Heat of Formation Table for Common Compounds

Heat of Formation or Standard Enthalpy of Formation Table

Heat of formation usually is a negative quantity. Remember, the enthalpy of an element in standard state is zero.
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The molar heat of formation (also called standard enthalpy of formation) of a compound (ΔHf) is equal to its enthalpy change (ΔH) when one mole of compound is formed at 25°C and 1 atm from elements in their stable form. This is a table of the heats of formation for a variety of common compounds. As you can see, most heats of formation are negative quantities, which implies that the formation of a compound from its elements usually is an exothermic process.

Points To Remember for Enthalpy Calculations

When using this heat of formation table for enthalpy calculations, remember the following:

  • Calculate the change in enthalpy for a reaction using the heat of formation values of the reactants and products.
  • The enthalpy of an element in its standard state is zero. However, allotropes of an element not in the standard state typically do have enthalpy values.
  • When you reverse the direction of a chemical reaction, the magnitude of ΔH is the same, but the sign changes.
  • When you multiply a balanced equation for a chemical reaction by an integer value, the value of ΔH for that reaction must be multiplied by the integer, too.

Table of Heats of Formation

CompoundΔHf (kJ/mol)CompoundΔHf (kJ/mol)
AgBr(s)-99.5C2H2(g)+226.7
AgCl(s)-127.0C2H4(g)+52.3
AgI(s)-62.4C2H6(g)-84.7
Ag2O(s)-30.6C3H8(g)-103.8
Ag2S(s)-31.8n-C4H10(g)-124.7
Al2O3(s)-1669.8n-C5H12(l)-173.1
BaCl2(s)-860.1C2H5OH(l)-277.6
BaCO3(s)-1218.8CoO(s)-239.3
BaO(s)-558.1Cr2O3(s)-1128.4
BaSO4(s)-1465.2CuO(s)-155.2
CaCl2(s)-795.0Cu2O(s)-166.7
CaCO3-1207.0CuS(s)-48.5
CaO(s)-635.5CuSO4(s)-769.9
Ca(OH)2(s)-986.6Fe2O3(s)-822.2
CaSO4(s)-1432.7Fe3O4(s)-1120.9
CCl4(l)-139.5HBr(g)-36.2
CH4(g)-74.8HCl(g)-92.3
CHCl3(l)-131.8HF(g)-268.6
CH3OH(l)-238.6HI(g)+25.9
CO(g)-110.5HNO3(l)-173.2
CO2(g)-393.5H2O(g)-241.8
H2O(l)-285.8NH4Cl(s)-315.4
H2O2(l)-187.6NH4NO3(s)-365.1
H2S(g)-20.1NO(g)+90.4
H2SO4(l)-811.3NO2(g)+33.9
HgO(s)-90.7NiO(s)-244.3
HgS(s)-58.2PbBr2(s)-277.0
KBr(s)-392.2PbCl2(s)-359.2
KCl(s)-435.9PbO(s)-217.9
KClO3(s)-391.4PbO2(s)-276.6
KF(s)-562.6Pb3O4(s)-734.7
MgCl2(s)-641.8PCl3(g)-306.4
MgCO3(s)-1113PCl5(g)-398.9
MgO(s)-601.8SiO2(s)-859.4
Mg(OH)2(s)-924.7SnCl2(s)-349.8
MgSO4(s)-1278.2SnCl4(l)-545.2
MnO(s)-384.9SnO(s)-286.2
MnO2(s)-519.7SnO2(s)-580.7
NaCl(s)-411.0SO2(g)-296.1
NaF(s)-569.0So3(g)-395.2
NaOH(s)-426.7ZnO(s)-348.0
NH3(g)-46.2ZnS(s)

-202.9

Reference: Masterton, Slowinski, Stanitski, Chemical Principles, CBS College Publishing, 1983.