The Enthalpy calculator compute the enthalpy energy based on the internal energy, pressure and volume.
INSTRUCTIONS: Choose units and enter the following:
Enthalpy(H): The calculator returns the enthalpy in joules. However this can be automatically converted to compatible units via the pull-down menu.
The enthalpy[1] equation is always associated with the first law of thermodynamics[3], which states that energy can not be created or destroyed, thus it is to calculate the energy released or absorbed by the system. The system[4] is what we're interested in (such as the substance or matter), the environment around the system is called it's surroundings[5]. Energy is transferred between the two and the enthalpy equation is the way to measure the energy change in the form of heat[6].
The enthalpy equation is defined by
H = U + P•V
where:
The enthalpy equation is a state function, which means its dependent on its variables, specifically temperature, pressure and internal energy[7]. If temperature and pressure were to be kept constant the equation will be ΔH=ΔU+PΔV. From this equation we can see that the enthalpy is dependent on the change of volume and internal energy. If pressure is kept constant than the equation becomes ΔH=q, from this we can observe whether the system absorbs or releases heat
[1]https://en.wikipedia.org/wiki/Enthalpy
[2]Whitten, et al. 10th Edition. Pp.577
[3]https://en.wikipedia.org/wiki/First_law_of_thermodynamics
[4]https://en.wikipedia.org/wiki/Thermodynamic_system
[5]https://en.wikipedia.org/wiki/Thermodynamic_system
[6]https://en.wikipedia.org/wiki/Heat
[7]http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/inteng.html