1. What was the effect of adding excess chloride ions.Use Le Chatlier’s principle and provide evidence.
The effect of adding excess chloride ions would move the equilibrium toward that side which removes the additional Cl-. Also, it would move the equilibrium left toward reaction, until the equilibrium is reestablished.

2. Based upon the heating and cooling of the two equilibrium mixtures, propose if the reaction is endothermic or exothermic. Use Le Chatlier’s principle and provide evidence (would heat be considered as a reactant or product?).
[CoCl4]2-(aq) + 6H2O(l) [Co(H¬2O)6] 2+(aq) + 4Cl-(aq)

For this reaction, the temperature increases which mean that, the heat is added. Therefore, the color changed from pink to light purple. As for the equilibrium concept, its shift to left according to Le Chatlier’s principle. In addition, for this reaction, if the reaction reversed, it would be absorbs heat and if its forward, it would be release heat. Therefore, the heat is a product and the reaction is exothermic.
3. How did the addition of silver nitrate affect the equilibrium if neither silver ions nor nitrate ions are in the equilibrium expression? Use Le Chatlier’s principle and provide evidence. Additionally, write a net ionic equation to describe the precipitation reaction.
The effect of the addition of silver nitrate to the equilibrium reaction is the equilibrium shifts to the right according the Le Chatlier’s principle. As for the concentration of the Cl-, it would be decreased due to precipitated of the silver nitrate. The precipitation reaction equation would be: Ag+(aq) + Cl-(aq) —->AgCl(s).

4. When perturbing the equilibrium with heating and cooling, how many times do you think the equilibrium can be shifted before it stops working? Why? How about modification of the equilibrium through changes in concentration?
The reaction is exothermic. Therefore, the addition of heat will favor backward reaction and the equilibrium would shift left. As for the time, the equilibrium never stops working, as the system would be in continuous equilibrium. In, addition, Modification of equilibrium by addition of reactants, will shift the equilibrium towards right (products) and addition of products would shift the equilibrium towards left (reactants).
[CoCl4]2- (aq) + 6 H2O (l) ——-> [Co(H2O)6]2+ (aq) + 4 Cl- (aq) + Heat