Why doesn't a catalyst change the equilibrium position?

A catalyst doesn't change the equilibrium position because it speeds up both the forward and reverse reactions equally.

In more detail, a catalyst is a substance that increases the rate of a chemical reaction by lowering the activation energy, which is the energy required to initiate the reaction. However, it's important to understand that a catalyst does not affect the energy of the reactants or the products. It simply provides an alternative reaction pathway with a lower activation energy. This means that while a catalyst can help a reaction reach equilibrium faster, it does not change the position of the equilibrium itself.

The position of equilibrium in a chemical reaction is determined by the relative energies of the reactants and products. If the products have lower energy than the reactants, the reaction will tend to go to completion, and the equilibrium will lie to the right. If the reactants have lower energy than the products, the reaction will tend not to proceed very far, and the equilibrium will lie to the left. A catalyst does not change these relative energies, so it does not change the position of equilibrium.

Moreover, a catalyst affects both the forward and reverse reactions equally. This is because a catalyst simply provides an alternative reaction pathway with a lower activation energy for both directions of the reaction. Therefore, while the catalyst speeds up the rate at which the reaction reaches equilibrium, it does not favour one direction over the other. This means that the position of equilibrium - the ratio of products to reactants at equilibrium - remains unchanged.

In conclusion, while catalysts are incredibly useful for speeding up chemical reactions and helping them reach equilibrium more quickly, they do not have any effect on the position of equilibrium in a reaction. This is a fundamental principle of chemical equilibrium that is crucial for understanding how reactions proceed.