How do you perform an energy balance on a chemical reactor?

Steady-state energy balance: Q - W = sum(n_out*H_out) - sum(n_in*H_in), including heat of reaction via enthalpies of formation. Steps: calculate inlet enthalpy (sensible heat from reference), calculate outlet enthalpy including product species, heat of reaction appears as enthalpy difference. For exothermic: outlet enthalpy > inlet, Q negative (heat removal needed). For adiabatic: Q=0, solve for outlet temperature. Include: phase changes, mixing effects if significant, and temperature-dependent properties. Reference state consistency is critical.