Based on the results of Part III, predict the solubility of the following mixtures and explain your answers: a) Methanol (CH3OH) in water. b) Hexane (C6H14) and cyclohexane. c) Hexane and water.
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a) Methanol (CH3OH) in water: Methanol is highly soluble in water. This is because both methanol and water are polar molecules. In methanol, the OH (hydroxyl group) can form hydrogen bonds with water molecules, which is a strong intermolecular force that promotes solubility in water.
b) Hexane (C6H14) and cyclohexane: Hexane and cyclohexane are both nonpolar molecules and share similar intermolecular forces, which are primarily van der Waals interactions (dispersion forces). Since they have similar molecular structures and are both hydrocarbons without polar groups, they are mutually soluble in each other.
c) Hexane and water: Hexane and water are not very soluble in each other. Hexane is a nonpolar molecule, while water is a polar molecule with strong hydrogen bonding. Due to the significant difference in polarity and the types of intermolecular forces between them (hexane has van der Waals forces while water has hydrogen bonding), hexane does not dissolve well in water. The rule of thumb "like dissolves like" suggests that polar and nonpolar substances do not mix well, leading to poor solubility of hexane in water.