equilibrium constant (K)

The equilibrium constant (K) is a number that describes the balance between reactants and products in a chemical reaction at equilibrium. It tells us how far the reaction has progressed: whether it favors the formation of products or reactants. If K is large, the reaction produces mostly products; if small, it favors reactants. K is based on the concentrations of substances and remains steady once equilibrium is reached, regardless of how the reaction got there. This helps scientists predict and understand the behavior of chemical systems in various conditions.