Thermodynamics
Enthalpy
Heat content at constant pressure. ΔH = Q_p for constant pressure processes.
Variables
HJ
Enthalpy
Total heat content
UJ
Internal energy
Internal energy
PPa
Pressure
System pressure
Vm³
Volume
System volume
Derivation
H = U + PV. At constant P: dH = dU + PdV = δQ. So ΔH = Q at constant pressure.
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Common questions
What is the Enthalpy formula?
Enthalpy is written H = U + PV. Heat content at constant pressure. ΔH = Q_p for constant pressure processes. It belongs to Thermodynamics, under First Law.
What are the units in H = U + PV?
In SI units, H is enthalpy, measured in kg·m²/s²; U is internal energy, measured in kg·m²/s²; P is pressure, measured in kg/(m·s²); V is volume, measured in m³.
How is the Enthalpy formula derived?
H = U + PV. At constant P: dH = dU + PdV = δQ. So ΔH = Q at constant pressure. The result is H = U + PV.