Equilibrium reaction where the number of moles of reactants and products are the same Le Chatelier's principle says that for an equilibrium reaction where all reactants and products are gases a change in pressure will change the number of moles of the product such to counteract the change in pressure.
My textbook also states that this only affects reactions in which the number of reactants and products are different.
I'm trying to think of a gaseous equilibrium reaction where the number of moles of reactants and products are the same.
All suggestions welcome.
A simple example:
If $T &gt; \pu{100 °C},$ and $p \leq \pu{1 atm},$ then water will be in the gas phase and:
$$\ce{CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g)}$$
Note, however, that while this reaction's equilibrium will be highly insensitive to pressure changes (within the regime that all molecules remain in the gas phase), it will not be entirely insensitive to pressure.
That's because, even though there are the same number of moles of gas on the LHS and RHS, these are real gases, and thus their molar volumes will differ slightly. This is a small effect compared to the effect of actually having different numbers of moles of gases on the LHS and RHS.