In a solution of 0.150 M CH3CH2CH2NH2, what species is in the highest concentration?

1. Break Down the Problem

To determine which species is in the highest concentration in a 0.150 M solution of CH₃CH₂CH₂NH₂ (propylamine), we need to identify its dissociation behavior in water.

2. Relevant Concepts

Propylamine is a weak base and can accept protons (H⁺) from water, forming its conjugate acid (propylammonium ion, CH₃CH₂CH₂NH₃⁺) and hydroxide ions (OH⁻). The reaction can be represented as follows:

$\text{CH}_{3}\text{CH}_{2}\text{CH}_{2}\text{NH}_{2} + \text{H}_2\text{O} \rightleftharpoons \text{CH}_{3}\text{CH}_{2}\text{CH}_{2}\text{NH}_3^+ + \text{OH}^-$

3. Analysis and Detail

In the solution, propylamine (CH₃CH₂CH₂NH₂) will exist primarily in its unprotonated form, along with some proportion of protonated form (CH₃CH₂CH₂NH₃⁺) and hydroxide ions (OH⁻). However, since propylamine is a weak base, it only partially ionizes in solution.

Given that the initial concentration of propylamine is 0.150 M and that it only partially converts to its conjugate acid, the concentration of unprotonated propylamine remains the highest, as most of it remains in the original form due to the weak base nature.

4. Verify and Summarize

Considering the initial concentration and the weak base dissociation, propylamine (CH₃CH₂CH₂NH₂) will be predominant in solution. Therefore, the concentration of unprotonated propylamine will remain close to its initial concentration.

Final Answer

The species in the highest concentration in a 0.150 M solution of CH₃CH₂CH₂NH₂ is propylamine (CH₃CH₂CH₂NH₂) itself.