The rate of a surface catalyzed reaction between CO(g) and O2(g) follows Langmuir-Hinshelwood mechanism. If O2 gets dissociated during adsorption, the rate of the reaction is [where, p represents the partial pressure and K represents the surface binding constant on the species. k is a proportionality constant]
Reactions on surfaces are reactions in which at least one of the steps of the reaction mechanism is the adsorption of one or more reactants. The mechanisms for these reactions, and the rate equations are of extreme importance for heterogeneous catalysis.
Langmuir–Hinshelwood mechanism
In this mechanism, two molecules adsorb on neighboring sites and the adsorbed molecules undergo a bimolecular reaction:
Substance ‘A’ is exposed to 600nm, 100 W light source for 6626s, with 50% of the incident light being absorbed. ‘A’ decomposes according to the reaction A→B . As a result of irradiation, 0.2 mol of B is produced. The quantum yield of the reaction is closest to
The concentration (C) of a compound undergoing decomposition as a function of time (t) is given below:
The order of the reaction is
For a reaction, raising the temperature from 200K to 300K results in the increase of rate constant by a factor of 2. The activation energy for this reaction in kJ mol-1 is closest to (ln2=0.69).
For the reaction,
the equilibrium constant is 0.16 and k1 is 3.3×10-4s-1.The experiment is started with pure cis from. The time taken for half the equilibrium amount of trans isomer to be formed is about
The rate constant for the reaction, A2B4O→AB4 +AO is described as, . The activation energy for this reaction (in kJ mol-1) is closest to
The rate of decomposition of a gas is The order of the reaction is:
The effective activation energy for the reaction:
with the following potential energy versus reaction coordinate plot is
A protein has 3 tyrosine residues and ‘n’ tryptophan residues both of which are the only amino acids absorbing at 280nm. If the absorbance of the protein having a concentration of
in a cuvette of path length 2 cm) is 0.59, the number of tryptophan residues in the protein must be
The effective rate constants for a gaseous unimolecular reaction:
following the Lindemann-Hinshelwood mechanism are
respectively. The rate constant for the activation step in the mechanism is approximately equal to (in
The predicted rate law, using the steady state approximation, for the reaction
