Looked up some properties of active metals and their oxides.
Al2O3 enthalpy of formation -1675 kJ/mol, making -558 kJ/mol O (linked Wikipedia to Zumdahl), Al boils at 2470 degrees
BeO enthalpy -599 kJ/mol, Be boils at 2470 degrees
MgO enthalpy -602 kJ/mol, Mg boils at 1090 degrees
CaO enthalpy -635 kJ/mol, Ca boils at 1484 degrees
SrO enthalpy -592 kJ/mol, Sr boils at 1377 degrees
BaO enthalpy -582 kJ/mol, Ba boils at 1845 degrees
Li2O enthalpy -596 kJ/mol, Li boils at 1330 degrees
Na2O enthalpy -416 kJ/mol (sic!, also Zumdahl), Na boils at 883 degrees
K2O enthalpy -363 kJ/mol, K boils at 759 degrees
Note:
Alkali metals other than Li have only small affinity for oxygen. Heating metal oxides with metallic Na or K is likely to not work with moderately
active metals!
The most active metal turns out to be Ca. And Ca has fairly high boiling point - higher than Mg.
While Ca is fairly reactive in wet air, not so much as Na. So, how useful are thermites based on metallic Ca? 12thealchemist - 23-12-2018 at 01:27
I think that depends on how easy it is to obtain, store, and use the finely divided metal. It sounds as though you'd be done for in anything other
than dry air conditions.BOBardment - 28-12-2018 at 10:56
One interesting thing I heard about iron thermites.
Fe2O4 actually release more heat than Fe2O3, but Fe2O3 burns longer.
Honestly, even the regular old plain and boring iron thermite is powerful enough as it is. It's more about how to use it to get the maximum effect out
of it.BOBardment - 1-1-2019 at 15:35
