What factors contribute to the increasing boiling points of propanol, propanediol and propanetriol?
1. Molecular weight: As the molecular weight of a compound increases, its boiling point also tends to increase. Propanetriol (glycerol) has the highest molecular weight among the three compounds, followed by propanediol (1,2-propanediol) and propanol (1-propanol).
2. Hydrogen bonding: Propanediol and propanetriol are capable of forming hydrogen bonds due to the presence of hydroxyl functional groups (-OH) in their molecular structure. This results in stronger intermolecular forces between molecules, leading to higher boiling points compared to propanol which can only form weaker dipole-dipole interactions.
3. Number of hydroxyl groups: Propanetriol has three hydroxyl groups per molecule, while propanediol has two and propanol has only one. The presence of multiple hydroxyl groups leads to increased hydrogen bonding, further raising the boiling point of the compound.
4. Polarity: As mentioned before, propanediol and propanetriol are more polar compounds compared to propanol. This increased polarity results in stronger intermolecular forces, contributing to higher boiling points.
5. Size and shape of molecules: The larger and more complex molecular structures of propanediol and propanetriol compared to propanol can also play a role in their higher boiling points. Larger molecules often have more surface area for intermolecular interactions, leading to increased boiling points.