Why does the equation Co(H2O)6 + 4Cl <------> CoCl4 + 6H2O shift left when cooled?
[Co(H2O)6]^2+ + 4Cl^- + heat ==> (CoCl4)^2-^
Le Chatelier's Principle tells us that a system in equilibrium will shift so as to undo what we do to it. If we add heat the reaction above will shift to the right in order to use up the heat we've added. If we cool the system it will shift to the left in order to add heat back to the system.
The equation you provided represents a complex ion, specifically the formation of hexaaquocobalt(II) ions and tetrachlorocobaltate(II) ions. The equation can be written as:
Co(H2O)6 + 4Cl^- ⇌ CoCl4^- + 6H2O
When this equilibrium is cooled, it shifts to the left. This can be explained by Le Chatelier's principle, which states that when a system at equilibrium is subjected to a change, the equilibrium will shift in the direction that counteracts the change.
In this case, cooling the system decreases the temperature. Since the forward reaction is an exothermic reaction (releases heat), it can be thought of as having heat as a product. Therefore, by decreasing the temperature, you are essentially removing one of the products. According to Le Chatelier's principle, the equilibrium will shift in the direction that forms more heat, which is the reverse reaction.
As a result, the reaction shifts to the left to produce more Co(H2O)6 and 4Cl^- ions, and decrease the concentration of CoCl4^- and 6H2O ions. This shift helps to offset the decrease in temperature and maintain equilibrium.
The shift of the equation Co(H2O)6 + 4Cl <------> CoCl4 + 6H2O to the left when cooled is due to the principle of Le Chatelier's Principle. According to Le Chatelier's Principle, when a system in equilibrium is subjected to a change in temperature, pressure, or concentration, it will try to counteract the change and establish a new equilibrium.
In this case, cooling the system represents a change in temperature. When the system is cooled, it decreases the temperature, which can be considered a shift to the left since heat is on the left side of the reaction. The reaction Co(H2O)6 + 4Cl <------> CoCl4 + 6H2O is an example of a complex ion formation reaction.
To understand why the reaction shifts to the left when cooled, we need to consider the heat as a reactant in the forward reaction. Cooling the system means removing heat, which decreases the concentration of heat in the mixture. According to Le Chatelier's Principle, when the concentration of a reactant is reduced, the equilibrium will shift in the direction that produces more of that reactant. In this case, since heat is considered a reactant, the reaction will shift to the left to produce more heat.
In summary, when the equation Co(H2O)6 + 4Cl <------> CoCl4 + 6H2O is cooled, it shifts to the left because cooling reduces the concentration of heat in the system, and according to Le Chatelier's Principle, the equilibrium will shift in the direction that produces more of the reactant, in this case, heat.