(d) The first-order rate constants for the fluorescence and phosphorescence of molecule X are 4.5 x 107 s' and 0.50 s', respectively. Briefly explain the large order of magnitude difference in the rate constant values. (c) Explain how long (in s) it takes for 1.0% of fluorescence and phosphorescence to occur following termination of excitation.

(d) The first-order rate constants for the fluorescence and phosphorescence of molecule X are 4.5 x 107 s' and 0.50 s', respectively. Briefly explain the large order of magnitude difference in the rate constant values. (c) Explain how long (in s) it takes for 1.0% of fluorescence and phosphorescence to occur following termination of excitation.

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter30: Kinetic Methods Of Analysis

Section: Chapter Questions

Problem 30.14QAP

See similar textbooks

Similar questions

The fluorescence of a fluorophore is quenched in the presence of iodide ions. (i) Would the fluorescence quantum yield in the presence of iodide be larger or smaller than the fluorescence quantum yield in the absence of iodide? Explain your answer. (ii) Would the fluorescence lifetime of the fluorophore in the presence of iodide be longer or shorter than the lifetime in the absence of iodide? Explain your answer.
Calculate the magnitude of the diffusion-controlled rate constant at 320 K for the recombination of two atoms in water, for which η = 0.89 cP. Assuming the concentration of the reacting species is 1.5 mmol dm−3 initially, how long does it take for the concentration of the atoms to fall to half that value? Assume the reaction is elementary.
Calculate the magnitude of the diffusion-controlled rate constant at 320 K for the recombination of two atoms in benzene, for which η = 0.601 cP. Assuming the concentration of the reacting species is 2.0 mmol dm−3 initially, how long does it take for the concentration of the atoms to fall to half that value? Assume the reaction is elementary.
Suggest a plausible mechanism for this reaction that is consistent with the rate law.
Discuss the featu res. applications. and limitations of the Michaelis-Menten mechanism of enzyme action .
Calculate the orders of the reaction with respect to I–, BrO3 , and H+ –using the aforementioned systematic approach. In order to simplify this task, the proper experiments are provided. The orders should be rounded to the nearest integer.
a. Express the rate in terms of change of concentration of A with respect to time where 2A + B -> products, rate = k[A]-1. b. Give the derived integrated rate law. c. What is the derived expression for half-life with respect to A in terms of k and [A]o?
It has been found that in acid solution (greater than 1M H3O+) the rate expression rate for the reaction of H2O2 with I- is of the form : rate= k2[H2O2][I-][H3O+], where k2 = .25L2*mol-2*s-1 at 25C. Therefore, the rate law over the whole range of acidity from very acid solutions to a neatural solution is given be a two-term rate expression: rate = k1[H2O2][I-] + K2[H2O][I-][H3O+] Where K1 has the value of .0115L*mol-1*s-1 at 25C. Compare the relative magnitudes of these two terms under the conditions employed in your rate measurements for mixture 1. ( you should find what that the second term makes a negligible contribution to the reaction rate at H3O+ smaller than 3 x 10 -4) mixture 1 concentrations H2O2 = 5.3 x10-5 I- = 8.3 x 10 -6 H3O = 10-5
The decomposition of [A] in solution at 75C proceeds via first order: A (aq) yields B (aq) What is the rate law for the reaction?
Binding of hormone to two different receptors.Examination of the binding of a particular hormone to two different receptors yields the data in the following table. What is the reverse (dissociation) rate coefficient, kD, for the release of the hormone from the receptor?
The ha lf-l ife of pyruvic acid in the presence of an aminotransferaseenzyme (which converts it to alanine) was found to be 221 s. How long will it take for the concentration of pyruvic acid to fal l to 1/ 64 of its in it ial va lue in th is first-order reaction?
Suppose that, in the absence of a catalyst, a certain biochemicalreaction occurs x times per second at normal bodytemperature (37 °C). In order to be physiologically useful,the reaction needs to occur 5000 times faster than when itis uncatalyzed. By how many kJ>mol must an enzyme lowerthe activation energy of the reaction to make it useful?