Question

The following reactions are important ones in catalytic converters in automobiles. Calculate ΔG∘ for each at 298 K. Predict the effect of increasing temperature on the magnitude of ΔG∘.

A. 2CO(g)+2NO(g)→N2(g)+2CO2(g)

B. 5H2(g)+2NO(g)→2NH3(g)+2H2O(g)

C. 5H2(g)+2NO(g)→2NH3(g)+2H2O(g)

D. 2H2(g)+2NO(g)→N2(g)+2H2O(g)

E. 2NH3(g)+2O2(g)→N2O(g)+3H2O(g)

Answer 1

Delta G at standard condition ( Temp = 298 K, P = 1 bar) of a reaction is calculated as Delta G of product         - Delta G of the reactant at standard condition.

all the values of the Delta G of formation of the species is teken from net search.

A ) 2CO(g)+2NO(g)→N2(g)+2CO2(g)

Standard Free Energy of Formation of CO₂(g) = -394.4 kj/mole

Standard Free Energy of Formation of N₂(g) = 0 kj/mole

Standard Free Energy of Formation of CO(g) = -137.2 kj/mole

Standard Free Energy of Formation of NO(g) = 86.6 kj/mole

B) 5H2(g)+2NO(g)→2NH3(g)+2H2O(g)

Standard Free Energy of Formation of H₂(g) = 0 kj/mole

Standard Free Energy of Formation of NO(g) = 86.6 kj/mole

Standard Free Energy of Formation of NH3(g) = -16.671 kj/mole

Standard Free Energy of Formation of H2O (g) = -228.57 kj/mole

C) 5H2(g)+2NO(g)→2NH3(g)+2H2O(g)

Standard Free Energy of Formation of H₂(g) = 0 kj/mole

Standard Free Energy of Formation of NO(g) = 86.6 kj/mole

Standard Free Energy of Formation of NH3(g) = -16.671 kj/mole

Standard Free Energy of Formation of H2O (g) = -228.57 kj/mole

D) 2H2(g)+2NO(g)→N2(g)+2H2O(g)

Standard Free Energy of Formation of H₂(g) = 0 kj/mole

Standard Free Energy of Formation of NO(g) = 86.6 kj/mole

Standard Free Energy of Formation of N₂(g) = 0 kj/mole

Standard Free Energy of Formation of H2O (g) = -228.57 kj/mole

E) 2NH3(g)+2O2(g)→N2O(g)+3H2O(g)

Standard Free Energy of Formation of NH3(g) = -16.671 kj/mole

Standard Free Energy of Formation of O₂(g) = 0 kj/mole

Standard Free Energy of Formation of N2O (g) = 103.7 kj/mole

Standard Free Energy of Formation of H2O (g) = -228.57 kj/mole

• if then reaction is non - sponteneous
• if then reaction is sponteneous

for temperature variation, we need the value, which is not given.