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3 NO2(g)   +   H2O(l)   →   2 HNO3(l)   +   NO(g)    ΔrH = -72.0 kJ, calculate the molar enthalpy of reaction, rH for:  NO2(g)        

5 years ago

Answered By Leonardo F

This is a question about the number of moles of NO2 involved in the reaction. Since the chemical equation is already balanced and the enthalpy variation of the reaction is -72 kJ/mol for 3 moles reacted of NO2, in order to calculate the molar enthalpy of reaction for NO2, we have to do this calculation:

 $\text{Δ}H_{molar}NO_{2\left(g\right)}=\frac{\text{Δ}_rH}{3}=\frac{-72}{3}=-24$ΔHmolarNO2(g)=ΔrH3 =723 =24 kJ/mol

This means that, for every mol of NO2(g) reacted, the reaction process releases 24 kJ of heat energy, since it is exothermic.