HESS 'S LAW
& STANDARD ENTHALPY OF FORMATION
standard enthalpy .
enthalpy change measured at 100 kPa
change Of formation
•
and a
specified temp ( usually 298K ) ,
( Df H°) when one more of a substance is formed
from its elements in standard states .
:
formation of
CH4
-
c t / H2 →
CH4
( s)
(
g) (g)
(
graphite )
(a CO3
-
Ca t C 1-3-202 →
Call }
(s ) (s) (
9' CS )
(
graphite )
HESS 'S I.AW
The enthalpy independent of path taken in
change of a reaction is the
converting reactants into products , provided the initial and final conditions
are the same in each case .
& STANDARD ENTHALPY OF FORMATION
standard enthalpy .
enthalpy change measured at 100 kPa
change Of formation
•
and a
specified temp ( usually 298K ) ,
( Df H°) when one more of a substance is formed
from its elements in standard states .
:
formation of
CH4
-
c t / H2 →
CH4
( s)
(
g) (g)
(
graphite )
(a CO3
-
Ca t C 1-3-202 →
Call }
(s ) (s) (
9' CS )
(
graphite )
HESS 'S I.AW
The enthalpy independent of path taken in
change of a reaction is the
converting reactants into products , provided the initial and final conditions
are the same in each case .
