Final answer:
Le Chatelier's Principle is demonstrated with a simple experiment using cobalt(II) chloride in water, observing color changes that result from shifts in equilibrium due to added water or hydrochloric acid.
Step-by-step explanation:
Le Chatelier's Principle explains how a chemical system at equilibrium responds to various stresses, such as changes in concentration, temperature, and pressure. A simple experiment to illustrate Le Chatelier's principle is to observe the effect of changing concentration on the equilibrium involving cobalt(II) chloride. In this system, cobalt(II) chloride in water exists as a dynamic equilibrium between the pink Co(H2O)6^2+ ions and the blue CoCl4^2- ions. Adding water to the mixture increases the concentration of water, causing the equilibrium to shift and make the solution pink, as more Co(H2O)6^2+ ions are formed. Conversely, adding concentrated hydrochloric acid (HCl) increases the chloride ion concentration, shifting the equilibrium to form more CoCl4^2- ions, and turning the solution more blue.
This visual change clearly shows the principle at work as the system adapts to counteract the added stress of changing ion concentrations. Thus, by simply adding water or hydrochloric acid, one can visibly manipulate the equilibrium position and demonstrate Le Chatelier's principle in a classroom or home setting.