Arrange these compounds in order of increasing boiling point: a. CH4, b. CH3CH3, c. CH3CH2Cl, d. CH3CH2OH. Explain your reasoning.

Name: Chemistry: A Molecular Approach
Author: Tro
ISBN: 9780134874371

검증된 단계별 안내

Identify the intermolecular forces present in each compound.

Recognize that CH4 and CH3CH3 are nonpolar molecules, so they only have London dispersion forces.

Note that CH3CH2Cl is polar and has dipole-dipole interactions in addition to London dispersion forces.

Observe that CH3CH2OH has hydrogen bonding, which is stronger than dipole-dipole interactions and London dispersion forces.

Arrange the compounds in order of increasing boiling point based on the strength of their intermolecular forces: CH4 < CH3CH3 < CH3CH2Cl < CH3CH2OH.

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Intermolecular Forces

Intermolecular forces are the attractive forces between molecules that influence physical properties like boiling points. The main types include hydrogen bonding, dipole-dipole interactions, and London dispersion forces. Compounds with stronger intermolecular forces generally have higher boiling points due to the increased energy required to separate the molecules.

Hydrogen Bonding

Hydrogen bonding is a specific type of strong dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like oxygen, nitrogen, or fluorine. In the context of the given compounds, CH3CH2OH (ethanol) exhibits hydrogen bonding, significantly raising its boiling point compared to compounds without this interaction.

Molecular Weight and Structure

Molecular weight and structure also play a crucial role in determining boiling points. Generally, larger molecules with greater molecular weights have higher boiling points due to increased London dispersion forces. However, the presence of functional groups and their ability to engage in hydrogen bonding can override this trend, as seen in the comparison of CH3CH2Cl and CH3CH2OH.