Bio1332 Biochemistry - Lecture Eleven - Intermolecular Forces And Solubility

In a Van der Waals interaction, the induced dipoles are small and temporary. This means that they are not permanent and only exist for a short period of time. These induced dipoles occur due to temporary fluctuations in electron distribution within molecules, creating temporary positive and negative charges. These temporary dipoles then induce dipoles in neighboring molecules, resulting in attractive forces between the molecules. However, once the external influence causing the temporary dipoles is removed, the molecules return to their original state with no permanent dipole moment.

Van der Waals interactions are vital in maintaining the structure and stability of cells. These interactions occur between the lipid molecules that make up the lipid bilayer, which is the main component of the cell membrane. The hydrophobic tails of the lipid molecules interact through van der Waals forces, allowing the formation of a stable and flexible membrane. This membrane acts as a barrier, regulating the transport of molecules in and out of the cell, and maintaining the integrity and shape of the cell.

The interaction between molecules with permanent dipoles, such as polar molecules, enables compounds to dissolve. This is because the positive end of one molecule is attracted to the negative end of another molecule, creating an electrostatic attraction. This interaction allows the molecules to mix and disperse evenly throughout a solvent, resulting in the dissolution of the compound.

Compounds that show extensive hydrogen bonding tend to dissolve well in water. This is because water molecules are highly polar and can form hydrogen bonds with other polar molecules. These hydrogen bonds help to stabilize and solvate the compound, allowing it to dissolve in water. Therefore, the statement "Compounds which show extensive hydrogen bonding will not dissolve in water" is false.

Solvation involves two compounds mixing together. This process occurs when a solute is dissolved in a solvent, resulting in the solute particles becoming dispersed and surrounded by the solvent particles. The solute and solvent interact with each other, forming a solution. Solvation is a physical process and does not involve a chemical reaction or binding between the compounds. Therefore, the correct answer is "Mixing."

When two substances mix together, the intermolecular attractions between the molecules play a crucial role in determining whether they will dissolve or not. For complete dissolution to occur, the sum of the intermolecular attractions between the molecules after mixing must be more than or equal to the sum of the intermolecular attractions between the molecules before mixing. This means that the combined attractive forces between the molecules in the mixture should be at least as strong as the attractive forces between the molecules in their separate states.