Answer: [tex]\Delta H^o[/tex] for the given reaction is -901.2 kJ.
Explanation: Enthalpy of the reaction is the amount of heat released or absorbed in a given chemical reaction.
Mathematically,
[tex]\Delta H_{rxn}=\Delta H_f_{(products)}-\Delta H_f_{(reactants)}[/tex]
For given reaction:
[tex]4NH_3(g)+5O_2(g)\rightarrow 4NO(g)+6H_2O(g)[/tex]
[tex]H_f_{(NH_3)}=-46.1kJ/mol[/tex]
[tex]H_f_{(O_2)}=0kJ/mol[/tex]
[tex]H_f_{(H_2O)}=-241.8kJ/mol[/tex]
[tex]H_f_{(NO)}=-91.3kJ/mol[/tex]
[tex]\Delta H_{rxn}=[6\Delta H_f_{(H_2O)}+4\Delta H_f_{(H_2O)}-[4\Delta H_f_{(NH_3)}+5\Delta H_f_{(O_2)}][/tex]
Putting values in above equation, we get:
[tex]\Delta H_{rxn}=[6mol(-241.8kJ/mol)+4mol(91.3kJ/mol)]-[4mol(-46.1kJ/mol)+5mol(0kJ/mol)][/tex]
[tex]\Delta H_{rxn}=-901.2kJ[/tex]