Question

White phosphorus (P4) was used for a long time in military incendiary bombs and ordnances. White phosphorus reacts with oxygen in the air and burns at very high temperatures, so it sets things on fire. Calculate the change in enthalpy resulting from a 25.0 pound white phosphorus artillery shell reacting with the oxygen in the atmosphere to form P4O10 (s). The enthalpy of formation can be found in an appendix of your text book. Give the answer in MJ (mega-joules).

Answer 1

Works the same way as dG but this is dH.
Write ad balance the equation.
dHrxn = (n*dHo products) - (n*dHo reactants). Of course you will need ton convert 25 lbs to grams.