Question

What is the oxidation state of Cobalt in \([Co(NH_3)_6]Cl_3\)?

• A. \(+1\)
• B. \(+2\)
• C. \(+3\)
• D. \(+4\)

Hint:

Neutral ligands such as \(NH_3\), \(H_2O\), and \(CO\) contribute zero charge. Only charged ligands affect the oxidation state calculation.

Answer 1

The Correct Option is C

Concept: In coordination compounds, the oxidation state of the central metal ion can be determined using the charges of ligands and the overall charge of the complex. Important points:
• \(NH_3\) is a neutral ligand.
• \(Cl^{-}\) carries a charge of \(-1\).
• The compound \([Co(NH_3)_6]Cl_3\) contains three chloride ions outside the coordination sphere.

Step 1: Determine the charge on the complex ion. Since there are \(3\) chloride ions \((Cl^-)\), the complex ion must have a charge of: \[ [Co(NH_3)_6]^{3+} \]

Step 2: Let the oxidation state of cobalt be \(x\). \[ x + 6(0) = +3 \]

Step 3: Solve the equation. \[ x = +3 \] Thus, the oxidation state of cobalt is: \[ \boxed{+3} \]