science

5th Edition

ISBN:9781285199047

Author:John W. Moore, Conrad L. Stanitski

Publisher:John W. Moore, Conrad L. Stanitski

Chapter11: Chemical Kinetics: Rates Of Reactions

Section: Chapter Questions

Problem 83QRT

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Living chain polymerization of monomer X follows the first-order kinetics. The corresponding propagation rate constant (kp) was determined by gas chromatography (GC), with the following monomer concentrations measured at different polymerization times, assuming instant initiation: Polymerization time (min) 0 2 5 10 15 [X]t (M) 1.80 1.52 1.27 0.95 0.74 0.50 0.25 20 30 Plot the dependence of -In([X]/[X]) on time using software specialized for graphs (e.g., Origin, SigmaPlot, not MS Excell!) and perform the linear data fitting. Export the graph in TIFF format and paste it below as an image. Make sure the graph is graphically appealing! b) From this fitting, calculate the kp of polymerization, assuming the living character of polymerization and an initial initiator concentration (an thus the constant concentration of growing centers) of 0.09 M c) What is the theoretical degree of polymerization (DP) of the prepared polymer? We assume full monomer conversion, complete initiation, absence of…
2. The anionic polymerization of styrene was performed using a 1.38 mol/L solution of styrene in cyclohexane at 40 °C. The polymerization was initiated by 100x10-5 mol/L of butyl lithium and a kinetic order dependence on initiator of 0.5 was observed with an apparent rate constant of 2.4x10-2 observed. The polymerization was run from t = 0 to t= 8000 and a data point collected every t = 200 intervals. Plot [M] vs. time for this reaction.
(e) Pure liquid styrene (phenylethene) is polymerized by adding a soluble peroxide initiator. When the initial monomer concentration is 2.07 M and the peroxide concentration is 2 x 104 M, the initial rate of polymerization (vp) is 2.49 x 103 M min . The rate constant for the decomposition of the initiator (k; ) is 5.7 x 103 min!. (i) Determine the ratio kp/ (kt). State any assumptions. (ii) Calculate the expected number average molecular weight assuming termination takes place by mutual termination only.
1. (a) Write the complete mechanism, including initiation and propagation steps, for the free-radical polymerization of the following reactants: CEN hv ROOR + 2 ?? (b) Include one termination step (not from the initiation step or some species striking a wall).
An elementary reaction is generally expressed as: dC :-kC," dt where A is the species being depleted as the reaction progresses, k is the rate constant, and n is the order of reaction, usually referred to as the stoichiometric coefficient of the resulting product. For a polymerization reaction A> 3B, find the initial amount if after 30 seconds, A species is reduced to 5 moles/L within 3 minutes. Take the rate constant as 0.314 L?/(molľ²-min).
Rate constant, k, for intramolecular of A was determined as 10 min' whereas, second order rate constant, k2 in the presence of trimethylamine was 8.4 x 10- 3 M-1 min-1. A (i) Suggest the form of the above catalysis. (ii) Calculate the effective molarity of the reaction. What is the effective molarity tells about the reaction. (ii) Provide a mechanism of the intramolecular above and their steps to give products. (iv) Provide a mechanism of the intermolecular above and their steps to give products.
Write the steps of ‘Modern Adsorption Theory of Heterogenous Catalysis.’
The rate law for the hydrogenation (H) of ethylene (E) to form ethane (A) over a cobalt-molybdenum catalyst [Collection Czech. Chem. Commun.,51, 2760 (1988)] is (a)Suggest a mechanism and rate-limiting step consistent with the above rate law.(b)What was the most difficult part in finding the mechanism?
2. Derive an expression for the time dependence of the degree of polymerization for the stepwise polymerization of a hydroxyacid HO – R- COOH for which the rate law is dA = -k,[A]²[0H] ,where A denotes the carboxylic acid group.
The first step in the heterogeneoushydrogenation of ethylene is adsorption of theethylene molecule on a metal surface. One proposed explanation for the “sticking” of ethylene to a metalsurface is the interaction of the electrons in the C—C π bond with vacant orbitals on the metal surface. (a) If thisnotion is correct, would ethane be expected to adsorb to a metal surface, and, if so, how strongly would ethane bindcompared to ethylene? (b) Based on its Lewis structure,would you expect ammonia to adsorb to a metal surfaceusing a similar explanation as for ethylene?
2. Czarnowski and H.J. Schuhmacher (Chem. Phys. Lett. 17, 235 (1972)) suggested the following mechanism for the thermal decomposition of F2O in the reaction 2 F20(g) → 2 F2(g) + O2(g): 1) F2O+ F2O →F+OF + F2O : ka ko ke kd 2) F+F20 → F2 + OF: 3) OF + OF → 02 + F + F : 4) F+F+ F2O→ F2 + F2O: Use the steady-state approximation to find the rate law of this reaction.
An elementary reaction is generally expressed as: dC, = -kC," dt where A is the species being depleted as the reaction progresses, k is the rate constant, and n is the order of reaction, usually referred to as the stoichiometric coefficient of the resulting product. For a polymerization reaction A> 3B, find the initial amount if after 30 seconds, A species is reduced to 5 moles/L within 3 minutes. Take the rate constant as 0.314 L'/(moP-min).