Standard State and Enthalpy of Formation, Gibbs Free Energy of Formation, Entropy and Heat Capacity (original) (raw)

The term standard state is used to describe a reference state for substances, and is a help in thermodynamical calculations (as enthalpy, entropy and Gibbs free energy calculations). The superscript degree symbol (°) indicates that substances are in their standard states. (ΔH°, ΔG°, S°.....)

Definitions of standard states:

Note! Standard state is NOT the same as standard temperature and pressure (STP) for a gas, and must not be confused with this term.

Enthalpy is a state function, defined by the internal energy (E), the pressure (P) and volume (V) of a system:

H = E + PV and ΔH = ΔE + Δ(PV)

For enthalpy, there are no method to determine absolute values, only enthalpy changes (ΔH values) can be measured. Then it is important to have a common and well defined reference state. Since enthalpy is a state function, a change in enthalpy does not depend on the pathway between two states.

Hess's law: In going from a particular set of reactants to a particular set of products, the change in enthalpy is the same whether the reaction takes place in one step or in a series of steps.

At constant pressure: ΔH = qp (qp = heat from or to the chemical system at constant pressure, q is also called heat of reaction)

Exothermic reaction: negative ΔH (heat transferred to the surroundings from the system)

Endothermic reaction: positive ΔH (heat adsorbed by the system from the surroundings)

The standard enthalpy of formation (ΔH0f) of a compound is the change in enthalpy that accompanies the formation of 1 mole of a compound from its elements with all substances in their standard states.

The table below shows the standard enthalpy of formation, the standard Gibbs free energy of formation, standard entropy and molar heat capacity at constant pressure of several inorganic compounds.

See also Standard enthalpy of formation, Gibbs free energy of formation, entropy and molar heat capacity of organic substances and Thermodyamics key values internationally agreed for tabulation of more of the same type of values

Substances - Standard State and Enthalpies of Formation, Gibbs Free Energies of Formation, Entropies and Heat Capacities

