CHEMISTRY · Multi-part · AP · Chemistry · Compound Structure and Properties · Compound Structure and Properties
Problem
Two potential–energy curves, L and M, correspond to two electronic states of the N₂ molecule.
• Curve L: minimum energy = –945 kJ·mol⁻¹ at 110 pm
• Curve M: minimum energy = –617 kJ·mol⁻¹ at 124 pm
Assume that the vertical and horizontal scales are identical for both curves.
(a) Calculate the ratio of the bond energies (depths) of curves L and M. Express the ratio EL/EM to three significant figures.
(b) Using your result from part (a) and the equilibrium bond lengths provided, determine which curve is more likely to correspond to the ground electronic state of N₂. Explain your reasoning.
(c) Suppose the molecule in the electronic state represented by curve M absorbs a photon and is promoted to the state represented by curve L. Describe qualitatively what will happen to the average internuclear distance immediately after absorption and as the molecule relaxes back toward equilibrium.