Question

Explain Enthalpy of a substance​

Answer 1

✪ Enthalpy of a substance✪

★Every substance has a fixed value of enthalpy under any particular state its exact value cannot be calculated but it has some finite fixed value.

★Enthalpy of one mole of a substance called molar enthalpy in any particular state can be assigned symbol.

★Molar enthalpy of a substance under standard conditions is called standard molar enthalpy of a substance.

★Molar standard enthalpy of water vapours at 398 Keval represented as H° and standard standard enthalpy of liquid water at 398 k will be represented as Hm°

Answer 2

Explanation:

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Enthalpy of a substance is defined as the internal energy of the substance + pressure energy per unit mass of the substance. The reason for defining such kind of relationship is that under constant pressure system the change of this property (enthalpy) denotes the heat added or removed from the system.