Substance ΔH0f @25°C (kJ/mol) ΔG0f @25°C (kJ/mol) S0 @25°C (J/(molK)) Cp @25°CJ/(mol K)
Ag(g) 284.9 246 173 20.8
Ag(s) 0 0 42.6 25.4
Ag+(aq) 105.8 77.1 73.5
AgCN(s) 146 156.9 107.2 66.7
Ag2CO3(s) -505.8 -436.8 167.4 112.3
AgNO3(s) -124.4 -33.4 140.9 93.1
Ag2O(s) -31.1 -11.2 121.3 65.9
Ag2S(s) -32.6 -40.7 144 76.5
AgBr(s) -100.4 -96.9 107.1 52.4
AgCl(s) -127.0 -109.8 96.3 50.8
AgF(s) -204.6 -187 84
AgI(s) -61.8 -66.2 115.5 56.8
Al(g) 330 289.4 164.6 21.4
Al(s) 0 0 28.3 24.2
Al2O3(s) -1675.7 -1582.3 50.9 79.0
AlF3(s) -1510.4 -1431.1 66.5 75.1
AlI3(s) -302.9 195.9
AlBr3(s) -527.2 180.2 100.6
AlCl3(s) -704.5 -628.11 112.3 91.1
Al(OH)3(s) -1277
Al(OH)4-(aq) -1490 -1297 117
AlPO4(s) -1733.8 -1617.9 90.8 93.2
Ar(g) 0 154.9 20.8
B(s) 0 0 5.9 11.1
B(g) 565 521.0 153.4 20.8
BH(g) 442.7 412.7 171.8 29.2
BH3(g) 89.2 93.3 188.2 36.0
B2S3(s) -240.6 100.0 111.7
Ba(g) 180 146 170.2
Ba(s) 0 0 62.5 28.1
BaCO3(s) -1213.0 -1134.4 112.1 86.0
BaH2(s) -177 -138.2 63.0
BaBr2(s) -757.3 -736.8 146.0
BaCl2(s) -855 -806.7 123.7 75.1
BaF2(s) -1207.1 -1156.8 96.4 71.2
BaI2(s) -602.1 -597 167.0
BaO(s) -548.0 -520.3 72.1 47.3
BaSO4(s) -1473.2 -1362.2 132.2 101.8
Be(g) 324 286.6 136.3 20.8
Be(s) 0 0 9.5 13.4
BeBr2(s) -353.5 108 69.4
BeCl2(s) -490.4 -445.6 75.8 62.4
BeF2(s) -1026.8 -979.4 53.4 51.8
BeI2(s) -192.5 121 71.1
BeO(s) -609.4 -580.1 13.8 25.6
Be(OH)2(s) -902.5 -815.0 45.5 62.1
BeSO4(s) -1205.2 -1093.8 77.9 85.7
Bi(g) 207.1 168.2 187 20.8
Bi(s) 0 0 56.7 25.5
Bi2O3(s) -573.9 -493.7 151.5 113.5
BiCl3(s) -379.1 -315.0 177.0 105.0
Br-(aq) -121.4 -104.0 82.6
Br(g) 111.9 82.4 175 20.8
Br2(g) 30.9 3.1 245.5 36.0
Br2(l) 0 0 152.2 75.7
BrCl(g) 14.6 -1 240.1 35.0
BrF(g) -93.8 -109.2 229 33.0
BrF3(g) -1136 1119.4 254.4 66.6
C(g) 716.7 671.3 158.1 0.8
C(s, diamond) 1.9 2.9 2.4 6.1
C(s, graphite) 0 0 5.7 8.5
CBr4(g) 83.9 67 358.1
CBr4(s) 29.4 47.7 212.5
CCl2F2(g) -477.4 -439.4 300.8
CCl2O(g) -219.1 -204.9 283.5
CCl4(g) -95.7 -53.6 309.9
CCl4(l) -128.2 -62.6 216.2
CF4(g) -933.6 -888.3 261.6
CS2(g) 116.7 67.1 237.8 45.4
CS2(l) 89 64.6 151.3 76.4
CO(g) -110.5 -137.2 197.7 29.1
CO2(g) -393.5 -394.4 213.8 37.1
Ca(g) 177.8 144 154.9 20.8
Ca(s) 0 0 41.6 25.9
Ca(OH)2(s) -985.2 -897.5 83.4 87.5
CaBr2(s) -682.8 -663.6 130
CaCl2(s) -795.4 -748.8 108.4 72.9
CaCN(s) -184.5
CaCO3(s, aragonite) -1207.8 -1128.2 88 82.3
