Standard Rxn Enthalpies for liquids and solids

[Daisylookinland]

In the notes, Dr. Lavelle wrote "for a pure liquid or solid it [the standard rxn enthalpy] is the pure L or S"
Can someone explain what this means?

[Laura Gong 3H]

It just means that the most stable form (its standard state) of a pure liquid or solid is liquid or solid.

[Kayla Vo 1B]

To add on, the standard state basically is the physical state (solid, liquid, or gas) that a substance would be in under standard conditions (1.00 atm and 25 degrees Celsius). So, the standard state for carbon is solid and for water is liquid.