Question

I am sort of confused on what these are asking? An explination of the concepts would really help, I will give thumbs up :)

3. Consider the following reactions: a) The formation of tetraaqua copper (Il) ion in solution Cu2+ + 4H2O(l) = [Cu(H2O)4](aq) b) The reaction of ammonia with water. NH3(aq) + H2O(l) = NH4+ (aq) + OH(aq) c) The self ionization of water 2H2O(0) — H3O*(aq) + OH(aq) d) The formation of copper (II) hydroxide [Cu(H20)4]2+ (aq) + 2OH(aq) = Cu(OH)2 (s) + 4H2O(0) e) The formation of the tetraammine copper (II)ion. [Cu(H20)]2+ (aq) + 4NH3(aq) = Cu[(NH3)4]2+ (aq) + 4H20 (1) 5. Use the above reactions to explain your observations, include in your discussion the following: a. How the presence of hydroxide ions affects the formation of Cu(OH)2 b. Why did the addition of ammonia cause a precipitate? c. Why did adding excess ammonia cause the precipitate to disappear?

Answer 1

Please comment for any clarification.

When NH₃ is added to the solution, a precipitate is formed which gets dissolved on further adala of NH3 solution. These observations can be explained on the basis of odbave given reactions as follows a la concentration Of hydroxide ions affect the formation of CUCOH)2. According to reaction : [Cu CH₂O) 4 ] 24 Cag) + 2014 (ag) ² Cu(OH)/s) + 4H₂O(l) In this equilibrium, if or in concentration increases, equilibrium will shift in forward direction to undo this change according to Le Chateliers Principle. Thus more cu COH)2 will form of oh amount decreases, equilibrium shifts in backward direction and Cucom), formation decreases NH3(aq) + H2O(l) = Nhy (aq) + oHlag) When ammonia is added in the solution, it dissociates to give ÕH ions. These hydroxide ions react with [Cu CH20)412+ complex to form CucoH), precipitate of I light blue color. Due to the addition of excess ammonia , a shift in equilibrium takes place to the right. TOUCH₂ O) 4 ]2+ (aq) + 4NH3(aq) & (Cu (NH₃)4] - (aq) + 4H₂010 Excess NHz leads to formation of [Cu(NH3)4] complex land [Cu CH₂O) 4] 27 decreases. Iru (H₂O) u 2+ (aq) + 204 (aq? Cu(OH)₂ (s) + 44,00) This decrease in amount of [Cu(H₂O) 4 ) 24 complex causes above equilibrium to shift in left direction. Thus precipitate of Cu(OH)2 starts to disappear.