Chapter 3, Problem 59P

Interpretation Introduction

Interpretation:

The lower molecular weight of alcohol more soluble in water than higher molecular weight alcohol, has to be explained.

Concept introduction:

Solubility: The general rule that in solubility is like dissolve like, in other words, polar compounds dissolve in polar solvents, and non-polar compounds dissolve in non-polar solvents.

Polarity: The polar solvent such as a water has partial charges that can interact with the partial charges on a polar compound.  The negative poles of the solvent molecule surround the positive pole of the polar compound and the positive pole of polar compound.  The clustering of the solvent molecules around the polar molecules separates them from each other, which is make them dissolve.

Non-polarity: The non-polar compounds have no charge, polar solvents are not attached to them.  For a non-polar molecule to dissolve in polar solvent, the non-polar molecule would have to push the water molecules apart, disrupting their hydrogen bonding.

Dipole interaction: The boiling points of all organic molecules like (ether, alkyl halide, amines, alcohols) also increase molecular weight because in the London dispersion forces.  The boiling points of these compounds, however are also affected the polar ($\text{C-Z}$) bonds here ($\text{Z= N, O, F, Cl}$).  Generally alcohols have higher boiling point when compare to other organic molecules, because addition of London dispersion forces and the dipole-dipole interaction of the polar C-O bond, alcohol can from hydrogen bonds.