Transition Metals

• Cobalt and ammonia is a basic swap with the water ligands because NH3 and H2O are a similar size.

  
• Copper and excess ammonia have incomplete substitution.

  
• Cl- ligand is much larger so changes the coordination number.

  
• The chelate effect is that a positive entropy change is favourable for a more stable complex so it is preferred to have more moles on the right than the left. This is done by swapping unidentate ligands with multi or bidentate ligands.
• A heterogenous catalyst is in a different phase or state to the reactants. The gases can absorb onto the solid catalyst surfaces and bind to the active sites which weakens the bonds. Powder is preferred as it has a large surface area so more active sites. However, catalysts can be poisoned (like sulfur poisoning) in which the active sites are blocked.
• Transition metal ions can allow two negatively charged molecules to react by becoming oxidised (which is possible due to their variable oxidation states) by one of the negative molecules and then react with the other one to reform the original oxidation state.