write equalibrium reaction Activity Formation of Copper Complex lon An equilibri
ID: 912845 • Letter: W
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write equalibrium reaction Activity Formation of Copper Complex lon An equilibrium system can be formed in a solution of copper (I) ions and ammonia. A copper ammonia complex ion forms when the amount of in solution reaches a high enough concentration. Plea note that 3 is provided in the form of a concentrated for convenience as Cu NH3. Initial Conditions Add approximately 5 mL of 0.2 M CuSO4 to a test tube. In a fume hood, add the concentrated ammonium hydroxide solution dropwise Procedure Observations Initial color of copper Explanation solution Add concentrated NH3 olution dropwise. 13 Flinn ScientificExplanation / Answer
Procedure--------------------------------------Observation----------------------------------Explanation_-----------------------------------------------
Initial color of copper-------------------------Blue solution--------------------------------It is due to ionization of a soluble aqueos solution ---------------------------------------------------------------------------------------------salt solution yielding Cu 2+ ion. The blue ----------------------------------------------------------------------------------------------------------color is the charecteristic color of -------------------------------------------------------------------------------------------------------------------- Cu 2+ ion.
Add concentrated NH3 ----------------1 ) A bluish white precipitate ------------- It is due to fomation of copper (II) solution dropwise -----------------------------appears first -------------------------------hydroxide , Cu (OH)2 according to -------------------------------------------------------------------------------------------------------------------following reaction---------------------------------------------------------------------------------------------------------------------------------------------Cu^ 2+ + 2OH^ - ---------------->Cu(OH) 2 ------------------------------------------------------------------------------------------------------Note that the OH^- is givenout by ionization ----------------------------------------------------------------------------------------------------------of aqueous solution of ammonia ( ie. ---------------------------------------------------------------------------------------------------------------NH4OH ) as - ------------------------------------------------------------------------------------------------------------------------------------------------NH4 OH (aq)<--------------> NH4 ^+ (aq) + --------------------------------------------------------------------------------------------------------OH^- (aq) -------------------------------------------------2) The bluish white precipitate----------- The bluish white precipitate dissolves in ------------------------------------------------------dissolves in excess of ammonia------ excess of ammonia due to formation of --------------------------------------------------------to yield an intense blue solution ------ cupraamine -complex Cu ( NH3 )4 2+ -------------------------------------------------------------------------------------------------------------ion which has a charecteristic deep blue-------------------------------------------------------------------------------------------------------------color.
-----------------------------------------------------------------------------------------------------------The reaction is: -----------------------------------------------------------------------------------------------------------------------------------------------Cu2+ (aq ) + 4NH3 (aq) <------------------> -----------------------------------------------------------------------------------------------------------[ Cu ( NH3 )4 ]2+ (aq)---------------------------------------------------------------------------------------------------------------------------------------[ deep blue ]
Add 1.0 M HCl dropwise--------- 3) The deep blue color fades ---------------- it is due to decomposition of the ----------------------------------------------------------------------------------------------------------------------cupraamine complex forming CuCl2 ------------------------------------------------------------------------------------------------------------------Reaction --------------------------------------------------------------------------------------------------------------------------------------------------------- [Cu ( NH3 )4 ]2+ + 2 Cl- <------------> ------------------------------------------------------------------------------------------------------------- Cu Cl2 ----------------------------------------------Add additional drops of NH3 -------The deep blue color reappears--------------It is due to formation of cupraamine ------------------------------------------------------------------------------------------------------------------complex when ammonia is in excess ( ie. ----------------------------------------------------------------------------------------------------------in ammoniacal medium ) , according to --------------------------------------------------------------------------------------------------------------the reaction given above.
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