the reaction has to take place in a closed system i.e. a rigid closed chemical reactions are reversible BUT the reaction has to take place in a closed system i.e. a rigid closed container with stable external conditions… temperature, pressure, nothing let in or out!

Closed systems reach a state of equilibrium when the RATE of the forward rxn equals the RATE of the reverse rxn NOTE: It is NOT necessary to have equal amounts of reactants and products

Equilibrium is dynamic When equilibrium is reached the forward and the reverse reactions keep going BUT it looks as if the reaction has stopped, because the opposing rates are equal, and the concentrations stay constant!

Chemical Tug of War

3 Types of Equilibrium Systems Chemical reactions (the focus of the rest of this topic) Solution equilibrium in saturated solutions at constant temp, the rate of dissolving is equal to the rate of crystallization (precipitation)

3. Physical changes in phases / states H2O (s) H2O (l) H2O (l) H2O (g)

THE ↔ END