Calculate enthalpy change using multiple methods: ΔH = ΔU + PΔV, ΔH = Q (at constant pressure), or ΔH = m × c × ΔT. Free online thermodynamics calculator for physics, chemistry, and engineering.
Calculate enthalpy change using different methods: ΔH = ΔU + PΔV, ΔH = Q, or ΔH = m × c × ΔT
Formula:
ΔH = ΔU + PΔV
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Enthalpy is one of the most important thermodynamic properties in physics and chemistry, representing the total heat content of a system. Whether you're studying thermodynamics, working on chemical reactions, or designing thermal systems, understanding enthalpy is essential. Our Enthalpy Calculator makes it easy to calculate enthalpy change using multiple methods, making it perfect for various applications in physics, chemistry, and engineering.
Enthalpy (H) is defined as the sum of internal energy (U) and the product of pressure (P) and volume (V): H = U + PV. For most practical purposes, we work with enthalpy change (ΔH), which represents the heat transferred at constant pressure. This makes enthalpy particularly useful for analyzing chemical reactions, phase changes, and heat transfer processes.
Our Enthalpy Calculator offers three different calculation modes to suit various scenarios:
Select your preferred calculation mode, enter the known values, choose your units, and click Calculate to get instant results with step-by-step solutions.
Enthalpy can be calculated using several fundamental formulas:
H = U + PV
Where: H = enthalpy, U = internal energy, P = pressure, V = volume
ΔH = ΔU + PΔV
Where: ΔH = enthalpy change, ΔU = internal energy change, P = pressure, ΔV = volume change
ΔH = Q (at constant pressure)
Where: ΔH = enthalpy change, Q = heat transfer
ΔH = m × c × ΔT
Where: ΔH = enthalpy change, m = mass, c = specific heat capacity, ΔT = temperature change
Enthalpy calculations are essential in numerous real-world applications:
It's crucial to use consistent units in your enthalpy calculations:
Tip: Our calculator automatically converts between different units, so you can mix units as needed. The calculator ensures all calculations are performed in consistent base units internally.
A system undergoes a process where internal energy changes by 500 J, pressure is 101325 Pa, and volume increases by 0.001 m³. What is the enthalpy change?
ΔH = ΔU + PΔV = 500 J + (101325 Pa × 0.001 m³) = 601.325 J
At constant pressure, 2500 J of heat is transferred to a system. What is the enthalpy change?
ΔH = Q = 2500 J (at constant pressure)
Calculate the enthalpy change when 2 kg of water (specific heat = 4184 J/(kg·K)) is heated from 20°C to 80°C.
ΔH = m × c × ΔT = 2 kg × 4184 J/(kg·K) × 60 K = 502,080 J = 502.08 kJ
While enthalpy and internal energy are related, they have distinct meanings:
The key difference is that enthalpy accounts for the work done by or on the system due to volume changes at constant pressure. This makes enthalpy particularly useful for processes occurring at constant pressure, which is common in many real-world applications.
For constant pressure processes, enthalpy change equals heat transfer (ΔH = Q), making it easier to measure and calculate than internal energy change alone.
Enthalpy plays a crucial role in chemical thermodynamics:
Understanding enthalpy changes helps predict whether reactions will occur spontaneously and how much energy they will release or require.
Enthalpy (H) is a thermodynamic property representing the total heat content of a system, defined as H = U + PV. It's important because at constant pressure, enthalpy change equals heat transfer, making it easier to measure and calculate than internal energy alone. Enthalpy is essential for analyzing chemical reactions, phase changes, and heat transfer processes.
Internal energy (U) is the total energy within a system. Enthalpy (H) is internal energy plus the product of pressure and volume (H = U + PV). For constant pressure processes, enthalpy change equals heat transfer, making enthalpy more convenient to work with in many practical applications.
Use ΔH = Q when working at constant pressure, as this is the most common scenario in chemical reactions and many physical processes. Use ΔH = ΔU + PΔV when you need to account for both internal energy change and pressure-volume work, or when you have specific values for internal energy change, pressure, and volume change.
Yes, enthalpy change (ΔH) can be negative. A negative enthalpy change indicates an exothermic process that releases heat to the surroundings. A positive enthalpy change indicates an endothermic process that absorbs heat from the surroundings.
Enthalpy is typically measured in energy units: Joules (J), Kilojoules (kJ), Calories (cal), or BTU. Our calculator supports all common energy units and automatically converts between them. Ensure consistency with other units in your calculation (pressure in Pa, volume in m³, etc.).
For chemical reactions at constant pressure, enthalpy change equals the heat of reaction. You can calculate it using standard enthalpies of formation, or measure it directly using calorimetry. Our calculator's constant pressure mode (ΔH = Q) is perfect for this application.
Understanding enthalpy is fundamental to thermodynamics, chemistry, and engineering. Our Enthalpy Calculator simplifies these calculations, making it easy to solve problems involving heat content, energy changes, and thermal processes.
Ready to explore more thermodynamics concepts? Check out our other calculators like the Specific Heat Calculator for heat capacity calculations, or the Charles's Law Calculator for ideal gas law calculations that often complement enthalpy analysis.
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