To calculate the amount of heat released, we first need to determine the number of moles of ethanol in 2.5 grams.Number of moles = mass / molar massNumber of moles = 2.5 g / 46.07 g/mol = 0.0542 molNow, we can use the heat of combustion to find the amount of heat released.Heat released = number of moles heat of combustionHeat released = 0.0542 mol -1371 kJ/mol = -74.3 kJThe negative sign indicates that the heat is released exothermic reaction . Therefore, the amount of heat released when 2.5 grams of ethanol burns completely in excess oxygen is 74.3 kJ.