The Question:
A house
with 2,500 ft2 of floor area and 8 ft of a ceiling height needs
to be cooled down from 38.0oC (100.4 oF, very hot)
to 18.0 oC (64.4
oC, comfortable) in a hot Summer
day. How many pounds of Freon (CCl2F2) should be
vaporized in the Air Conditioner in the house ?
Assume that there are not any heat exchange between the house and the atmosphere
except through the air-conditioning system. Heat of vaporization of Freon
is 17.4kJ/mol. Given that specific heat of air = 1.01J/goC,
and density of air = 1.22 g/L).