Question 1 List all types of intermolecular forces used in the condensed phase for hydrogen sulfide

1. Hydrogen bonding, London Dispersion Forces, Dipole-dipole

2. London Dispersion Forces, Dipole-dipole

3. Hydrogen bonding, Dipole-dipole

4. Hydrogen bonding, London Dispersion Forces

5. None of the answer choices are correct.

Hydrogen bonding, Dipole-dipole

Explanation:

Let us look closely at the structure of H2S, this will enable us to decide if it will show dipole-dipole interaction or not. Given that Sulphur has a greater electro negativity compared to Hydrogen, we expect that the S – H bond will be a polar bond with the direction of polarity pointing towards the sulphur atom according to the usual convention in chemistry. Now, we know that H2S is a bent molecule (there are two lone pairs on the central sulphur atom which leads to a bent molecular geometry), therefore, the vectorial sum of the bond dipole moments will produce a non- zero total dipole moment. This implies that there is a permanent non-zero dipole moment in H2S therefore we expect the molecule to exhibit dipole-dipole interactions .

Similarly, we know that hydrogen bonding exists when hydrogen is bonded to a highly electronegative element such as fluorine, sulphur, oxygen etc. In H2S, hydrogen is bonded to sulphur hence we expect that there should be hydrogen bonding between H2S molecules. Hydrogen bonding is actually a type of dipole-dipole interaction.