Chapter 12, Problem 12.1P

Interpretation Introduction

Interpretation:

The compounds soluble in hexane are to be identified.

Concept introduction: The polarity of solute and solvent determines the solubility of solution. Solute and solvent of same polarity are soluble with each other and insoluble if polarity is different.

To determine: The compounds soluble in hexane.

Answer to Problem 12.1P

Solution:

1. Water is not soluble in hexane.
2. Propane is soluble in hexane.
3. Ammonia is not soluble in hexane.
4. Hydrogen chloride is not soluble in hexane.

(a)

Explanation of Solution

The molecular structure of water consists of two hydrogen atoms bonded with one oxygen atom. The oxygen atom being electronegative element withdraw electrons from hydrogen atoms and become partial negatively charged.

However, hexane is a non-polar molecule and it does not solubilize polar compounds. Therefore, Water is not soluble in hexane.

(b)

Propane consists of three carbon atoms attached to each other in chain. The dipole moment of same elements bonded with each other is zero. Hence propane is a non-polar molecule and can solubilize in non-polar hexane.

(c)

The three hydrogen atoms in ammonia are bonded with nitrogen atom having one pair of electrons. The structure of the molecule is not symmetrical and nitrogen withdraws electrons towards itself.

Hence, ammonia is a polar molecule. Therefore, it is not soluble in hexane.

(d)

The electronegativity of chlorine in $\text{HCl}$ is very high as it is bonded with electropositive element, Hydrogen. The bond between hydrogen and chlorine is polar.

However, hexane is a non-polar molecule and it does not solubilize polar compounds. Therefore, hydrogen chloride is not soluble in hexane.