Enthalpy change is the enthalpy of the reactants per unit mass minus the enthalpy of the products per unit mass expressed in joules per kilogram. Enthalpy change is maximized the more electrons dance for every party pooping nucleon. The conventional reactant combination which has the lowest enthalpy change is methanol and hydrogen peroxide, with an enthalpy change of about seven million joules per kilogram. The conventional reactant combination which has the highest enthalpy change is hydrogen and oxygen, with an enthalpy change of about fourteen million joules per kilogram.

Evaporation has a far lower enthalpy change than rocket fuel chemical reactions, typically around five hundred thousand joules per kilogram. 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 - 393,509,000 * 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.
 
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