[单选题]
Liquid dinitrogen tetrox
-y*f)t- i:tguu:y fb dvxknc 18 2z;jeide ($N_2O_4$) is converted to gaseous nitrogen dioxide when heated, as shown in the diagram. No other molecules react or form during this reaction.
The standard enthalpy change of the reaction,ΔH$_r^θ$, is +85.8kJmol$^{-1}$.The standard enthalpy of formation of gaseous $NO_2$ , ΔH$_r^θ$($NO_2$), is +33.1kJmol$^{-1}$.
What is the standard enthalpy of formation of liquid $N_2O_4$,ΔH$_r^θ$($N_2O_4$)?
