Question

12. For each of the four problems below, consider the two pairs of atoms/ions/molecules. Which pair (i or ii) would be attracted to one another by the strongest intermolecular interaction? Justify your answer, making sure to name the type(s) of intermolecular interaction(s) that are involved in each case. You will receive no credit without a proper justification.

a. (5 points) i) Two argon atoms OR ii) two xenon atoms?

b. (5 points) i) Two NH3 molecules OR ii) two PH3 molecules?

c. (5 points) i) A Cl- ion and a K+ ion OR ii) a water molecule and a K+ ion?

d. (5 points) i) A Cl- ion and a K+ ion (dissolved in methanol, dielectric constant 33) OR ii) a Cl- ion and a K+ ion (dissolved in water, dielectric constant 78).

Answer 1

A) argon and xenon are non polar compound. So the force of attractions between them are London dispersion forces

Size of xenon is more than argon, by increasing size dispersion increases. So, two xenon atoms have more attractions than two argon atoms

B) two NH3 molecules forms Hydrogen bonds where as in between two PH3 molecules have only dipole-dipole attractions. Hydrogen bond is stronger than dipole-dipole attractions

So, two NH3 molecules have strong attractions than two PH3

C) Cl- ion and K+ ion have strong electro static force of attractions ( ionic bond) but K+ion and water molecule have ion dipole attractions. Ionic bond is stronger than ion dipole attractions

So, Cl- ion and K+ion have strong attractions

D) dielectric constant is more that solvent have high soluble capacity

Dielectric constant of water is greater than methanol

So, K+ ion and Cl-ions are have strong attractions with water

Thank you ?

All the best.