Given the following standard reaction enthalpies: And the standard enthalpy of formation of ozone,+142.7 kJ.mol ^- ¹,calculate the standard reaction enthalpy for the reaction NO(g)+ O(g)$\rightarrow$ NO₂(g)

Question

Quizplus · Accepted Answer

To calculate the standard reaction enthalpy for the given reaction, we need to use Hess's law and manipulate the given standard reaction enthalpies to obtain the desired enthalpy. The given enthalpies are:
1. NO(g) + O3(g) → NO2(g) + O2(g) ΔH° = -197.8 kJ/mol
2. O3(g) → 3O2(g) ΔH° = -142.7 kJ/mol
3. 2NO(g) + O2(g) → 2NO2(g) ΔH° = -114.0 kJ/mol

We need to combine these reactions in a way that cancels out the O2 and forms N2O5. Multiplying the first reaction by 2 and adding it to the third reaction gives:
2NO(g) + 2O3(g) → 2NO2(g) + 2O2(g) ΔH° = -395.6 kJ/mol
2NO(g) + O2(g) → 2NO2(g) ΔH° = -114.0 kJ/mol
----------------------------
2O3(g) + O2(g) → N2O5(g) ΔH° = -309.6 kJ/mol

Note that we have used the fact that the enthalpy change is directly proportional to the number of moles of reactants and products involved in the reaction. The coefficients in the balanced chemical equation give the necessary conversion factors.

Therefore, the standard reaction enthalpy for the given reaction is +309.6 kJ/mol (note the sign change due to flipping the equation). The answer is closest to choice A: +306 kJ/mol.

Given the Following Standard Reaction Enthalpies: and the Standard →\rightarrow→

Given the Following Standard Reaction Enthalpies: and the Standard $\rightarrow$