The amino acid glycine, C2H5NO2, is one of the compounds used by the body to make proteins. The equation for its combustion is 4C2H5NO2(s) + 9O2(5) → 8CO2(g) +10H2O(1) +2N2(g) For each mole of glycine that burns, 973.49 kJ of heat is liberated. Use this information, plus values of AH° for the products of combustion, to calculate AH for glycine. AH° = i ! kJ/mol
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.
![In the recovery of iron from iron ore, the reduction of the ore is actually accomplished by reactions involving carbon monoxide. Use the
following thermochemical equations,
Fe,O3() + 3CO(g) 2Fe(s) + 3CO,(g)
AH° = -28 kJ
3Fe,O3() + CO(g) 2Fe,O4(0) + CO,(g)
AH° = -59 kJ
Fe,O4(6) + CO(g)-
3FeO(s) + CO,(g)
AH° = +38 kJ
The AH° for the reaction
FeO() + CO(g) Fe(s) + CO2(g)
is -16.8 kJ. Use this data and the data in the following table to calculate the value of AH° for FeO.
Standard Enthalpies of Formation of Typical Substances
AH; (KI mol-1)
AH (KI mol-1)
AH (KI mol-)
)
AH; (KI mol-1)
Substance
Substance
Substance
Substance
Ag(s)
H,O,(/)
-187.6
CH(g)
-84.667
NO(g)
90.37
AgBr()
-100.4
HBrg)
-36
CH,OH(/)
-277.63
NO,(g)
33.8
AgC()
- 127.0
HC(g)
-92.30
Ca(s)
N,0(g)
81.57
AIG)
HI(g)
26.6
CaBrz6)
-682.8
N,Odg)
9.67
Al,O,()
-1669.8
HNO,()
-173.2
CaCO)
- 1207
N,0;(g)
11
Ct) (graphite)
H,SO,)
-811.32
CaCl()
-795.0
Na(s)
CO(e)
-110.5
HC,H,0,)
NaHCO,6)
-947.7
-487.0
CaO()
--635.5
CO:)
-393.5
Hg(/)
Ca(OH)20)
-986.59
Na,CO,()
-1131
CH,(g)
-74.848
Hg(g)
60.84
CaSO,()
- 1432.7
NaCl(s)
-411.0
CH,C(g)
-82.0
1,0)
CasO, H,0()
- 1575.2
NAOH())
-426.8
CHI(g)
Na SO,)
14.2
K()
CaSO, 2H,0G)
- 2021.1
-1384.5
CH,OH()
CO(NH),) (urea)
CONH(ag)
-238.6
KCI)
-435.89
Ch(e)
-333.19
K,SO,()
- 1433.7
Fe(s)
Pb(s)
-391.2
Na(g)
Fe,O,4)
-822.2
PbO()
-219.2
CH(g)
226.75
NH3(g)
-46.19
H2(g)
CH.(g)
52.284
NH,CI()
-315.4
H,O(g)
-241.8
So-(g)
-296.9
H,O)
-285.9
So,(g)
-395.2
Express the answer in units of kilojoules per mole.
AH;° = i
kJ/mol](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fd98adfa0-de04-4d6f-8346-bc2009db9cef%2F16baea96-afb2-4314-b9e8-70188df241f6%2Fyzc06xs_processed.png&w=3840&q=75)
![The amino acid glycine, C2H5NO2, is one of the compounds used by the body to make proteins. The equation for its combustion is
4C2H5NO2(s) + 902(g) → 8CO2(g) +10H2O(1) +2N2(g)
For each mole of glycine that burns, 973.49 kJ of heat is liberated. Use this information, plus values of AH° for the products of
combustion, to calculate AH° for glycine.
ΔΗ-
i
! kJ/mol](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fd98adfa0-de04-4d6f-8346-bc2009db9cef%2F16baea96-afb2-4314-b9e8-70188df241f6%2Ffs1r6r_processed.png&w=3840&q=75)
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