What is the oxidation number of Fe in K4 Fe (CN)6

CONCEPT:

Oxidation Number

• The oxidation number (or oxidation state) of an atom in a molecule or ion is the hypothetical charge that atom would have if all bonds to atoms of different elements were 100% ionic.
• Rules for assigning oxidation numbers:
  • Oxidation number of a free element is 0.
  • Oxidation number of a monoatomic ion is equal to its charge.
  • Group 1 elements in compounds have an oxidation number of +1, and Group 2 elements have +2.
  • In compounds, hydrogen is assigned +1, and oxygen is assigned -2 (except in peroxides and superoxides).
  • The sum of the oxidation numbers in a neutral compound is 0, and in a polyatomic ion, it equals the charge of the ion.

EXPLANATION:

• In the given compound K₄[Fe(CN)₆]:
  • The compound is electrically neutral, so the sum of oxidation numbers of all atoms is 0.
  • Potassium (K) is in Group 1, so its oxidation number is +1. Since there are 4 potassium atoms, the total contribution from potassium is 4 × (+1) = +4.
  • The cyanide ion (CN^-) has a charge of -1. Since there are 6 cyanide ions, the total contribution from cyanide is 6 × (-1) = -6.
• Let the oxidation number of Fe be x. 

  4 × (+1) + x + 6 × (-1) = 0

  +4 + x - 6 = 0

  x = +2

Therefore, the oxidation number of Fe in K₄[Fe(CN)₆] is +2.