CaCO3(s, calcite) -1207.6 -1129.1 91.7 83.5
CaF2(s) -1228.0 -1175.6 68.5 67.0
CaH2(s) -181.5 -142.5 41.4 41.0
CaI2(s) -533.5 -528.9 142
CaO(s) -634.9 -603.3 38.1 42.0
CaSO4(s) -1434.5 -1322.0 106.5 99.7
Cd(g) 111.8 167.7 20.8
Cd(s) 0 0 51.8 26.0
CdBr2(s) -316.2 -296.3 137.2 76.7
CdCl2(s) -391.5 -343.9 115.3 74.7
CdCO3(s) -750.6 -669.4 92.5
CdF2(s) -700.4 -647.7 77.4
CdS(s) -161.9 -156.5 64.9
CdSO4(s) -933.3 -822.7 123.0 99.6
Cl-(aq) -167.1 -131.2 56.6
Cl(g) 121.3 105.3 165.2 21.8
Cl2(g) 0 0 223.1 33.9
ClF(g) -50.3 -51.8 217.9 32.1
ClF3(g) -163.2 -123.0 281.6 63.9
ClO2(g) 89.1 105 263.7 46.0
Cl2O(g) 80.3 97.9 266.2 45.4
Co(g) 424.7 380.3 179.5 23.0
Co(s) 0 0 30 24.8
CoCl2(s) -312.5 -269.8 109.2 78.5
Cr(g) 396.6 351.8 174.5 20.8
Cr(s) 0 0 23.8 23.4
Cr2O3(s) -1139.7 -1058.1 81.2 118.7
CrCl2(s) -395.4 -356 115.3 71.2
CrCl3(s) -556.5 -486.1 123 91.8
CrO2(g) -598
CrO3(g) -292.9 266.2 56.0
Cs(g) 76.5 49.6 175.6 20.8
Cs(s) 0 0 85.2 32.2
CsCl(s) -443.0 -414.5 101.2 52.5
Cu(g) 337.4 297.7 166.4 20.8
Cu(s) 0 0 33.2 24.2
Cu2O(s) -168.6 -146.0 93.1 63.6
CuO(s) -157.3 -129.7 42.6
Cu2S(s) -79.5 -86.2 120.9 76.3
CuS(s) -53.1 -53.6 66.5 47.8
CuSO4(s) -771.4 -662.2 109.2
CuBr(s) -104.6 -100.8 96.1 54.7
CuBr2(s) -141.8
CuCl(s) -137.2 -119.9 86.2 48.5
CuCl2(s) -220.1 -175.7 108.1 71.9
CuCN(s) 96.2 111.3 84.5
F-(aq) -335.4 -278.8 -13.8
F(g) 79.4 62.3 158.8 22.7
F2(g) 0 0 202.8 32.3
F2O(g) 24.5 41.8 247.5 43.3
FO(g) 109 105.3 216.4 32.0
FB(g) -122.2 -149.8 200.5 58.6
Fe(g) 416.3 370.7 180.5 25.7
Fe(s) 0 0 27.3 25.1
FeO(s) -272.0 -251.4 60.7
Fe2+(aq) -89.1 -78.9 -137.7
Fe2O3(s) -824.2 -742.2 87.4 103.9
Fe3+(aq) -48.5 -4.7 -315.9
Fe3O4(s) -1118.4 -1015.4 146.4 143.4
FeCO3(s) -740.6 -666.7 92.9 82.1
FeS2(s) -178.2 -166.9 52.9 62.2
FeCl2(s) -341.8 -302.3 118 75.7
FeCl3(s) -399.5 -334.0 142.3 96.7
FeBr2(s) -249.8 -238.1 140.6
FeBr3(s) -268.2
Fe3C(s) 25.1 20.1 104.6 105.9
H(g) 218.0 203.3 114.7 20.8
H+(aq) 0 0 0
H2(g) 0 0 130.7 28.8
H2O(g) -241.8 -228.6 188.8 33.6
H2O(l) -285.8 -237.1 70.0 75.3
H2O2(g) -136.3 -105.6 232.7 43.1
H2O2(l) -187.8 -120.4 109.6 89.1
H2S(g) -20.6 -33.4 205.8 34.2
H2Se(g) 29.7 15.9 219 34.7
H2SO4(aq) -909.3 -744.5 20.1
H2SO4(l) -814.0 -690.0 156.9 138.9
H3PO4(l) -1271.7 -1123.6 150.8 145.0
H3PO4(s) -1284.4 -1124.3 110.5 106.1
HBr(aq) -121.6 -104.0 82.4
