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

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.