Question

Compounds that contain an \(\mathrm{N}-\mathrm{H}\) group associate by hydrogen bonding. (a) Do you expect this association to be stronger or weaker than that of compounds containing an \(\mathrm{O}-\mathrm{H}\) group? (b) Based on your answer to part (a), which would you predict to have the higher boiling point, 1-butanol or 1-butanamine?

Short answer

Question: Compare the hydrogen bonding strength in compounds containing N-H and O-H groups, and predict which compound will have a higher boiling point between 1-butanol and 1-butanamine. Answer: The association between compounds containing O-H groups is stronger than that of compounds containing N-H groups. 1-butanol has a higher boiling point than 1-butanamine due to the stronger hydrogen bonding in compounds containing O-H groups.

Step-by-step solution

Understanding hydrogen bonding

Hydrogen bonding is an intermolecular force that occurs between a hydrogen atom bonded to a highly electronegative atom (such as nitrogen, oxygen or fluorine) and an electronegative atom on a neighboring molecule. Hydrogen bonds are weaker than covalent bonds but stronger than van der Waals forces.

Comparing N-H and O-H hydrogen bonding strength

To determine whether the hydrogen bonding association is stronger in compounds containing N-H or O-H groups, we need to compare the electronegativity values of nitrogen and oxygen. Oxygen is more electronegative than nitrogen (3.44 vs. 3.04 on the Pauling scale). This results in stronger attraction between hydrogen and oxygen atoms, consequently forming stronger hydrogen bonds compared to those formed by N-H groups.

Answer for part (a)

The association between compounds containing O-H groups is stronger than that of compounds containing N-H groups.

Understanding boiling points and intermolecular forces

Boiling points are influenced by the strength of intermolecular forces between molecules. A stronger intermolecular force results in higher boiling points because more energy is required to break these forces and convert the substance from liquid to gaseous state.

Identifying the functional groups in 1-butanol and 1-butanamine

Let's identify the functional groups present in 1-butanol and 1-butanamine to predict their boiling points. 1-butanol (C4H9OH) contains an O-H group, while 1-butanamine (C4H9NH2) contains an N-H group.

Predicting the boiling points based on hydrogen bonding strength

Since O-H hydrogen bonds (found in 1-butanol) are stronger than N-H hydrogen bonds (found in 1-butanamine), we can conclude that 1-butanol will have stronger intermolecular forces. Consequently, the boiling point of 1-butanol will be higher compared to 1-butanamine.

Answer for part (b)

1-butanol has a higher boiling point than 1-butanamine due to the stronger hydrogen bonding in compounds containing O-H groups.