Question

Use the information and data given below to answer the questions (a) to (c): Stronger intermolecular forces result in higher boiling point. Strength of London forces increases with the number of electrons in the molecule. Boiling point of HF, HCl, HBr and HI are 293 K, 189 K, 206 K and 238 K respectively. (a) Which type of intermolecular forces are present in the molecules HF, HCl, HBr and HI ? (b) Looking at the trend boiling points of HCl, HBr and HI, explain out of dipole-dipole interaction and London interaction, which one is predominant here. (c) Why is boiling point of hydrogen fluoride highest while that of hydrogen chloride lowest?

Answer 1

a) “Dipole interaction” and “London forces” are present in the molecules “HCl”, “HBr”, and “HI”.

b) The dipole moment of “HCl > HBr > HI”, but the boiling point of “HCl < HBr < HI”. This means that “London forces” prevail over the “dipole-dipole interaction”, depending on the surface area. HCl has the lowest surface area, while HI has the highest surface area.

c) HF has the highest dipole moment due to the highest electro-negativity difference, so hydrogen bonding is also present, which increases the attractive force and therefore has a higher boiling point.

Answer 2

hlo mate....
here is the answer....

b) HI has heigher surface area
c)HF has highest boiling point