Question

When dioxygen is adsorbed on a metallic surface, the electron transfer occurs from the metal to the molecule. The true statements regarding this adsorption are:

• A. $O_2$ is physisorbed
• B. Heat is released
• C. Occupancy of ${\pi }_{2px}^{\ast }$ $O_2$ is increased
• D. Bond length of $O_2$ is increased

Answer 1

Answer: (B), (C), (D)

Bond length of $O_2$ is increased

One of the first things we need to understand here is that process taking place here is chemisorption. We know that chemisorption is an exothermic process which means heat is released. It happens through electron donation which goes on to occupy the $\pi$ ABMO of $O_2$. Since oxygen now forms a $M-O$ bond, the $O-O$ bond length increases.