Question

The oxidation number of Co in complex \( [Co(H_2NCH_2CH_2NH_2)_3]_2(SO_4)_3 \) is?

• A. +2
• B. +3
• C. +1
• D. +4

Hint:

To determine the oxidation number of an element in a coordination complex, balance the charges of the ligands and counterions. Use the fact that the total charge of the complex must equal zero.

Answer 1

The Correct Option is B

In the complex \( [Co(H_2NCH_2CH_2NH_2)_3]_2(SO_4)_3 \), the \( \text{SO}_4^{2-} \) ions contribute -2 charge each. 
Since there are three \( \text{SO}_4^{2-} \) ions per complex, the total negative charge is \( 3 \times (-2) = -6 \). 
Let the oxidation number of Co be \( x \). 
Since the complex is neutral, the sum of charges must equal zero. 
For each Co complex, we have: \[ 2x + (-6) = 0 \] \[ 2x = 6 \] \[ x = 3 \] Thus, the oxidation number of Co is +3.