Balance the below half-reaction, which takes place in acidic solution. cr2o72 - (aq) → cr3 (aq) how many electrons are transferred in the balanced half-reaction

The equation is as follow,

Cr₂O₇²⁻ → Cr³⁺

Balance the Cr atoms,

Cr₂O₇²⁻ → 2 Cr³⁺

Identify Oxidation Number of Elements on Both sides,

Left Hand Side;

Cr = + 6

O = - 2

Right Hand Side;

Cr = + 3

O = - 2

Means each Cr is gaining 3 electrons to change into + 3 state, Hence, 6 electrons are gained by two Cr atoms, So,

Cr₂O₇²⁻ + 6e⁻ → 2 Cr³⁺

Balance Oxygen atoms, as it is acidic medium, add H⁺ ion on the side containing large number of Oxygen atoms and H₂O on side containing less number of Oxygen atoms, So,

H⁺ + Cr₂O₇²⁻ + 6e⁻ → 2 Cr³⁺ + H₂O

Now Balance H and O,

14 H⁺ + Cr₂O₇²⁻ + 6e⁻ → 2 Cr³⁺ + 7 H₂O

6 electrons are transferred in this reaction.