HBr(g) -36.3 -53.4 198.7 29.1
HCl(aq) -167.2 -131.2 56.5
HCl(g) -92.3 -95.3 186.9 29.1
HCN(g) 135.1 124.7 201.8 35.9
HCN(l) 108.9 125 112.8 70.6
HF(aq) -332.6 -278.8 -13.8
HF(g) -273.3 -275.4 173.8
HI(aq) -55.2 -51.6 111.3
HI(g) 26.5 1.7 206.6 29.2
HNO2(g) -79.5 -46.0 254.1
HNO3(aq) -207.4 -111.3 146.4
HNO3(g) -133.9 -73.5 266.9 54.1
HNO3(l) -174.1 -80.7 155.6 109.9
He(g) 0 0 126.2 20.8
Hg(g) 61.4 31.8 175
Hg(l) 0 0 75.9 28.0
Hg2(g) 108.8 68.2 288.1
HgO(s) -90.8 -58.5 70.3 44.1
HgS(s, red) -58.2 -50.6 82.4 48.4
Hg2SO4(s) -743.1 -625.8 200.7 132.0
HgSO4(s) -707.5
Hg2Cl2(s) -265.4 -210.7 191.6 191.6
HgCl2(s) -224.3 -178.6 146.0 146.0
Hg2Br2(s) -206.9 -181.1 218.0 218.0
HgBr2(s) -170.7 -153.1 172.0 172.0
Hg2I2(s) -121.3 -111 233.5 233.5
HgI2(s) -105.4 -101.7 180.0 180.0
I-(aq) -56.8 -51.6 106.5
I(g) 106.8 70.2 180.8 20.8
I2(g) 62.4 19.3 260.7 36.9
I2(s) 0 0 116.1 54.4
HIO3(s) -230.1
IBr(g) 40.8 3.7 258.8 36.4
ICl(g) 17.8 -5.5 247.6 35.6
IF(g) -95.7 -118.5 236.2 33.4
K(g) 89.0 60.5 160.3 20.8
K(s) 0 0 64.7 29.6
K2CO3(s) -1151.0 -1063.5 155.5 114.4
K2O(s) -361.5 -322.1 94.1
K2O2(s) -494.1 -425.1 102.1
K2SO4(s) -1437.8 -1321.4 175.6 131.5
KBr(s) -393.8 -380.7 95.9 52.3
KCl(s) -436.5 -408.5 82.6 51.3
KF(s) -567.3 -537.8 66.6 49.0
KI(s) -327.9 -324.9 106.3 52.9
KClO3(s) -397.7 -296.3 143.1 100.3
KMnO4(s) -837.2 -737.6 171.7 117.6
KNO2(s) -369.8 -306.6 152.1 107.4
KNO3(s) -494.6 -394.9 133.1 96.4
KSCN(s) -200.2 -178.3 124.3 88.5
Kr(g) 0 0 164.1 20.8
Li(g) 159.3 126.6 138.8 20.8
Li(s) 0 0 29.1 24.9
Li+(aq) -278.5 -293.3 12.4
Li2O(s) -597.9 -561.2 37.6 54.1
LiOH(s) -487.5 -441.5 42.8 49.6
LiNO3(s) -483.1 -381.1 90.0
LiBr(s) -351.2 -342 74.3
LiCl(s) -408.6 -384.4 59.3 48.0
LiF(s) -616 -587.7 35.7 41.6
LiI(s) -270.4 -270.3 86.8 51.0
Mg(g) 147.1 112.5 148.6 20.8
Mg(s) 0 0 32.7 24.9
MgO(s) -601.6 -569.3 27.0 37.2
Mg(OH)2(s) -924.5 -833.5 63.2 77.0
MgS(s) -346.0 -341.8 50.3 45.6
MgSO4(s) -1284.9 -1170.6 91.6 96.5
MgBr2(s) -524.3 -503.8 117.2
MgCl2(s) -641.3 -591.8 89.6 71.4
MgF2(s) -1124.2 -1071.1 57.2 61.6
Mn(g) 280.7 238.5 173.7 20.8
Mn(s) 0 0 32 26.3
MnO(s) -385.2 -362.9 59.7 45.4
MnO2(s) -520.0 -465.1 53.1 54.1
MnO4-(aq) -541.4 -447.2 191.2
MnBr2(s) -384.9
MnCl2(s) -481.3 -440.5 118.2 72.9
Mo(g) 658.1 612.5 182 20.8
Mo(s) 0 0 28.7 24.1
MoO2(s) -588.9 -533.0 46.3 56.0
