Posted by Kyo on October 30, 2007 at 17:37:20:
In Reply to: (Oct 30) Qns posted by Kyo on October 30, 2007 at 17:36:22:
Ans to Q5.
[Cu(H2O)6]2+ (aq) + 2OH-(aq) --> Cu(OH)2(H2O)4 (s) + 2H2O (l) --- reaction 1
Cu(OH)2(H2O)4 (s) <--> Cu2+ (aq) + 2OH- (aq) + 4H2O (l) --- reaction 2
Cu2+ (aq) + 4NH3 (aq) <--> [Cu(NH3)4]2+ (aq) --- reaction 3
Reaction 1 shows the formation of the blue ppt.
Reaction 2 shows the equilibrium reaction of the blue ppt and it's constituent ions.
When *excess* aqueous ammonia (ie. a reactant in reaction 3) is added, position of equilibrium of reaction 3 shifts to the right (ie. more product oriented, to get rid of excess NH3), causing an increased uptake of Cu2+ (ie. the other reactant in reaction 3), hence causing the position of equilibrium of reaction 2, to also shift to the right (ie. more product oriented, to replace loss of Cu2+).
Consequently, the blue ppt dissolves (in favour of forming the tetraaminecopper(II) ion).
Ans to Q6
0.587 atm
Ans to Q7
+4
Ans to Q8
-22.2 kJ/mol
Ans to Q9
0.0208 dm3
Ans to Q10
+2