What kind of intermolecular forces act between an ammonia molecule and a hydrogen fluoride molecule?
Note: If there is more than one type of intermolecular force that acts, be sure to list them all, with a comma between the name of each force.
Hydrogen bonding, dipole-dipole interactions or forces, london dispersion forced
The Correct Answer and Explanation is :
The intermolecular forces that act between an ammonia (NH₃) molecule and a hydrogen fluoride (HF) molecule include hydrogen bonding, dipole-dipole interactions, and London dispersion forces.
Explanation:
- Hydrogen Bonding:
Hydrogen bonding occurs when a hydrogen atom that is covalently bonded to a highly electronegative atom (like nitrogen or fluorine) forms an attractive interaction with another electronegative atom that has a lone pair of electrons. In the case of ammonia (NH₃), the nitrogen atom is highly electronegative, and it has a lone pair of electrons. In hydrogen fluoride (HF), the fluorine atom is also highly electronegative and has lone pairs. The hydrogen of the NH₃ molecule forms a hydrogen bond with the fluorine of the HF molecule because of the strong attraction between the hydrogen and the lone pair on the fluorine. This type of interaction is particularly strong because both nitrogen and fluorine are highly electronegative, making the hydrogen atoms significantly positively charged, which attracts the lone pairs of electrons on the fluorine atoms. - Dipole-Dipole Interactions:
Both ammonia and hydrogen fluoride are polar molecules. Ammonia has a permanent dipole because nitrogen is more electronegative than hydrogen, creating a partial negative charge on nitrogen and a partial positive charge on hydrogen. Similarly, HF is also polar because fluorine is more electronegative than hydrogen. Therefore, the positive end of one molecule (the hydrogen of ammonia) is attracted to the negative end of the other molecule (the fluorine of HF), and vice versa, resulting in dipole-dipole interactions. - London Dispersion Forces:
London dispersion forces (also called van der Waals forces) arise due to the temporary fluctuations in electron density, which create temporary dipoles even in non-polar molecules. Though both ammonia and hydrogen fluoride are polar, they still experience London dispersion forces because all molecules exhibit these forces to some extent. These forces are generally weaker than hydrogen bonding or dipole-dipole interactions but still contribute to the overall intermolecular interaction between the two molecules.
In summary, the intermolecular forces between an ammonia and hydrogen fluoride molecule are hydrogen bonding, dipole-dipole interactions, and London dispersion forces.