The molar mass of PCl5 is 208.24 g/mol. So calculating
for the number of moles:
moles PCl5 = 280 / 208.24
moles PCl5 = 1.34 mol
From the equation, 67 kJ of heat is absorbed for every 1
mole hence:
total heat = 67 kJ / mol * 1.34 mol
total heat = 90 kJ
