The reaction of cr2+(aq) with cr2o2−7(aq) in acid solution to form cr3+(aq). calculate δg∘rxn.

The correct answer is -1059.45 kJ.

Explanation:

The balanced equation is:

6Cr₂⁺ + Cr₂O₇²⁻ + 14H⁺ ⇒ 8Cr₃⁺ + 7H₂O

In the mentioned reaction 6 electrons are transferred

By calculating Ecell with the use of reduction potential of each cell:

Ecell = Eox + Ered

Ered = 0.50V

Eox = -Ered = -(-0.50V) = 0.50V

Ered = 1.33V

Ecell = 0.50V + 1.33V

Ecell = 1.83V

Now in order to calculate ΔG

n = 6, Faraday constant (f) = 9.68470 × 10⁴ = 96847 C mol⁻¹

ΔG = -nFE

ΔG = -6 × 96487 C mol-1 × 1.83V

ΔG = -1059.42 KJ

The relation between ΔG and ΔG°rxn

ΔG = ΔG° + RTlnQ

Under the standard condition Q = 1 and ΔG = ΔG°

Thus,

ΔG°rxn = ΔG = -1059.42 KJ