Substitution reactions

Question 1

What is a ligand substitution reaction?

Answer 1

When one ligand is swapped for another ligand

• if ligands are similar size and have similar charge, then co-ordination number isn’t affected

Question 2

Ligand substitution reactions can be easily reversed unless….

Answer 2

The new complex ion is much more stable than the old one.

e.g. multidentate ligands are stronger than monodentate ligands.

Question 3

Why is the enthalpy change for a ligand substitution reaction considered very small?

Answer 3

This is because the strength of bonds being broken is often similar to the strength of bonds being formed.

Question 4

What happens when monodentate ligands are substituted with multidentate ligands?

Answer 4

Number of particles in the solution increases
- the more particles, the greater the entropy

• reactions that result in an increase in entropy, are more likely to occur

Question 5

why is it difficult to reverse reactions?

Answer 5

Might cause a decrease in entropy

• which may decrease the chance of a reaction occurring

if “triangle G” is negative, then reaction is feasible.