Phenolphthalein is a weak acid and is colorless in solution although its ion is pink. If half of the liquid is poured out and the bottle is sealed carbon dioxide will leave the liquid phase at an ever-decreasing rate and the partial pressure of carbon dioxide in the gas phase will increase until equilibrium is reached. Chemical Equilibrium Le Chatelier S Principle Teaching Chemistry Chemistry Classroom Equilibrium When a conductor acquires an excess charge the excess charge moves about and distributes itself about the conductor in such a manner as to reduce the total amount of repulsive forces within the conductor. . Equilibrium states are reached for physical as well as chemical reactions. At equilibrium these systems tend to contain significant amounts of both products and reactants indicating that there is not a strong tendency to form either products from reactants or reactants from products. These balanced chemical reactions form the ...