In this enthalpy calculator, we will show you how to find the enthalpy of a system in just a few simple steps.
We will also help you understand what enthalpy really means, and how the formula works while we’re at it.
What is enthalpy?
How is it related to internal energy, pressure, and volume?
How do you calculate enthalpy in real-world situations? Find all the answers right here! By the end, you’ll be able to solve enthalpy problems confidently and understand its practical applications.
Enthalpy Calculator
Understanding the Formula: H = U + PV
Enthalpy (H) is a measure of the total energy of a thermodynamic system. It combines the internal energy (U) of the system and the energy associated with the system’s pressure (P) and volume (V).
- H = Enthalpy (Joules, J)
- U = Internal Energy of the system (J)
- P = Pressure of the system (Pascals, Pa)
- V = Volume of the system (m³)
The term PV represents the work done by the system when it expands against the surrounding pressure. This formula is widely used in thermodynamics to understand energy changes in chemical reactions, engines, and more.
Real-World Applications of Enthalpy
| Application | Description |
|---|---|
| Chemical Reactions | Calculating energy released or absorbed during reactions. |
| Steam Engines | Determining work done by steam expansion. |
| HVAC Systems | Energy calculations for heating and cooling air and fluids. |
| Combustion Engines | Evaluating energy efficiency of fuel combustion. |
Enthalpy Calculation: Step-by-Step Example
Example:
A gas in a piston has an internal energy of U = 5000 J. The gas is at a pressure of P = 200 kPa and occupies a volume of V = 0.02 m³. Calculate the enthalpy of the gas.
Solution:
- Internal Energy, U = 5000 J
- Pressure, P = 200 kPa = 200,000 Pa
- Volume, V = 0.02 m³
Enthalpy, H = U + PV
PV = P × V = 200,000 × 0.02 = 4,000 J
H = U + PV = 5000 + 4000 = 9000 J
Enthalpy, H = 9,000 Joules (J)
Reference Table: Units & Conversion
| Quantity | Unit | Conversion |
|---|---|---|
| Pressure (P) | Pa, kPa | 1 kPa = 1,000 Pa |
| Volume (V) | m³ | 1 m³ = 1,000 L |
| Energy (U, H, PV) | Joules (J) | 1 kJ = 1,000 J |
Graphical Representation of Enthalpy
FAQs
What is enthalpy?
In simple words, enthalpy is the total energy of a system. It includes the internal energy plus the energy from pressure and volume.
How is enthalpy different from internal energy?
Internal energy is just the energy inside the system. Enthalpy adds the energy from the system’s pressure and volume too.
Where is enthalpy used in real life?
Enthalpy is used in chemical reactions, engines, steam systems, and even heating and cooling systems to see how energy changes.