Chemical Kinetics HW1 (Kahn, 2010)

Home , Addition reaction, Electrophilic addition

Question 1. (6 pts) A reaction with stoichiometry A = P + 2Q was studied by monitoring the concentration of the reactant A as a function of time for eighteen minutes. The concentration determination method had a maximum error of 6 M. The following concentration profile was observed:

Time (min) Conc (mM)

1 0.9850 2 0.8571 3 0.7482 4 0.6549 5 0.5885 6 0.5183 7 0.4667 8 0.4281 9 0.3864 10 0.3557 11 0.3259 12 0.3037 13 0.2706 14 0.2486 15 0.2355 16 0.2188 17 0.2111 18 0.1930

Determine the reaction order and calculate the rate constant for decomposition of A. What can be said about the mechanism or molecularity of this reaction?

Question 2. (4 pts) Solve problem 2 on pg 31 in your textbook (House) using both linear and non-linear regression. Provide standard errors for the rate constant and half-life based on linear and non-linear fits. Below is the data set for your convenience: dataA = {{0, 0.5}, {10, 0.443}, {20,0.395}, {30,0.348}, {40,0.310}, {50,0.274}, {60,0.24}, {70,0.212}, {80,0.190}, {90,0.171}, {100,0.164}}

Question 3. (3 pts) Solve problem 3 on pg 32 in your textbook (House).

Question 4. (7 pts)

The authors of the paper “Microsecond Folding of the Cold Shock Protein Measured by a Pressure-Jump Technique” suggest that the activated state of folding of CspB follows Hammond- type behavior. Write a concise, 1-page essay that addresses the following points: 1) What does one mean when they say that a chemical process follows Hammond-type behavior? 2) What kind of kinetic data would an organic chemist collect in order to establish that an electrophilic addition reaction follows Hammond-type behavior? 3) What is the evidence of Jacob et al to support their claim that folding of this cold shock protein follows Hammond-type behavior?

You may want to consult your Organic Chemistry (Bruice) textbook, an original paper by George Hammond from 1953, his 1985 commentary on this citation classic, and two papers by Alan Fersht and coworkers on Hammond-type behavior in protein folding (1993 and 1995). These papers are available at the course website.