Enter the change in internal energy, the change in volume, and the change in pressure of a reaction to calculate the total change in Enthalpy.
Enthalpy is defined as the heat absorbed by a system and the total work done while expanding. The following formula can be used.
ΔH = (Q₂ – Q₁) + p * (V₂ – V₁)
Where ΔH is the change in enthalpy
Q1/Q2 are the internal energy of the system at initial time and final time
V1/V2 are the volumes at the initial and final times
p is the constant pressure.
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 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 the act of absorbing energy to change states, and an exothermic reaction is the act of releasing energy or heat. The change in enthalpy will be positive for endothermic and negative for exothermic.
How to calculate Enthalpy
To calculate the enthalpy of a reaction, you first must know the initial energy. Energy is measured in Joules, which is typically measured from total heat.
Next, you need to measure the change in volume of the system, typically measure in liters.
Finally you need to measure the change in pressure, typically measure in Pascals.
Just enter the information in the above calculator and you have your change in Enthalpy.