Indicate the type of solute–solvent interaction (Section 11.2) that should be most important in each of the following solutions: (b) methanol (CH₃OH) in water

Verified step by step guidance

1. Step 1: Identify the type of solute and solvent. In this case, the solute is methanol (CH3OH) and the solvent is water (H2O). Both of these are polar molecules.
2. Step 2: Understand the types of solute-solvent interactions. There are three main types: ion-dipole, dipole-dipole, and London dispersion forces.
3. Step 3: Determine the type of interaction. Methanol and water are both polar molecules, meaning they have a positive and a negative end. Therefore, the most important type of solute-solvent interaction in this solution would be dipole-dipole interaction.
4. Step 4: Understand why dipole-dipole interaction is the most important. This is because both water and methanol are polar molecules, and the positive end of one molecule will be attracted to the negative end of another molecule. This attraction between polar molecules is what makes them dissolve in each other.
5. Step 5: Remember that while dipole-dipole interaction is the most important in this case, other types of interactions like hydrogen bonding (a special type of dipole-dipole interaction) and London dispersion forces can also occur to a lesser extent.

Key Concepts

Solute-Solvent Interactions

Solute-solvent interactions refer to the various forces that occur between solute particles and solvent molecules when a solution is formed. These interactions can include hydrogen bonding, dipole-dipole interactions, and London dispersion forces. The strength and type of these interactions significantly influence the solubility of a solute in a solvent.

Hydrogen Bonding

Hydrogen bonding is a specific type of strong dipole-dipole interaction that occurs when a hydrogen atom covalently bonded to a highly electronegative atom, such as oxygen or nitrogen, interacts with another electronegative atom. In the case of methanol in water, both methanol and water can form hydrogen bonds, which enhances the solubility of methanol in water due to the favorable interactions between the molecules.

Polarity of Molecules

Polarity refers to the distribution of electrical charge over the atoms in a molecule. Polar molecules, like water and methanol, have regions of partial positive and negative charge due to differences in electronegativity. This polarity is crucial in determining solubility, as polar solutes tend to dissolve well in polar solvents, leading to strong solute-solvent interactions.