Home
Back
Enthalpy Equation:
| From: | To: |
The enthalpy equation (ΔH = ΔU + PΔV) relates the change in enthalpy (ΔH) to the change in internal energy (ΔU) and the work done by the system (PΔV). Enthalpy is particularly useful in thermodynamics for studying heat transfer in chemical reactions and physical changes at constant pressure.
The calculator uses the enthalpy equation:
Where:
Explanation: The equation shows that enthalpy change equals the internal energy change plus the pressure-volume work done by the system.
Details: Enthalpy is crucial in thermodynamics for understanding heat changes in chemical reactions, phase transitions, and other processes occurring at constant pressure. It's widely used in chemical engineering, physical chemistry, and materials science.
Tips: Enter all values in the specified units. The calculator automatically converts the pressure-volume work term to kJ for consistency with the internal energy term.
Q1: What's the difference between enthalpy and internal energy?
A: Internal energy (U) is the total energy of a system, while enthalpy (H) includes both internal energy and the energy needed to make room for the system by displacing its environment (PV term).
Q2: When is enthalpy particularly useful?
A: Enthalpy is most useful for processes occurring at constant pressure, which is common in open systems (like most chemical reactions).
Q3: What are typical units for enthalpy?
A: In chemistry, kJ or kJ/mol are common. In engineering, J or kJ are typically used for specific calculations.
Q4: How does this relate to heat capacity?
A: At constant pressure, the heat capacity (Cp) relates directly to enthalpy changes (ΔH = CpΔT).
Q5: What about for ideal gases?
A: For ideal gases, enthalpy depends only on temperature, as the internal energy does.