Question

Copper(I) ion undergoes a self-redox reaction to form solid copper and copper(II) ion.

a) Write the balanced equation for the reaction in water.

b) In water, the equilibrium constant for this reaction is ≈10⁶. But if the copper(I) is dissolved in DMSO, the equilibrium constant for the reaction is ≈2. Suggest an explanation.

Answer 1

ANSWER

a) the balanced reaction is given as,

2 [Cu(H2O)6]+ -------> Cu(s) + [Cu(H2O)6]2+ In this given reaction aqeous complex of Cu ions are written, we can also write it as, 2 Cu+(aq) --------> Cu(s) + Cu2+(aq).

b) in water medium the equillibrium constant is 106, this means that the concentration of products are very greater than the reactant Cu+ . This is due to the fact that stability of water complex of Cu2+ ion is more stable than water complex of Cu+.

  The stability of the complex depends on the ligand attached to the metal ion. As water ligand stabilising Cu2+ ion, here in DMSO ligand in DMSO solvent stabilizes more to the Cu+ ion. hence the equillibrium constant for this reaction in DMSO solvent is only 2.