Steric Contribution

[Katherine Delgadillo 2H]

Can someone explain what steric contribution is and how it affects delta S? The orange book briefly mentions it, so I just want clarification/further explanation. Thanks!

[Chris Huerta 2D]

The steric contribution has to do with the orientation of molecules during a collision. The more specific an orientation must be for molecules to have an interaction with each other, the more unfavorable their steric contribution. In terms of delta S, since the molecules must be more ordered in order for the reaction to occur, the delta S of the reaction would need to be negative since there is less disorder in the system.