Textbook Question
Choose the molecule in each pair you'd expect to have the higher boiling point. Explain your reasoning.
(b)
2. Molecular Representations
Intermolecular Forces
2:54 minutesProblem 66
Textbook Question
Draw a picture of the hydrogen bonding in methanol.
Verified step by step guidance1
Understand the concept of hydrogen bonding: Hydrogen bonding occurs when a hydrogen atom covalently bonded to an electronegative atom (like oxygen or nitrogen) interacts with another electronegative atom. In methanol (CH₃OH), the oxygen atom is highly electronegative and can form hydrogen bonds with other molecules.
Identify the functional groups in methanol: Methanol consists of a hydroxyl group (-OH) attached to a methyl group (CH₃). The oxygen in the hydroxyl group has lone pairs of electrons, making it capable of forming hydrogen bonds.
Visualize the hydrogen bond donor and acceptor: The hydrogen atom in the hydroxyl group of methanol acts as the hydrogen bond donor, while the oxygen atom with its lone pairs acts as the hydrogen bond acceptor.
Draw the interaction between two methanol molecules: Represent one methanol molecule with its hydroxyl group (-OH) and show the hydrogen atom forming a hydrogen bond with the oxygen atom of another methanol molecule. Use dashed lines to indicate the hydrogen bond.
Ensure proper orientation: In the drawing, make sure the hydrogen bond is depicted between the hydrogen atom of one molecule and the lone pair of electrons on the oxygen atom of the other molecule. Label the partial charges (δ⁺ on hydrogen and δ⁻ on oxygen) to emphasize the polarity of the bond.
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Video duration:
2mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hydrogen Bonding
Hydrogen bonding is a type of attractive interaction that occurs between a hydrogen atom covalently bonded to a highly electronegative atom (like oxygen or nitrogen) and another electronegative atom. In methanol (CH3OH), the hydrogen atom attached to the oxygen can form hydrogen bonds with the oxygen atoms of neighboring methanol molecules, leading to unique physical properties such as higher boiling points.
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Molecular Structure of Methanol
Methanol is a simple alcohol with the chemical formula CH3OH. Its structure consists of a hydroxyl group (-OH) attached to a methyl group (CH3). The presence of the hydroxyl group is crucial for hydrogen bonding, as it provides a site for the hydrogen atom to interact with other electronegative atoms in nearby molecules.
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Intermolecular Forces
Intermolecular forces are the forces of attraction or repulsion between neighboring particles (atoms, molecules, or ions). In the case of methanol, hydrogen bonds are a significant type of intermolecular force that affects its physical properties, such as solubility and boiling point. Understanding these forces is essential for predicting how methanol behaves in different environments.
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