Oxidation Number

To determine the oxidation number of cobalt (Co) in the complex [Co(H₂NCH₂CHNH₂)₃]₂(SO₄)₃, we follow these steps:

• The complex formula [Co(H₂NCH₂CHNH₂)₃]₂(SO₄)₃ includes:
  • Cobalt [Co]
  • Tris(ethylenediamine) ligands [H₂NCH₂CHNH₂]
  • Sulfate ions (SO₄)
• Ethylenediamine (en) is a neutral ligand, so it does not affect the overall charge of the complex.
• Sulfate ion (SO₄) has a charge of -2. Since there are three sulfate ions, their total contribution to the charge is 3 × (-2) = -6.
• The complex as a whole is neutral, so the sum of charges within [Co(en)₃]₂ must be +6 to balance the -6 from the sulfates.
• Let x be the oxidation state of one cobalt ion. Therefore, the equation considering 2 Co centers is:
  
• Solve for x:
  
  
• Thus, the oxidation number of Co in the complex is .