MoO3(s) -745.1 -668.0 77.7 75.0
MoS2(s) -235.1 -225.9 62.6 63.6
MoS3(s) -364 -354 119
N(g) 472.7 455.5 153.3 20.8
N2(g) 0 0 191.6 29.1
NF3(g) -132.1 -90.6 260.8 53.4
NH3(g) -45.9 -16.4 192.8 35.1
NH4+(aq) -133.3 -79.3 111.2
NH4Cl(s) -314.4 -202.9 94.6 84.1
NH4NO3(s) -365.6 -183.9 151.1 139.3
NH4OH(l) -361.2 -254.0 165.6 154.9
(NH4)2SO4(s) -1180.9 -901.7 220.1 187.5
N2H4(g) 95.4 159.4 238.5
N2H4(l) 50.6 149.3 121.2
NO2(g) 33.2 51.3 240.1 37.2
N2O(g) 81.6 103.7 220 38.6
NO(g) 91.3 87.6 210.8
N2O4(g) 11.1 99.8 304.4 79.2
N2O4(l) -19.5 97.5 209.2 142.7
Na(g) 107.5 77 153.7 20.8
Na(s) 0 0 51.3 28.2
Na+(aq) -240.2 -261.9 58.5
Na2CO3(s) -1130.7 -1044.4 135 112.3
Na2O(s) -414.2 -375.5 75.1 69.1
Na2O2(s) -510.9 -447.7 95 89.2
Na2SO4(s) -1387.1 -1270.2 149.6 128.2
NaBr(aq) -361.7 -365.8 141.4
NaBr(g) -143.1 -177.1 241.2 36.3
NaBr(s) -361.1 -349.0 86.8 51.4
NaCl(aq) -407.3 -393.1 115.5
NaCl(s) -411.2 -384.1 72.1 50.5
NaCN(s) -87.5 -76.4 115.6 70.4
NaF(aq) -572.8 -540.7 45.2
NaF(s) -576.6 -546.3 51.1 46.9
NaN3(s) 21.7 93.8 96.9 76.6
NaNO3(aq) -447.5 -373.2 205.4
NaNO3(s) -467.9 -367.0 116.5 92.9
NaO2(s) -260.2 -218.4 115.9 72.1
NaOH(s) -425.8 -379.7 64.4 59.5
NaH(s) -56.3 -33.6 40 36.4
Ne(g) 0 0 146.3 20.8
Ni(g) 429.7 384.5 182.2 23.4
Ni(s) 0 0 29.9 26.1
Ni2O3(s) -489.5
Ni(OH)2(s) -529.7 -447.2 88
NiBr2(s) -212.1
NiCl2(s) -305.3 -259.0 97.7 71.7
NiF2(s) -651.4 -604.1 73.6 64.1
O(g) 249.2 231.7 161.1 21.9
O2(g) 0 0 205.2 29.4
O3(g) 142.7 163.2 238.9 39.2
OH-(aq) -230.0 -157.2 -10.9
Os(g) 791 745 192.6 20.8
Os(s) 0 0 32.6 24.7
OsO4(g) -337.2 -292.8 293.8 74.1
OsO4(s) -394.1 -304.9 143.9
P(g, white) 316.5 280.1 163.2 20.8
P(s, black) -39.3
P(s, red) -17.6 -12.5 22.8 21.2
P(s, white) 0 0 41.1 23.8
P2(g) 144.0 103.5 218.1
P4(g) 58.9 24.4 280.0
PCl3(g) -287.0 -267.8 311.8 71.8
PCl3(l) -319.7 -272.3 217.1
PCl5(g) -374.9 -305.0 364.6 112.8
PH3(g) 5.4 13.5 210.2 37.1
POCl3(g) -558.5 -512.9 325.5
POCl3(l) -597.1 -520.8 222.5
Pb(g) 195.2 162.2 175.4 20.8
Pb(s) 0 0 64.8 26.8
PbCl2(s) -359.4 -314.1 136
PbCO3(s) -699.1 -625.5 131 87.4
PbO(s, red or litharge) -219.0 -188.9 66.5 45.8
PbO(s, yellow or massicot) -217.3 -187.9 68.7 45.8
PbO2(s) -277.4 -217.3 68.6 64.6
Pb(NO3)2(aq) -416.3 -246.9 303.3
Pb(NO3)2(s) -451.9
PbS(s) -100.4 -98.7 91.2 49.5
PbSO4(s) -920.0 -813.0 148.5 103.2
