Low-density polyethylene is manufactured from ethylene at medium to high pressure in a radical chain polymerization process. The reaction is exothermic, and on occasion, because of cooling system failure or operator error, there are runaway reactions that raise the pressure and temperature in the reactor to dangerous levels. For safety, there is a relief valve on the reactor that will open when the total pressure reaches 200 bar and discharge the high-pressure ethylene into a holding tank with a volume that is four times larger than that of the reactor, thereby reducing the risk of explosion and discharge into the environment. Assuming the volume occupied by the polymer is very small, that the gas phase is pure ethylene, that in case of a runaway reaction the temperature in the reactor will rise to 400^◦C, and that the holding tank is initially evacuated, what will be the temperature and pressure in the reactor and the holding tank if ethylene can be considered to be an ideal gas with C^∗_P = 73.2 J/(mol K)?