🤓 Based on our data, we think this question is relevant for Professor Richert's class at ASU.

We’re being asked to determine the **time it would take for 25% of the molecules to desorb (leave the surface)**.

The integrated rate law for a first order reaction is as follows:

$\overline{){\mathbf{ln}}{\mathbf{}}{\left[\mathbf{A}\right]}_{\mathbf{t}\mathbf{}\mathbf{=}\mathbf{}}{\mathbf{-}}{\mathbf{kt}}{\mathbf{}}{\mathbf{+}}{\mathbf{}}{\mathbf{ln}}{\mathbf{}}{\left[\mathbf{A}\right]}_{{\mathbf{o}}}}$

where:

**[A] _{t}** = concentration at time t,

**[A] _{0}** = initial

**k** = rate constant,

**t** = time

Since no concentration is given, we can use the given percentages in place of concentration.

The desorption (leaving of the surface) of a single molecular layer of n-butane from a single crystal of aluminum oxide was found to be first order with a rate constant of 0.128/s at 150 K.

If the surface is initially completely covered with n-butane at 150 K, how long will it take for 25% of the molecules to desorb (leave the surface)?

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Based on our data, we think this problem is relevant for Professor Richert's class at ASU.