Inert Gases

[305572238]

Dr. Lavelle explicitly stated in lecture that inert gases have no effect on equilibrium when they are added to a system. However, in a UA workshop, the UA said that inert gases shift equilibrium when they are added to a *closed* system. Can someone - maybe Professor Lavelle or a TA - weigh in on how we should approach inert gases when applying Le Chatelier's principle to changes in a reaction if it comes up on an exam?

[Chem_Mod]

See my detailed class discussion on this, including a detailed example.

Also see textbook section 5J.2:

"Compression of a reaction mixture at equilibrium tends to drive the reaction in the direction that reduces the number of gas-phase molecules; increasing the pressure by introducing an inert gas has no effect on the equilibrium composition."

I will discuss with UAs. There must be a miscommunication.

[Warren Jolicoeur 1B]

An inert gas will not react with any part of the reaction, therefore it cannot affect equilibrium.

[Bela Patel 2B]

Inert gases can not react with chemical reactions so it has no affect on the equilibrium, however, as said above it does have an affect on the pressure of the reaction.

[Chem_Mod]

The only change is the pressure increases when an inert gas is added to a fixed volume reaction at equilibrium.

Nothing else changes:

No change in [R].
No change in [P].
Reaction stays in equilibrium (no effect on the equilibrium composition).
No change in K.

To all students asking about adding an inert gas: Please watch my class discussion on this.