Question

The oxidation states of Cr in [Cr(H₂O₆]Cl₃, [Cr(C₆H₆)₂] and K₂[Cr(CN)₂(O)₂(O₂) (NH₃)] respectively are ______.

Options

• +3, +4 and +6

• +3, +2 and +4

• +3, 0 and +6

• +3, 0 and +4

Answer 1

The oxidation states of Cr in [Cr(H₂O₆]Cl₃, [Cr(C₆H₆)₂] and K₂[Cr(CN)₂(O)₂(O₂) (NH₃)] respectively are +3, 0 and +6.

Explanation:

Hydrogen peroxide (H₂O₂) acts as a reducing agent in an alkaline (basic) medium, converting Fe³⁺ to Fe²⁺. The reaction is:

\[\ce{Fe^{3+} + H2O2 + OH- -> Fe^{2+} + O2 + H2O}\]

Sodium peroxide (Na₂O₂) reacts with water to produce hydrogen peroxide and sodium hydroxide, creating the necessary alkaline condition for the reduction to occur:

\[\ce{Na2O2 + 2H2O -> 2NaOH + H2O2}\]