A hot liquid (c_p = 1000 J/kg∙K) flows at a flow rate of 0.05 kg/s inside a copper pipe with an inner diameter of 45 mm and a wall thickness of 5 mm. At the pipe exit, the liquid temperature decreases by 10°C from its temperature at the inlet. The outer surface of the 5-m-long copper pipe is black oxidized, which subjects the outer surface to radiation heat transfer. The air temperature surrounding the pipe is 10°C. Assuming that the properties of air can be evaluated at 35°C and 1 atm pressure, determine the outer surface temperature of the pipe. Is 35°C an appropriate film temperature for evaluation of the air properties?