Enter the change in internal energy (J), the change in pressure (Pa), and the change in volume (m^3) into the calculator to determine the Change in Enthalpy. 

Change in Enthalpy Formula

The following formula is used to calculate the Change in Enthalpy.

dH = dU + dP * dV

  • Where dH is the Change in Enthalpy (J)
  • dU is the change in internal energy (J) 
  • dP is the change in pressure (Pa) 
  • dV is the change in volume (m^3) 

How to Calculate Change in Enthalpy?

The following example problems outline how to calculate the Change in Enthalpy.

Example Problem #1

  1. First, determine the change in internal energy (J). In this example, the change in internal energy (J) is given as 100 .
  2. Next, determine the change in pressure (Pa). For this problem, the change in pressure (Pa) is given as  5 .
  3. Next, determine the change in volume (m^3). In this case, the change in volume (m^3) is found to be 4.
  4. Finally, calculate the Change in Enthalpy using the formula above: 

dH = dU + dP * dV

Inserting the values from above yields: 

dH = 100 + 5 * 4 = 120 (J)


Example Problem #2

Using the same method as above, determine the variables required by the equation. For this example problem, these are as follows:

change in internal energy (J) = 270

change in pressure (Pa) = 3

change in volume (m^3) = 6

Entering these given values and solving gives: 

dH = 270 + 3 * 6 = 218 (J)