The thermite reaction, in which powdered aluminum reacts with chromium oxide, is highly exothermic. 2al(s)+cr2o3(s)? al2o3(s)+2cr(s) use standard enthalpies of formation to find ? h? rxn for the thermite reaction.

Enthalpies of formation are found in a table, probably in your text book. If not, you can find it on the Internet. You’ll look up the enthalpy for each species in the reaction, and then do

(Sum of products) - (sum of reactants)

Or, more specifically,

(Q of Cr + Q of Al2O3) - (Q Al + Q Cr2O3)

Q is enthalpy, obviously. Hope this helps.