Question

2. The ε and σ values for Lennard-Jones potential of xenon are found to be 1.77 kJ/mol and 4.10 Å, respectively. The ε and σ values for Lennard-Jones potential of argon are found to be 0.997 kJ/mol and 3.40 A, respectively. Plot the L-J potentials for Xe-Xe and Ar-Ar interactions, which potential has a deeper minimum (i.e. stronger interatomic interactions)? Why?

Answer 1

as shown in the plotted L-J potentials for Xe-Xe and Ar-Ar ,

Xe-Xe potential has deeper minimum because this is V vs r graph and its derivative ( dv/dr i.e. slope ) if concave down/ negative slope -attractive if concave up/positive slope -repulsive in nature

in this Xe-Xe have deeper minimum than Ar-Ar because

Xe-Xe have more vander waals radius and

repulsion exponent for xenon (12) is higher than Ar(9) as shown below-

Ar -9

Xe- 12