ENTHALPY CHANGES
Enthalpy change is the heat
energy
transferred between a system and
its
surroundings at constant pressure .
system
:
reactants & products
surroundings everything : else
standard enthalpy conditions
}
•
100hPa (just > 1 atm )
•
298K
H%gk
standard enthalpy change of a reaction ( rH°) is measured at
100K Pa and a stated temperature , usually 298K .
Haber process
↳ °
-92k/ md
"
Nz t H2T 2NH } Dr H
=
"
↳ IN2 1- & He ≥ NH } since half .
Dr -11° = -46k /Md
EXOTHERMIC : negative change C- DH ) releases to
surroundings
.
energy from system
ENDOTHERMIC : positive
change ( + AH ) absorbs ,
energy from surroundings
↑
system
products
.
reactants
DH9
6DH reactants
Products
exo endo
Enthalpy change is the heat
energy
transferred between a system and
its
surroundings at constant pressure .
system
:
reactants & products
surroundings everything : else
standard enthalpy conditions
}
•
100hPa (just > 1 atm )
•
298K
H%gk
standard enthalpy change of a reaction ( rH°) is measured at
100K Pa and a stated temperature , usually 298K .
Haber process
↳ °
-92k/ md
"
Nz t H2T 2NH } Dr H
=
"
↳ IN2 1- & He ≥ NH } since half .
Dr -11° = -46k /Md
EXOTHERMIC : negative change C- DH ) releases to
surroundings
.
energy from system
ENDOTHERMIC : positive
change ( + AH ) absorbs ,
energy from surroundings
↑
system
products
.
reactants
DH9
6DH reactants
Products
exo endo