Rb(g) 80.9 53.1 170.1 20.8
Rb(s) 0 0 76.8 31.1
RbCl(s) -435.4 -407.8 95.9 52.4
S(g, rhombic) 277.2 236.7 167.8 23.7
S(s, rhombic) 0 0 32.1 22.6
SO2(g) -296.8 -300.1 248.2 39.9
SO3(g) -395.7 -371.1 256.8 50.7
SO42-(aq) -909.3 -744.5 18.5
SOCl2(g) -212.5 -198.3 309.8
Se(g, gray) 227.1 187 176.7
Se(s, gray) 0 0 42.4 25.4
Si(g) 450 405.5 168.0 22.3
Si(s) 0 0 18.8 20.0
SiC(s, cubic) -65.3 -62.8 16.6 26.9
SiC(s, hexagonal) -62.8 -60.2 16.5 26.7
SiCl4(g) -657.0 -617.0 330.7
SiCl4(l) -687.0 -619.8 239.7
SiH4(g) 34.3 56.9 204.6 42.8
Sn(g, white) 301 266.2 168.5 21.3
Sn(s, gray) -2.1 0.1 44.1 25.8
Sn(s, white) 0 0 51.2 27.0
SnCl4(g) -471.5 -432.2 365.8 98.3
SnCl4(l) -511.3 -440.1 258.6 165.3
SnO2(s) -557.6 -515.8 49 52.6
Ti(g) 473 428.4 180.3 24.4
Ti(s) 0 0 30.7 25.1
TiCl2(s) -513.8 -464.4 87.4 69.8
TiCl3(s) -720.9 -653.5 139.7 97.2
TiCl4(g) -763 -726.3 353 95.4
TiCl4(l) -804.2 -737.2 252.3 145.2
TiO2(s) -944.0 -888.8 50.6 55.0
U(g) 533 488.4 199.8 23.7
U(s) 0 0 50.2 27.7
UF4(g) -1598.7 -1572.7 368 91.2
UF4(s) -1914.2 -1823.3 151.7 116.0
UF6(g) -2147.4 -2063.7 377.9 129.6
UF6(s) -2197.0 -2068.5 227.6 166.8
UO2(g) -465.7 -471.5 274.6 51.4
UO2(s) -1085.0 -1031.8 77.0 63.6
V(g) 514.2 754.4 182.3 26.0
V(s) 0 0 28.9 24.9
V2O5(s) -1550.6 -1419.5 131.0 127.7
VCl3(s) -580.7 -511.2 131.0 93.2
VCl4(g) -525.5 -492.0 362.4 96.2
VCl4(l) -569.4 -503.7 255.0
Xe(g) 0 0 169.7 20.8
Zn(g) 130.4 94.8 161.0 20.8
Zn(s) 0 0 41.6 25.4
ZnBr2(s) -328.7 -312.1 138.5
ZnCl2(s) -415.1 -369.4 111.5 71.3
ZnF2(s) -764.4 -713.3 73.7 65.7
ZnI2(s) -208.0 -209.0 161.1
Zn(NO3)2(s) -483.7
ZnS(s, sphalerite) -206.0 -201.3 57.7 46.0
ZnSO4(s) -982.8 -871.5 110.5 99.2
Zr(g) 608.8 566.5 181.4 26.7
Zr(s) 0 0 39 25.4
ZrCl2(s) -502.0 -386 110
ZrCl4(s) -980.5 -889.9 181.6 119.8

For conversion of units, use the Specific heat online unit converter.

See also tabulated values of specific heat capacity of gases, food and foodstuff, metals and semimetals, common liquids and fluids, common solids, and other common substances as well as values of molar heat capacity of common organic substances.

The specific heat capacity can be calculated from the molar heat capacity, and vise versa:

cp = Cp/ M and

Cp = cp . M

where

cp = specific heat capacity

Cp = molar heat capacity

M = molar weight of the actual substance (g/mol).