Chapter 19, Problem 6RAT

Suggest why sodium chloride, NaCl, is insoluble in gasoline. Consider the electrical attractions.

(a) Since this molecule is so small, there is not much opportunity for the gasoline to interact with it through any electrical attractions.

(b) Since gasoline is a very polar molecule, the salt can only form dipole—induced dipole bonds, which are very weak, giving it a low solubility in gasoline.

(c) Since gasoline is so strongly attracted to itself, the salt, NaCl, is excluded.

(d) Salt is composed of ions that are too attracted to themselves. Gasoline is nonpolar so salt and gasoline will not interact very well.

To determine

The reason of insolubility of sodium chloride in gasoline by considering the electrical attractions.

Answer to Problem 6RAT

The best answer is option (d) as the salt is composed of ions which are attracted to themselves and gasoline being non-polar to salt, do not interact with it.

Explanation of Solution

Solubility is the ability of a solute to dissolve in a solvent. Solubility of a solute depends on the sub microscopic attractions present among the solute and solvent particles. Also in solubility the principle like dissolves like is applicable i.e. if a solute is polar and ionic then it will be soluble in polar solvent and if a solute is non-polar then it will be soluble in non-polar solvent.

NaCl solute being ionic in nature, its ions ${\text{Na}}^{\text{+}}{\text{and Cl}}^{-}$ are attracted towards each other with electrostatic forces of attraction and gasoline is a non-polar compound having long chain of hydrocarbons. As like dissolves like, NaCl being polar and ionic will not be soluble in non-polar gasoline.

Conclusion:

Therefore the best option is (d).