alleryStart learning →How is enthalpy defined?
AInternal energy minus the product of pressure and volume
BInternal energy plus the product of pressure and volume
CHeat capacity times the change of temperature observed
DWork done divided by the change in volume of a system
Answer & Solution
Correct answer: B. Internal energy plus the product of pressure and volume
1. Enthalpy is the sum of internal energy and the product of pressure and volume.
2. Because internal energy, pressure and volume are all state functions, enthalpy is one too.
3. Absolute enthalpy values cannot be measured, only changes in enthalpy.
4. At constant pressure the enthalpy change equals the heat flow for the process.
5. A subtraction rather than a sum would not reduce to the heat at constant pressure.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 5 "Thermochemistry", section 5.3 Enthalpy_
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