Question

Could you please explain why the answer is "C"？

Select the type of interaction which best describes the attraction between Mg²⁺ ions and water molecules.

A) dipole-dipole

B) dipole-induced dipole

C) ion-dipole

D) ion-induced dipole

E) ion-hydrogen bond

Answer 1

The attraction between Mg²⁺ ions and water molecules is ion-dipole.

Explanation:

An ion-dipole interaction results when an electrostatic interaction occurs between a charged ion and a molecule that has a dipole. It is an attractive force that is commonly found in solutions, especially ionic compounds dissolved in polar liquids. A cation can attract the partially negative end of a neutral polar molecule, while an anion attracts the positive end of a polar molecule. Ion-dipole attractions become stronger as the charge on the ion increases or as the magnitude of the dipole of the polar molecule increases.

Here, Mg²⁺ is a cation with positive charge and H₂O is a polar molecule with a dipole, where cation Mg²⁺ attract the partially negative end of a water, a neutal polar molecule. So the interaction is ion-dipole.