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Increasing the pressure by adding an inert gas at constant volume has no effect because only the partial pressures of the reactants and products are important. Adding an inert gas at constant volume will change the total pressure but not the partial pressures of the other gases in the container. The number of moles per unit volume remains the same so the equilibrium does not change
gabbymaraziti wrote:Do you have to change the volume in order to change the pressure? Or would adding a non-inert gas affect pressure as well?
There are many ways to change the pressure. If you change the volume, the partial pressures can change.
If you add a non-inert gas, then the partial pressures can change depending on how the reactive gas reacts with the gases already in the system
In order to change the equilibrium constant you must change the partial pressure of either the products or reactants, such as adding more of the reactants. Adding an inert gas would not change the partial pressure of the reactants or products.
I believe adding an inert gas does not alter the pressure in a rxn system, because the inert gas is not really reactive and does not participate in the reaction that is happening. But, what would happen if you added a reactant that did participate in the reaction, such as a non-inert gas?
Adding an inert gas to the container at constant volume would mean that pressure would increase but the equilibrium would not shift because it is not directly affecting the concentration of reactants and products. If it was the other case where addition of a gas changed the volume at constant pressure, the molar concentrations would decrease and it would shift to the side with lower molar concentration.