Enthalpy change velocity is the enthalpy of the reactants minus the enthalpy of the products viewed as a velocity expressed in meters per second. Enthalpy change velocity is maximized the more electrons dance for every party pooping nucleon. This velocity is the exhaust velocity that an ideal rocket engine would have. The conventional reactant combination which has the lowest enthalpy change velocity is methanol and hydrogen peroxide, with an enthalpy change velocity of about three thousand eight hundred meters per second. The conventional reactant combination which has the highest enthalpy change velocity is hydrogen and oxygen, with an enthalpy change velocity of about five thousand four hundred meters per second. Evaporation has a far lower enthalpy change velocity than rocket fuel chemical reactions, typically around a thousand meters per second.

Fuel heat of formation, fuel molar ratio, mix heat, mixed carbon dioxide, mixed water, mixture mass, mixture oxidizer mix, oxidizer heat of formation, oxidizer mix, propellant heat of formation, propellant mix, unreacted fuel, unreacted oxidizer mix and water enthalpy are used to calculate the enthalpy change which is in turn used to calculate the enthalpy change velocity.

mix heat = oxidizer mix * oxidizer heat of formation + propellant mix * propellant heat of formation

reactant enthalpy = fuel molar ratio * fuel heat of formation + mixture oxidizer mix * mix heat

product enthalpy = mixed water * water enthalpy - 393509000.0 * mixed carbon dioxide + unreacted fuel * fuel heat of formation + unreacted oxidizer mix * mix heat

enthalpy change = ( reactant enthalpy - product enthalpy ) / mixture mass

enthalpy change velocity = sqrt( 2 * enthalpy change )
 
 

This is used in bipropellant rocket, tripropellant rocket, pumped rocket and rocket cost.
 
  Rocket