Question

1. For the following compound:

2K3[Cr(C2O4)3] . 3H2O

Potassium trioxalatochromate(III) trihydrate

Identifythe following terms and give examples of each:  (2 points each).

Lewis Acid.

Lewis Base.

Ligand.  

Coordination Compound.

Coordination Sphere.

Coordinate or dative covalent bond.

Coordination number (number of atoms bonded directly to the metal).

Oxidation number (of the Lewis Acid)

Counter ions.

Answer 1

2K3[Cr(C2O4)3] . 3H2O

a) Lewis acid: chromium (III) ion is the Lewis acid which is accepting electrons from the oxygen of C2O4 (2-) ions.

b) lewis base : C2O4 (2-) ions. because they are donating electrons to metal center.

c) ligand : C2O4 (2-) oxalate ions are the ligand which binds to metal center in given coordination number.

d) coordination compound: they are the result of the reaction of ligands( Lewis base) and metal center ( lewis acid )

K3[Cr(C2O4)3] is the coordination compound.

e) coordination sphere : the compound given inside the [ ] bracket is the coordination sphere. [Cr(C2O4)3]

f) coordinate bond: the bond between lewis base ( oxygen of oxalate here) and lewis acid ( chromium metal)

g) coordination number : the number of bonds formed by the metal in coordination sphere. it is 6 for 2K3[Cr(C2O4)3] . 3H2O

h) oxidation number of chromium is +3

i) counter ions are the ions present outside coordination sphere. here it is potassium(K) ions.