To have a standard enthalpy of formation referenced to 0 J/mol,the substance must:
I.be a simple substance (chemical element)
II.be in its most stable form
III.be under 1 bar of pressure
IV.have a concentration of 1.0000 M
A)I,III,IV
B)I,II,III
C)II,IV
D)I,III
E)II,III,IV

Question

Quizplus · Accepted Answer

The requirement for a standard enthalpy of formation referenced to 0 J/mol is that the substance must be in its most stable form. Additionally, it must be a simple substance (chemical element) to have a unique enthalpy value. The pressure and concentration of the substance do not affect the value of enthalpy of formation, so options III and IV can be excluded.

To Have a Standard Enthalpy of Formation Referenced to 0