Based on the type or types of intermolecular forces, predict the substance in each pair that has the higher boiling point: (a) propane (C₃H₈) or n-butane (C₄H₁₀) (b) diethyl ether (CH₃CH₂OCH₂CH₃) or 1-butanol (CH₃CH₂CH₂CH₂OH) (c) sulfur dioxide (SO₂) or sulfur trioxide (SO₃) (d) phosgene (Cl₂CO) or formaldehyde (H₂CO)

Verified step by step guidance

1. Identify the types of intermolecular forces present in each molecule. Phosgene (Cl₂CO) and formaldehyde (H₂CO) both exhibit dipole-dipole interactions due to their polar nature.
2. Consider the possibility of hydrogen bonding in each molecule. Formaldehyde (H₂CO) has hydrogen atoms bonded to oxygen, which can participate in hydrogen bonding.
3. Assess the molecular weights and size of the molecules. Phosgene (Cl₂CO) is heavier and larger compared to formaldehyde (H₂CO), which can influence the strength of the dipole-dipole interactions.
4. Compare the overall strength of the intermolecular forces in each molecule. The presence of hydrogen bonding in formaldehyde (H₂CO) generally leads to stronger intermolecular forces compared to just dipole-dipole interactions in phosgene (Cl₂CO).
5. Predict the substance with the higher boiling point based on the stronger intermolecular forces. In this case, formaldehyde (H₂CO) is likely to have a higher boiling point due to the presence of hydrogen bonding.

Key Concepts

Intermolecular Forces

Intermolecular forces are the attractive forces between molecules that influence physical properties such as boiling and melting points. The main types include hydrogen bonding, dipole-dipole interactions, and London dispersion forces. Understanding these forces helps predict how substances behave under different conditions, particularly in terms of phase changes.

Boiling Point

The boiling point of a substance is the temperature at which its vapor pressure equals the external pressure, allowing it to transition from liquid to gas. Substances with stronger intermolecular forces typically have higher boiling points because more energy is required to overcome these attractions. Thus, comparing boiling points can provide insights into the nature of the intermolecular forces present.

Polarity and Molecular Structure

Polarity refers to the distribution of electrical charge over the atoms in a molecule, which affects its intermolecular interactions. Molecules like formaldehyde (H2CO) are polar due to the presence of a carbonyl group, leading to dipole-dipole interactions. In contrast, phosgene (Cl2CO) has a more complex structure that can influence its overall polarity and the types of intermolecular forces it exhibits.