To calculate the amount of heat released when 2.5 moles of propane is completely burned, we can use the standard enthalpy of combustion of propane, which is -2220 kJ/mol.Heat released = moles of propane standard enthalpy of combustion Heat released = 2.5 moles -2220 kJ/mol Heat released = -5550 kJThe negative sign indicates that the reaction is exothermic, meaning heat is released. Therefore, 5550 kJ of heat is released when 2.5 moles of propane is completely burned in oxygen gas.