Nitrogen reacts with hydrogen to form ammonia according to the equation below. Standard Enthalpies of Formation Substance DHf (kJ/mol) C2 H2 (g) –26.7 NH3 (g) –46.19 HBr (g) 236.23 HCl (g) –92.30 HF (g) –268.6 HI (g) 25.9 NaCl (s) –411.0 Based on the equation and the information in the table, what is the enthalpy of the reaction? Hrxn = 46.19 kJ Hrxn = –46.19 kJ Hrxn = 92.38 kJ Hrxn = –92.38 kJ