Question

Choose all the molecules with zero standard-enthalpy-of-formation (ΔH⁰f=0)

a.C(graphite)
b.K(s)
c.Fe(s)
d.H₂O(g)
e.N₂(g)
f.FeCl₂(s)
g.H₂O(l)
h.O₂(g)

Answer 1

The standard enthalpy of formation of any element in its standard state is zero by definition. For molecules in the given list, C(graphite), H₂O(g), and N₂(g) have a standard enthalpy of formation of zero.

Step-by-step explanation:

The standard enthalpy of formation of any element in its standard state is zero by definition. For example, oxygen exists as O₂(g), hydrogen exists as H₂(g), and carbon exists as graphite (C). In the given list, molecules with a standard enthalpy of formation of zero include C(graphite), H₂O(g), and N₂(g).