Question

Consider the oxidation of NO to NO2:

NO(g)+12O2(g)→NO2(g)
Standard thermodynamic quantities for selected substances at 25∘C
Substance ΔH∘f(kJ/mol) S∘(J/(mol⋅K))
NO(g) 91.3 210.8
NO2(g) 33.2 240.1
O2(g) 0 205.2
Calculate ΔG∘rxn at 55 ∘C.
Express the free energy change to three significant figures and include the appropriate units
2. One of the reactions that occurs within a catalytic converter in the exhaust pipe of a car is the simultaneous oxidation of carbon monoxide and reduction of NO (both of which are harmful pollutants):
2CO(g)+2NO(g)→2CO2(g)+N2(g)

Answer 1

To calculate the standard Gibbs free energy change (ΔG°rxn) at 55 °C for the oxidation of NO to NO2, use the equation ΔG°rxn = ΔH°rxn - TδS°rxn, where ΔH°rxn is the change in enthalpy and TδS°rxn is the change in entropy.

Step-by-step explanation:

The question asks to calculate the standard Gibbs free energy change (ΔG°rxn) at 55 °C for the oxidation of NO to NO2. To calculate ΔG°rxn, we need to use the equation ΔG°rxn = ΔH°rxn - TδS°rxn, where ΔH°rxn is the change in enthalpy and TδS°rxn is the change in entropy.

First, calculate ΔH°rxn using the enthalpy of formation values for the reactants and products. Then, calculate the change in entropy (δS°rxn) by subtracting the sum of the entropy of the reactants from the sum of the entropy of the products. Finally, substitute the values into the equation to calculate ΔG°rxn at 55 °C.