Do a quick order-of-magnitude estimation. You know (I hope) that 1 mol of gas at 1 atm and 298K occupies 24L, so 1.5 mol would occupy 36L. 0.5L is 1/72 of this volume, so the gas would have to be compressed to 72 atm. So 82 atm doesn't look unreasonable for the pressure at a somewhat higher temperature.