Question

1.	The second-order rate constant for self-reaction of hydroxyl radicals 2 OH → H2O + O has the value 1.0786E9 M-1·s-1 at 360.0 K. Compute the half-life of OH radicals at this temperature if the initial concentration is 6.74E-6 M.

3.	Calculate the initial rate of a first-order reaction if the concentration of reactant is 0.37 M and the half-life is 4.48 s. Enter the correct numerical value to 2.0% precision. Express scientific notation like 4.29E-15 M·s-1
	4.	Cyano radicals abstract H atoms from methane at 349.0 K according to the second-order reaction CN + CH4 → HCN + CH3 Under conditions where [CH4] = 0.487 M is present in great excess (i.e. pseudo-first-order conditions), the concentration of [CN] was observed to decrease from 2.604E-6 M to 8.5079E-8 M in 11.5 ns. Calculate the second-order rate constant for the reaction under these conditions. M-1·s-1
	5.	Consider the hypothetical reaction A → products Determine the order of the reaction given the initial reaction rates below. [A] Initial rate 1.77E-2 M 2.059E5 M-1·s-1 6.62E-2 M 3.982E5 M-1·s-1
	6.	Consider the generalized second-order reaction R → products If the initial concentration is [R]0 = 3.307E-6 M and the half-life is 930.0 microseconds, compute the rate constant for the reaction. M-1·s-1
	7.	A sample of ancient linen cloth weighing 21.0 mg produces 0.132813 14C disintegration counts per second (cps), compared with 13.88 cps obtained from a 1.000 g calibration standard of contemporary organic material. From this measurement, determine the apparent age of the linen sample.
	8.	Hydroperoxy radicals undergo the second-order self-reaction 2 HO2 → H2O2 + O2 The rate constant for this reaction is 7.5621E8 M-1·s-1 at 856.0 K. If the initial concentration of HO2 is 1.67E-6 M, compute the time required for the concentration to be reduced to 0.500E-6 M s
	9.	Gaseous cyano radicals react with oxygen according to CN + O2 → OCN + O The rate constant for this reaction at 885.0 K is 8.3456E9 M-1·s-1. If [O2] = 0.15 M and is present in great excess (i.e., pseudo-first-order conditions where [O2]>>[CN]) what is the predicted half-life of cyano radicals under these conditions? s

Answer 1