Use Hess's law to calculate ΔG°rxn using the following information. NO(g) + O(g) → NO2(g) ΔG°rxn = ? 2 O3(g) → 3 O2(g) ΔG°rxn = +489.6 kJ O2(g) → 2 O(g) ΔG°rxn = +463.4 kJ NO(g) + O3(g) → NO2(g) + O2(g) ΔG°rxn = -199.5 kJ

Answer : The value of is, -676 kJ

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

The given main reaction is,

The intermediate balanced chemical reaction will be,

(1)    

(2)      

(3)    

Now we are reversing the reaction 1 and 2 and multiplying reaction 3 by 2 and then adding all the equations, we get :

(1)    

(2)      

(3)    

The overall reaction is:

Now we are dividing the overall reaction by 2, we get:

Thus, the value of is, -676 kJ