The gas-phase reaction has the experimentally determined rate law (the reaction is…

CHEMISTRY · Multi-part · A Level · Chemistry · Rate equations · Rate equations

Problem

The gas-phase reaction

J(g) + K(g) + L(g) \rightarrow \text{products}

has the experimentally determined rate law

rate = k[J]^2[K]

(the reaction is zero order in L). At

500\,\text{K}

, the following initial data are collected:

[J]_0 = 0.080\,\text{M}

[K]_0 = 0.060\,\text{M}

[L]_0 = 0.040\,\text{M}

Initial rate

r_0 = 1.15 \times 10^{-3}\,\text{M s}^{-1}

The system temperature is then lowered to

480\,\text{K}

, but it is specified that the rate constant

k

remains unchanged over this small temperature interval. New concentrations are prepared as follows:

[J] = 0.050\,\text{M}

[K] = 0.120\,\text{M}

[L] = 0.010\,\text{M}

Answer the questions below, showing all calculation steps and including correct units throughout. (a) Determine the numerical value and units of the rate constant

k

using the initial data. (b) Calculate the reaction rate under the new set of concentrations at

480\,\text{K}

. (c) By what factor has the rate changed relative to

r_0

? Express your answer both as a multiple of

r_0

and as a percentage change. (d) Provide a brief explanation for why the change in

[L]

does not influence the rate, making explicit reference to the reaction order with respect to

L

Related theory

Browse the problem library