4. Substitution reactions

Question 1

what is ligand substitution?

Answer 1

when one ligand is swapped for another ligand

Question 2

1. during a substitution the coordination number and the shape doesn’t change if the ligands are
2. e.g. [Cr(H2O)6]3+(aq) + 6NH3 (aq)

Answer 2

1. similar sized e.g. H2O, NH3, CN-

2. [Cr(NH3)6]3+(aq) + 6H2O

Question 3

what does ligand substitution usually cause

Answer 3

a colour change

Question 4

1. during a substitution the coordination number and the shape change if the ligands are
2. [Cu(H2O)6]2+(aq) + 4Cl-(aq)

Answer 4

1/different sizes e.g.H2O, Cl-

2.[CuCl4]2-(aq) + 6H2O(l)

Question 5

1. sometime substitutions can be only _____

2. e.g. [Cu(H2O)6]2+(aq) + 4NH3(aq)

Answer 5

1. partial

2. [Cu(NH3)4(H2O)2]2+ + 4H2O(l)

Question 6

Why is haemoglobin able to form 6 coordinate bonds?

Answer 6

Haemoglobin contains Fe2+ ions

which form 6 coordinate bonds

Question 7

Structure of haemoglobin

Where do the lone pairs come from?

Answer 7

4 lone pairs come from nitrogen atom on a circular part of a molecule called haem
1 lone pair comes from nitrogen atom on a protein (globin)
1 lone pair comes from H2O ligand

Question 8

how does Fe2+ in Haemoglobin allow Oxygen to be carried in the blood?

Answer 8

1. in lungs O2 concentration high. Water ligand substituted for O2 molecule = Oxyhaemoglobin
2. Oxyhaemoglobin carried around the body.
3. When arrived at a place where O2 is needed O2 molecule is exchanged for H2O molecule.

Question 9

How does carbon monoxide (CO) prevent Haemoglobin from transporting O2

Answer 9

1. when CO inhaled Haemoglobin swaps H2O ligand for CO ligand = carboxyhaemoglobin
2. CO is a strong ligand, doesn’t readily exchange with O2 or H2O ligands = haemoglobin can’t transport O2 anymore.