Post-Laboratory Questions (use the spaces provided for the answers and additiona
ID: 493371 • Letter: P
Question
Post-Laboratory Questions (use the spaces provided for the answers and additional paper if necessary.) 1. A student doing the experiment in this module extended the study of the ion equilibrium. In one test tube, the student added silver nitrate (AgNO) to a blue equilibrium mixture prepared from CoC12. The reaction mixture became pink and cloudy, and a white precipitate settled out leaving a clear e as silver AgCI Briefly explain how these observations are consistent with Le Chatelier's principle. In a second test, the student placed a test tube containing a pink equilibrium mixture in a hot-wa bath. The solution turned blue. When the student removed the test tube from the hot-water bath a placed it in an ice-water bath, the solution turned pink (2) Is the forward reaction in the ICoCl.l ion/ICo(Hzoohl ion equilibrium exothermic endothermic? (3) Briefly explain how the student's observations support your answer to (2).Explanation / Answer
(1)
If we add acid to the equilibrium mixture of Mg(OH)2, then magnesium hydroxide reacts with the acid,(say,HX) to form a salt , MgX2 and water.
Mg(OH)2 + HX = MgX2 +2H2O
During the reaction if we add indicator then we can the color due to the change of pH.
(2)
The reaction involved for the following:
Mg(OH)2 (s) + 2 CH3CO2H (aq) = Mg(CH3CO2)2 (aq) +2H2O (l)
Here if we use vinegar (CH3CO2H) as the acid.
(3)
As while reaction with the acid very small amount of magnesium hydroxide will left, maximum will dissolve so the amount of magnesium hydroxide available will determine the equilibrium of the reaction.
According to Le Chatelier’s principle the equilibrium will shift to the left, very small amount of magnesium hydroxide will be present in solution. As the acid will reacts the hydroxide ions,more magnesium hydroxide will dissolve.
So, the equilibrium of this reaction can be explained by Le Chatelier’s Principle.