Question

Suppose that NaCl is added to hexane (C6H14) instead of water. Which of the following intermolecular forces will exist in the system?
Check all that apply.

Ion-dipole force between Na+ ions and a hexane molecule
Ion-ion force between Na+ and Cl− ions
Dipole-dipole force between two hexane molecules
Hydrogen bonding between Na+ ions and a hexane molecule
London dispersion force between two hexane molecules

Answer 1

Answer:

Ion-ion force between Na+ and Cl− ions

London dispersion force between two hexane molecules

Explanation:

"Ion-dipole force between Na+ ions and a hexane molecule " does not exist since hexane has only non-polar bonds and therefore no dipole.

"Ion-ion force between Na+ and Cl− ions " exists since both are ions.

"Dipole-dipole force between two hexane molecules " does not exist since hexane molecules do not have a dipole.

"Hydrogen bonding between Na+ ions and a hexane molecule " does not exist since the hydrogen in the hydrogen bond must be bonded directly to an electronegative atom, which hexane does not have since it is a hydrocarbon.

"London dispersion force between two hexane molecules" exist since hexane is a molecular compound.

Answer 2

Answer:

Ion-ion force between Na⁺ and Cl⁻ ions.

London dispersion force between two hexane molecules.

Explanation:

Suppose that NaCl is added to hexane (C₆H₁₄) instead of water. Which of the following intermolecular forces will exist in the system?

Check all that apply.

• Ion-dipole force between Na⁺ ions and a hexane molecule. NO. Hexane is nonpolar so it can interact through ion-dipole forces.

• Ion-ion force between Na⁺ and Cl⁻ ions. YES. Na⁺ is a cation (positive ion) and interacts with the anion (negative ion) Cl⁻ through ion-ion forces.

• Dipole-dipole force between two hexane molecules. NO. Since hexane molecules are not dipoles, they do not show dipole-dipole interaction.

• Hydrogen bonding between Na⁺ ions and a hexane molecule. NO. Hydrogen bonding requires H bonded to a very electronegative atom, such as N, O or F, which does not happen in hexane.

• London dispersion force between two hexane molecules. YES. The kind of interaction between nonpolar molecules is London dispersion force.