Consider the insoluble compound copper(II) carbonate , CuCO 3 . The copper(II) i
ID: 507171 • Letter: C
Question
Consider the insoluble compound copper(II) carbonate , CuCO3. The copper(II)ion also forms a complex with ammonia . Write a balanced net ionic equation to show why the solubility of CuCO3(s) increases in the presence of ammonia and calculate the equilibrium constant for this reaction.
For Cu(NH3)42+, Kf = 6.8×1012. Use the pull-down boxes to specify states such as (aq) or (s).
FIND K ALSO
Consider the insoluble compound iron(II) sulfide , FeS . The iron(II) ion also forms a complex with cyanide ions . Write a balanced net ionic equation to show why the solubility of FeS (s) increases in the presence of cyanide ions and calculate the equilibrium constant for this reaction.
For Fe(CN)64-, Kf = 7.7×1036. Use the pull-down boxes to specify states such as (aq) or (s).
FIND K --------
Explanation / Answer
a) CuCO3(s) <---> Cu2+ (aq ) + CO32-(aq). Ksp = 1.4×10^-10
Cu2+(aq) + 4NH3(aq) <----> [Cu(NH3)4]2+(aq) Kf = 6.8×10^12
Adding these two equation
CuCO3(s) + Cu2+(aq) + 4NH3(aq) <----> Cu+(aq) + CO32-(aq) + [Cu(NH3)4]2+(aq)
Net ionic eequation is
CuCO3(s) + 4NH3 (aq)<-------> [ Cu(NH3)4]2+(aq) + CO32-(aq)
K = Ksp × Kf
= 1.4×10^-10 × 6.8×10^12
= 9.52 × 10^2
b) FeS(s) <----> Fe2+(aq) + S2-(aq) Ksp = 6 × 10^-19
Fe2+(aq) + 6CN- (aq)< ------> [Fe(CN)6]4-(aq) Kf=7.7×10^36
Adding these equation
FeS(s) + Fe2+(aq) + 6CN-(aq)<------> Fe2+(aq) + S2-(aq) + [Fe(CN)6]4-(aq)
net ionic equation is
FeS(aq) + 6CN-(aq) <------> [Fe(CN)6]4-(aq) + S2-(aq)
K = Ksp × Kf
= 6×10^-19 × 7.7×10^36
= 4.6 × 10^17