Standard Gibbs free energy of formation explained

The standard Gibbs free energy of formation (G_f°) of a compound is the change of Gibbs free energy that accompanies the formation of 1 mole of a substance in its standard state from its constituent elements in their standard states (the most stable form of the element at 1 bar of pressure and the specified temperature, usually 298.15 K or 25 °C).

The table below lists the standard Gibbs function of formation for several elements and chemical compounds and is taken from Lange's Handbook of Chemistry. Note that all values are in kJ/mol. Far more extensive tables can be found in the CRC Handbook of Chemistry and Physics and the NIST JANAF tables.^[1] The NIST Chemistry WebBook (see link below) is an online resource that contains standard enthalpy of formation for various compounds along with the standard absolute entropy for these compounds from which the standard Gibbs free energy of formation can be calculated.

Species	Phase (matter)	Chemical formula	ΔGf° (kJ/mol)
Aluminum
Aluminum	Solid	Al	0
Aluminum chloride	Solid	AlCl3	−628.9
Aluminum oxide	Solid	Al2O3	−1582.3
Barium
Barium	Solid	Ba	0
Barium chloride	Solid	BaCl2	−806.7
Barium carbonate	Solid	BaCO3	−1134.4
Barium oxide	Solid	BaO	−520.4
Barium sulfate	Solid	BaSO4	−1362.2
Beryllium
Beryllium	Solid	Be	0
Beryllium hydroxide	Solid	Be(OH)2	−815.0
Boron
Boron trichloride	Solid	BCl3	−388.7
Bromine
Bromine	Liquid	Br2	0
Bromine trifluoride	Gas	BrF3	−229.4
Hydrobromic acid	Gas	HBr	−53.4
Calcium
Calcium	Solid	Ca	0
Calcium carbide	Solid	CaC2	−64.9
Calcium carbonate (Calcite)	Solid	CaCO3	−1129.1
Calcium chloride	Solid	CaCl2	−748.8
Calcium chloride	Aqueous	CaCl2	−816.05
Calcium hydride	Solid	CaH2	−142.5
Calcium hydroxide	Solid	Ca(OH)2	−897.5
Calcium oxide	Solid	CaO	−603.3
Calcium sulfate	Solid	CaSO4	−1309.1
Calcium sulfide	Solid	CaS	−477.4
Carbon
Carbon (graphite)	Solid	C	0
Carbon (diamond)	Solid	C	2.900
Carbon dioxide	Gas	CO2	−394.39
Carbonic acid	Aqueous	H2CO3	−623.1
Bicarbonate	Aqueous	HCO3^−	−586.85
Carbonate ion	Aqueous	CO3^2−	−527.8
Carbon disulfide	Gas	CS2	67.1
Carbon monoxide	Gas	CO	−137.16
Glucose	Solid	C6H12O6	−910.56
Ethanol	Liquid	C2H5OH	−174.8
Carbonyl chloride (phosgene)	Gas	COCl2	−204.9
Caesium
Caesium	Solid	Cs	0
Caesium chloride	Solid	CsCl	−414.4
Chlorine
Chlorine	Gas	Cl2	0
Chromium
Chromium	Solid	Cr	0
Copper
Copper	Solid	Cu	0
Copper(I) sulfide	Solid	Cu2S	−86.2
Fluorine
Fluorine	Gas	F2	0
Hydrogen
Hydrogen	Gas	H2	0
Water	Liquid	H2O	−237.14
Water	Gas	H2O	−228.61
Hydrogen peroxide	Liquid	H2O2	−120.42
Hydrogen cyanide	Gas	HCN	+124.7
Hydrogen iodide	Gas	HI	+1.3
Hydrogen fluoride	Gas	HF	−275.4
Hydrogen chloride	Gas	HCl	−95.30
Iodine
Iodine	Solid	I2	0
Iodine	Gas	I2	19.37
Iron
Lead
Lithium
Magnesium
Magnesium carbonate	Solid	MgCO3	−1012.1
Magnesium chloride	Solid	MgCl2	−591.8
Magnesium hydroxide	Solid	Mg(OH)2	−833.7
Magnesium hydroxide	Aqueous	Mg(OH)2	−769.4
Magnesium oxide	Solid	MgO	−596.3
Magnesium sulfate	Solid	MgSO4	−1170.6
Manganese
Manganese(II) oxide	Solid	MnO	−362.9
Manganese(IV) oxide	Solid	MnO2	−465.2
Mercury
Mercury(II) oxide (red)	Solid	HgO	−58.49
Mercury sulfide (red, cinnabar)	Solid	HgS	−50.6
Nickel
Nitrogen
Ammonia	Aqueous	NH3	−26.57
Ammonia	Gas	NH3	−16.4
Ammonium chloride	Solid	NH4Cl	−203.89
Nitrogen dioxide	Gas	NO2	51.3
Nitrogen monoxide	Gas	NO	87.60
Oxygen
Monatomic oxygen	Gas	O	231.7
Dioxygen	Gas	O2	0
Ozone	Gas	O3	163.2
Hydroxide	Aqueous	OH^−	−157.2
Phosphorus
Phosphorus trichloride	Liquid	PCl3	−272.4
Potassium
Potassium bromide	Solid	KBr	−380.7
Potassium chlorate	Solid	KClO3	−296.31
Potassium chloride	Solid	KCl	−408.5
Potassium fluoride	Solid	KF	−537.8
Potassium perchlorate	Solid	KClO4	−303.1
Silicon
Silica (quartz)	Solid	SiO2	−856.4
Silver
Silver bromide	Solid	AgBr	−96.90
Silver chloride	Solid	AgCl	−109.8
Silver iodide	Solid	AgI	−66.19
Silver oxide	Solid	Ag2O	−11.21
Silver sulfide	Solid	Ag2S	−40.67
Sodium
Sodium carbonate	Solid	Na2CO3	−1044.4
Sodium carbonate	Aqueous	Na2CO3	−1051.6
Sodium chloride	Aqueous	NaCl	−393.17
Sodium chloride	Solid	NaCl	−384.1
Sodium fluoride	Solid	NaF	−546.3
Sodium hydroxide	Aqueous	NaOH	−419.2
Sodium hydroxide	Solid	NaOH	−379.4
Sodium nitrate	Aqueous	NaNO3	−373.21
Sodium nitrate	Solid	NaNO3	−367.06
Sulfur
Hydrogen sulfide	Gas	H2S	−33.4
Sulfur dioxide	Gas	SO2	−300.13
Sulfur trioxide	Gas	SO3	−370.4
Sulfuric acid	Liquid	H2SO4	−689.9
Tin
Titanium
Zinc

See also

• Thermochemistry
• Calorimetry

References

1. M. W. Chase, NIST – JANAF Thermochemical Tables, 4th Edition, Journal of Physical and Chemical Reference Data, Monograph 9, 1998.

• Book: Dean. John A.. Lange's Handbook of Chemistry. 15th. 1999. McGraw-Hill. New York. 978-0-07-016384-3.

External links

• NIST Chemistry WebBook