Enthelpy = internal energy+pressure*volume

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Enthalpy is defined as the sum of internal energy and the product of pressure and volume. While internal energy, pressure, and volume can be determined for a specific state, absolute enthalpy cannot be calculated due to its dependence on temperature and the reference point chosen for measurement. Instead, only changes in enthalpy can be calculated, which are crucial for understanding energy transfer during chemical reactions, particularly when bonds are broken. The discussion highlights that the change in pressure and volume, or ΔPV, is relevant when considering work done during expansion against atmospheric pressure.
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My chem book says that

Enthalpy = internal energy+pressure*volume

However it says that enthalpy for a particular state cannot be calculated. Only the enthalpy change can be calculated. This has me confused.
Aren't internal energy, pressure and volume calculabe for a particular state? Then why can't we calculate absolute enthalpy?
 
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Enthaply is used to calculate how much energy is taken in or released by a reaction where bonds have been broken (well all reactions really need bonds to brake but still...).

Enthaply, however, also depends on the temperature (if I am correct) and ,thus, it is only possible to have an equation for the change.

This might help or checking the rest of these might as well.

The Bob (2004 ©)
 
It should be change in PV, or \Delta PV, the work in expansion against the atmosphere
 

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