Enthalpy Calculator

Calculate Change in Enthalpy (ΔH)









What is Enthalpy?

Enthalpy is a measure of total energy in a system. This is typically in the form of heat, but also a form of volume and pressure. Since enthalpy is a measure of the state of a system, it does not change at equilibrium. That is why we look at the change in enthalpy of a system from one state to another. The state of the system has to change in order for the enthalpy to change. This normally happens when work or energy is transferred to a system, typically through heat. Enthalpy changes in both endothermic or exothermic reactions. An endothermic reaction is an act of absorbing energy to change states, and an exothermic reaction is an act of releasing energy or heat. The change in enthalpy will be positive for endothermic and negative for exothermic.

Formula

The formula to calculate the change in enthalpy (ΔH) is:

\[ \Delta H = (Q_2 - Q_1) + p \cdot (V_2 - V_1) \]

Where:

Example

Let's say the initial internal energy (Q1) is 500 J, the final internal energy (Q2) is 800 J, the initial volume (V1) is 0.1 m3, the final volume (V2) is 0.2 m3, and the pressure (p) is 1000 Pa. Using the formula:

\[ \Delta H = (800 - 500) + 1000 \cdot (0.2 - 0.1) = 300 + 100 = 400 \text{ J} \]

So, the change in enthalpy (ΔH) is 400 J.

Extended information about "Enthalpy-Calculator"

Enthalpy Calculator for Steam

Formula: \( H = m \times h \)

Example: \( H = 2 \times 2700 \)

Enthalpy Calculator for HVAC

Formula: \( H = m \times c_p \times \Delta T \)

Example: \( H = 1.5 \times 1.005 \times 10 \)

Enthalpy Calculator for Air

Formula: \( H = m \times c_p \times \Delta T \)

Example: \( H = 2 \times 1.005 \times 15 \)

Enthalpy Calculator for Water

Formula: \( H = m \times c_p \times \Delta T \)

Example: \( H = 3 \times 4.18 \times 20 \)

Enthalpy Calculator for BTU/lb

Formula: \( H = m \times h \)

Example: \( H = 5 \times 180 \)

Enthalpy Calculator for R134a

Formula: \( H = m \times h \)

Example: \( H = 1.2 \times 250 \)

Enthalpy Calculator for Chemistry

Formula: \( \Delta H = \Delta U + P \Delta V \)

Example: \( \Delta H = 500 + 101.3 \times 0.02 \)

Enthalpy Calculator for Saturated Steam

Formula: \( H = m \times h \)

Example: \( H = 2.5 \times 2700 \)