The answer to this question will depend on the specific equilibrium reaction in question. In general, if O2 is a reactant in the forward reaction, then removing O2 will shift the equilibrium towards the reactants side, according to Le Chatelier's principle. Conversely, if O2 is a product in the forward reaction, then removing O2 will shift the equilibrium towards the products side.
For example, consider the reaction:
2NO (g) + O2 (g) ⇌ 2NO2 (g)
In this reaction, O2 is a reactant on the forward side. If O2 is removed, the equilibrium will shift towards the reactants side, meaning that the concentrations of NO and O2 will increase, while the concentration of NO2 will decrease.
Which way will equilibrium shift if O2 is removed?
1 answer