The reaction of hydrogen and bromine, H2(g) + Br2(g) → 2 HBr(g). occurs through a radical mechanism. The individual steps may be written asBr2 → Br + Br kaBr+H2 → H+HBr kbH + Br2 → Br+ HBr kcH + HBr → H2 + Br kdBr + Br + M → Br2 + M ka(a) Deduce the expressions for the steady-state concentrations [Br] and [H] from the expressions for the net rates of formation of H and Br. (b) By combining these expressions, show that the rate of formation of HBr is 2kb(ka/ko)' 1/2 [H2] [Br2] 3/2/{[Br2] + (kd/ko)}. (c) What are the orders of the reaction (with respect to each species) when the concentration of H Bris (i) very low, (ii) very high? Suggest an interpretation in each case.

The reaction of hydrogen and bromine, H2(g) + Br2(g) → 2 HBr(g). occurs through a radical mechanism. The individual steps may be written asBr2 → Br + Br kaBr+H2 → H+HBr kbH + Br2 → Br+ HBr kcH + HBr → H2 + Br kdBr + Br + M → Br2 + M ka(a) Deduce the expressions for the steady-state concentrations [Br] and [H] from the expressions for the net rates of formation of H and Br. (b) By combining these expressions, show that the rate of formation of HBr is 2kb(ka/ko)' 1/2 [H2] [Br2] 3/2/{[Br2] + (kd/ko)}. (c) What are the orders of the reaction (with respect to each species) when the concentration of H Bris (i) very low, (ii) very high? Suggest an interpretation in each case.

Physical Chemistry

2nd Edition

ISBN:9781133958437

Author:Ball, David W. (david Warren), BAER, Tomas

Publisher:Ball, David W. (david Warren), BAER, Tomas

Chapter20: Kinetics

Section: Chapter Questions

Problem 20.67E

See similar textbooks

Similar questions

Some reactions proceed through a chain mechanism involving radicals, which are highly reactive species with one or more unpaired electrons. The radicals are produced in initiation steps, through either thermal or photodissociation. Reactions in which the radical centre is transferred are called propagation steps. The radicals are lost in termination steps. Consider the following chain mechanism:(1) AH → A + H·(2) A → B· + C(3) AH + B· → A + D(4) A + B· → P(a) Identify the initiation, propagation, and termination steps.(b) Use the steady-state approximation to deduce that the decompositionof AH is f irst-order in AH.
In the dimerization of methyl radicals at 25 °C, the experimentally determined frequency factor is 2.4 × 1010 dm3 mol−1 s−1. What are (a) the reactive cross-section, and (b) the steric factor for the reaction given that the C–H bond length is 154 pm?
Consider the following mechanism: 1) Br2(g) = 2Br(g) Kc1 = 2.2 x 10^-3 2) Br(g) + H2(g) = HBr(g) + H(g) Kc2 = 7.5 x 10^6 3) H(g) + Br(g) = HBr(g) Kc3 = 350 calculate Kc for the overall reaction
The chemical rxn : N2 + O2 ⟶⟶ NO can be described by the following mechanism. step-1) N2 + 2O2 ⟶⟶ 2NO2 ΔΔH1 step-2) NO + 1212 O2 ⟶⟶ NO2 ΔΔH2 Identify which expression is most consistent with the enthalpy of formation of NO.
The first step in plant photosynthesis is absorption of light by chlorophyll molecules bound to proteins known as ‘light-harvesting complexes’, where the fluorescence of a chlorophyll molecule is quenched by other nearby chlorophyll molecules. Given that for a pair of chlorophyll a molecules R0 = 5.6 nm, by what distance should two chlorophyll a molecules be separated to shorten the fluorescence lifetime from 1 ns (a typical value for monomeric chlorophyll a in organic solvents) to 10 ps?
ASAP Predict the product/products of the reaction. Justify your answer and show the mechanism
Substitution of hydrogen by deuterium is a convenient way to label organic molecules at specific sites for the purpose of investigating reaction mechanisms. At what frequency would the C-D stretch of a phenyl ring appear if the frequency of the C-H stretch is 3062 cm-1?
The rate law v=(kr1[A][B])/(kr2 + kr3[B]1/2) was established in a series of experiments. Identify the conditions under which (i) an order with respect to A, (ii) an order with respect to B, and (iii) an overall order, can be assigned.
Derive the rate law (d[N2O5]/dt) using Steady-State Approximations N2O5 = NO2 + NO3 (K1) NO2 + NO3 = N2O5 (K-1) NO2 + NO3 = NO2 + O2 + NO (K2) NO + N2O5 = 3NO2 (K3)
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 d[A]/dt = −kr[A]2[OH], where A denotes the carboxylic acid group.
At 500 K, what is the fraction of molecular collisions with enough energy to result in a bimolecular reaction with Ea = 80 kJ mol−1?
Distinguish between kinetic and the rmodynamic control of a reaction. Suggest criteria for expecting one rather than the other.