What is Le Chatelier's Principle?

A reaction at equilibrium makes products and reactants at the same speed, so the amounts stay steady. Change something and one direction runs faster until the two speeds match again. The reaction does not return to its old amounts — it settles at a new balance.

Equilibrium does not mean stopped: both directions keep running at matched speeds, so the amounts hold still. Add reactant and collisions increase, the forward direction speeds up, and product builds until the reverse direction catches up and the speeds tie again. At that new balance there is more product than before and also more reactant, because only part of what you added was consumed. Removing product as it forms works the opposite way and pulls the reaction forward continuously, which is why ammonia plants drain product off as it appears. Squeezing a gas mixture shifts it toward the side with fewer gas molecules, since fewer molecules occupy less volume. Heat can be written into the equation as a participant: heating a reaction that releases heat shifts it back toward reactants, and cooling shifts it toward products. A catalyst changes none of this, speeding both directions equally so the same new balance arrives sooner.

A concert lets out, hundreds of people want rides within three blocks, and prices surge — which pays drivers to leave their corners and come over. More drivers arrive and prices ease, but they never drop back to the normal fare, because the crowd is still standing there. The area settles at a new steady price with more drivers working it.