Quick questions on Solubility, aqueous solutions and like dissolves like: VCE Chemistry Unit 1

A solution is a homogeneous mixture. The solvent is the component in larger amount (often the liquid); the solute is what is dissolved. For most of Unit 1, the solvent is water and we are asking whether the solute will dissolve in it.

A non-polar solvent (hexane, toluene, cyclohexane) interacts with its solutes only by dispersion. Adding a non-polar solute swaps dispersion for dispersion and dissolves; adding a polar or ionic solute would require breaking strong solute-solute forces and replacing them with much weaker dispersion, so they do not dissolve. This is why oil-and-water emulsions separate but oil and petrol mix.

Explain why iodine ($\text{I}_2$) is more soluble in hexane than in water. [2 marks]

A solution is prepared by dissolving $11.7 \, \text{g}$ of $\text{NaCl}$ in $250 \, \text{mL}$ of water. Calculate (a) the molar concentration and (b) the concentration of $\text{Na}^+$ ions in $\text{mol/L}$. [3 marks]

Compare the solubility behaviour of glucose, sodium chloride and naphthalene in water. (a) Identify the dominant solute-solvent interaction in each case. (b) Rank the three by approximate solubility in water.