Textbook Question
Determine the kinds of intermolecular forces that are present in each element or compound. d. N2
Ch.12 - Liquids, Solids & Intermolecular Forces
Chapter 12, Problem 46b
In each pair of compounds, pick the one with the higher boiling point. Explain your reasoning. b. CH3OH or CH3SH
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Identify the functional groups present in each compound: CH_3OH has a hydroxyl group (-OH), and CH_3SH has a thiol group (-SH).
Consider the type of intermolecular forces present in each compound: CH_3OH can form hydrogen bonds due to the presence of the -OH group, while CH_3SH can only form weaker dipole-dipole interactions and London dispersion forces.
Recall that hydrogen bonding is a stronger intermolecular force compared to dipole-dipole interactions and London dispersion forces, leading to higher boiling points.
Compare the strength of the intermolecular forces: CH_3OH, with hydrogen bonding, will have stronger intermolecular forces than CH_3SH, which lacks hydrogen bonding.
Conclude that CH_3OH will have a higher boiling point than CH_3SH due to the presence of hydrogen bonding.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hydrogen Bonding
Hydrogen bonding is a strong type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like oxygen or nitrogen. In the case of CH3OH (methanol), the presence of an -OH group allows for hydrogen bonding, significantly increasing its boiling point compared to compounds that cannot form such interactions.
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Molecular Polarity
Molecular polarity refers to the distribution of electrical charge over the atoms in a molecule. Polar molecules, like CH3OH, have regions of partial positive and negative charge, which leads to stronger intermolecular forces. In contrast, CH3SH (methanethiol) is less polar, resulting in weaker van der Waals forces and a lower boiling point.
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Intermolecular Forces
Intermolecular forces are the forces of attraction or repulsion between neighboring particles (atoms, molecules, or ions). The strength of these forces directly affects the boiling point of a substance; stronger intermolecular forces, such as hydrogen bonds in CH3OH, lead to higher boiling points compared to weaker forces in CH3SH.
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Related Practice
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