$6\mathrm{.}8$ V$.$ Y$.,$ Konyukhov, N$.$ V$.$ Kul'kova, and M$.$ I. Temkin $[$Kinet$.$

Catal., $21,496(1980)]$ studied the kinetics of the hydrogena$-$

tion of benzoic acid $($A$)$ to cyclohexylcarboxylic acid $($B$)$ over

palladium on an activated charcoal catalyst.

$C_6{H}_5\frac{C}{O}OH+3H_2{C}_6{H}_{11}\frac{C}{O}OH$

At typical reaction conditions hydrogen gas is passed through

a well$-$stirred solution of benzoic acid in liquid butanol in

which very fine catalyst particles are suspended.

$($a$)$ These authors suggested that the mechanism of this reac$-$

tion is of the following form:

where o represents a vacant surface site and where the

species in parentheses represent adsorbed reaction inter$-$

mediates. Because the last stcp eccurs so rapidly, surface

coverage by species $Z$ is very, very small $($i$.$e$.,{}_Z$~~$0).$

$($b$)$ Figare P$6\mathrm{.}8-1$ is a plot of the total rate of product fot$-$

mation versus mass of suspended catalyst for reaction at

$130C,$ an initial benzoic acid coscentration of $0\mathrm{.}4$M$,$ and

a hydrogen pressure of $50$utm. What are the implications

of this figure?

Figure P$6\mathrm{.}8-2$ is a plot of the reaction rate per unit

mass of catalyst versus the product $C_A{P}_{M_1}.$ The data cor$-$

respond to reaction at $130C$ at a catalyst leading of $0\mathrm{.}5g.$

The data in the figure represent two types of experiments:

the diamonds correspond to data at a fixed acid concen$-$

tration $(0,4M)$ and variable hydrogen pressure.

The triangles in the figure correspond to a constant hydro$-$

gen pressure of $50$ atm.

Is the proposed mechanism consistent with the data?

Determine numerical values for any kinetic parameters

$($or their products or quoticnts$)$ for which this is possible.

Figure P$6\mathrm{.}8-1$ Dependence of reaction rate on the mass of catalyst

present.

dependence of the rate law on the concentration of benzoic acid and

hydrogen presiure.