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Heats of Formation |
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Thermochemistry Table for Common Compounds
The molar heat 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.
| Compound |
ΔHf (kJ/mol) |
Compound |
ΔHf (kJ/mol) |
| AgBr(s) |
-99.5 |
C2H2(g) |
+226.7 |
| AgCl(s) |
-127.0 |
C2H4(g) |
+52.3 |
| AgI(s) |
-62.4 |
C2H6(g) |
-84.7 |
| Ag2O(s) |
-30.6 |
C3H8(g) |
-103.8 |
| Ag2S(s) |
-31.8 |
n-C4H10(g) |
-124.7 |
| Al2O3(s) |
-1669.8 |
n-C5H12(l) |
-173.1 |
| BaCl2(s) |
-860.1 |
C2H5OH(l) |
-277.6 |
| BaCO3(s) |
-1218.8 |
CoO(s) |
-239.3 |
| BaO(s) |
-558.1 |
Cr2O3(s) |
-1128.4 |
| BaSO4(s) |
-1465.2 |
CuO(s) |
-155.2 |
| CaCl2(s) |
-795.0 |
Cu2O(s) |
-166.7 |
| CaCO3 |
-1207.0 |
CuS(s) |
-48.5 |
| CaO(s) |
-635.5 |
CuSO4(s) |
-769.9 |
| Ca(OH)2(s) |
-986.6 |
Fe2O3(s) |
-822.2 |
| CaSO4(s) |
-1432.7 |
Fe3O4(s) |
-1120.9 |
| CCl4(l) |
-139.5 |
HBr(g) |
-36.2 |
| CH4(g) |
-74.8 |
HCl(g) |
-92.3 |
| CHCl3(l) |
-131.8 |
HF(g) |
-268.6 |
| CH3OH(l) |
-238.6 |
HI(g) |
+25.9 |
| CO(g) |
-110.5 |
HNO3(l) |
-173.2 |
| CO2(g) |
-393.5 |
H2O(g) |
-241.8 |
| H2O(l) |
-285.8 |
NH4Cl(s) |
-315.4 |
| H2O2(l) |
-187.6 |
NH4NO3(s) |
-365.1 |
| H2S(g) |
-20.1 |
NO(g) |
+90.4 |
| H2SO4(l) |
-811.3 |
NO2(g) |
+33.9 |
| HgO(s) |
-90.7 |
NiO(s) |
-244.3 |
| HgS(s) |
-58.2 |
PbBr2(s) |
-277.0 |
| KBr(s) |
-392.2 |
PbCl2(s) |
-359.2 |
| KCl(s) |
-435.9 |
PbO(s) |
-217.9 |
| KClO3(s) |
-391.4 |
PbO2(s) |
-276.6 |
| KF(s) |
-562.6 |
Pb3O4(s) |
-734.7 |
| MgCl2(s) |
-641.8 |
PCl3(g) |
-306.4 |
| MgCO3(s) |
-1113 |
PCl5(g) |
-398.9 |
| MgO(s) |
-601.8 |
SiO2(s) |
-859.4 |
| Mg(OH)2(s) |
-924.7 |
SnCl2(s) |
-349.8 |
| MgSO4(s) |
-1278.2 |
SnCl4(l) |
-545.2 |
| MnO(s) |
-384.9 |
SnO(s) |
-286.2 |
| MnO2(s) |
-519.7 |
SnO2(s) |
-580.7 |
| NaCl(s) |
-411.0 |
SO2(g) |
-296.1 |
| NaF(s) |
-569.0 |
So3(g) |
-395.2 |
| NaOH(s) |
-426.7 |
ZnO(s) |
-348.0 |
| NH3(g) |
-46.2 |
ZnS(s) |
-202.9 |
Reference: Masterton, Slowinski, Stanitski, Chemical Principles, CBS College Publishing, 1983.
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