IV. Calculate AH, AS and AG at 25 C, and tell if the reaction will go spontaneously (use Table 1 and 2) m. N:(g) + 3 H:(g) - 2 NH (g) n 2 CO(g) + 0:(g) → 2 CO:(g) a 2 C:H:(g) + 50:(g) 4 CO:(g) + 2 H;0(g)
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
![AH ( kcal/mol)
AH (k]/mol)
Compound
H;0(g)
-57.8
-242
Table 1
H;O(1)
-68.3
-285
NO(R)
21.5
89.9
NO:(R)
NH3(g)
8.0
33.4
-11.0
-46.0
NH&NO (R)
HNO (aq)
SO:(R)
SO,(R)
H;SO.(aq)
CO(R)
CO:(R)
CHOH(g)
-87.3
-365
-41.4
-173
-71.0
-297
-94.5
-395
-217
-907
-26.4
-110
-94.1
-393
-57.0
-238
-530
-2215
CH:(g)
54.2
227
CH«(g)
12.5
522
CH«(R)
-20.2
-84.4
Heat of Formation of Some Common
Substances, at 25 °C and 1 atm
Substance
AS (kcal/mol K)
AS (k]/mol K)
H20(g)
0.0451
0.189
H20(1)
H2(g)
Cl:(g)
N2(g)
0:(g)
NH3(g)
CO(g)
CO:(8)
0.0167
0.087
Table 2
0.0312
0.130
0.0533
0.221
0.0458
0.189
0.0490
0.204
0.0460
0.192
0.0473
0.197
0.0511
0.213
SO:(g)
C2H2(g)
CaH«(g)
C2Ho(g)
0.0594
0.247
0.0480
0.200
0.0525
0.217
0.0549
0.225
CH3OH(g)
CH,OH(1)
0.0568
0.234
0.0303
0.125
Entropy (AS) values of some common Substances](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fbb081c07-56db-4541-b0c7-c783d7cfacb7%2F34b6d191-50c6-4ffe-a680-d26d8062f5e0%2Foqvgy3_processed.jpeg&w=3840&q=75)
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