Problem: A gas-phase reaction was run in an apparatus designed to maintain a constant pressure.Using data from Appendix C in the textbook, determine H for the formation of one mole of the product.

FREE Expert Solution

We’re being asked to determine the standard enthalpy change of formation (ΔH˚rxn) for NO


Recall that ΔH˚rxn can be calculated from the enthalpy of formation (ΔH˚f) of the reactants and products involved


Hrxn= Hf products - Hf reactants


The chemical equation for that reaction is:

N2(g) + O2(g)→ NO(g)


This equation is not yet balanced. To balance it, we have to make sure that the number of elements on both sides is equal.


Balance N: We have 1 N2 on the reactant side and 1 O on the product side – add a coefficient of 2 to NO:

N2(g) + O2(g)→ 2 NO

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Problem Details

A gas-phase reaction was run in an apparatus designed to maintain a constant pressure.

A piston applies pressure to a cylinder containing two O2 molecules and two N2 molecules.  This leads to four NO molecules.

Using data from Appendix C in the textbook, determine H for the formation of one mole of the product.

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Based on our data, we think this problem is relevant for Professor Graham's class at ARIZONA.