How ammonium nitrate decomposes?

Ammonium nitrate NH_{4NO3 decomposes in an exothermic reaction and produce two gaseous products from solid reactant:}

Enthalpy change is .
In the presence of carbon (as oxidisable fuel), ethalpy change increases to as in the reaction below with more gaseous products:

The decomposition temperature of pure NH_{4NO3 is 170 °C.}