Chemistry

Problem

35\,^{\circ}\text{C}

four different reactions were studied. The measured rate expressions and the corresponding numerical values of the rate constant are listed in the table below. However, the units of the rate constant were accidentally omitted during transcription.

Reaction	Empirical rate law	$k$ (numerical value)
1	$k_{1}[\text{F}]^{2}$	$6.7\times10^{2}$
2	$k_{2}[\text{G}]^{1/2}$	$4.5\times10^{-3}$
3	$k_{3}[\text{H}][\text{I}]$	$1.8$
4	$k_{4}$	$9.2\times10^{-5}$

(a) For each reaction, derive the correct units for the rate constant when rate is expressed in

\text{mol}\,\text{L}^{-1}\,\text{s}^{-1}

. (b) Re-express the units for

k_{2}

and

k_{4}

in terms of

\text{mol}

\text{L}

, and

\text{h}

rather than seconds. (c) The laboratory database automatically flags any rate constant whose magnitude is outside the range

10^{-8}

10^{8}

when expressed with units of

\text{L}^{n}\,\text{mol}^{-n}\,\text{h}^{-1}

, where

n

is a positive integer. Indicate which, if any, of the four constants would be flagged after converting to the required hour-based units. Justify your answer quantitatively. (a) Determine units for each

k

\text{mol}\,\text{L}^{-1}\,\text{s}^{-1}

rate format. (b) Convert units of

k_{2}

and

k_{4}

to hour-based units. (c) Identify flagged rate constants with justification.

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