A service attendant accidently spills 50 litres of gasoline, which quickly spreads over a level surface of area 8 m2 . Estimate the time required for the gasoline to evaporate into the stagnant air...

A service attendant accidently spills 50 litres of gasoline, which quickly spreads
over a level surface of area 8 m2

. Estimate the time required for the gasoline to
evaporate into the stagnant air above the surface of the liquid. The diffusivity
of gasoline in air is 0.65 m2
h
-1
. The air temperature is 298 K. Evaporation may
be assumed to take place through a film of air of 2 m thickness. Vapour pressure
of gasoline at 298 K is 76 mm Hg. The density of gasoline is 720 kg m-3
and
the molecular weight of gasoline is 200. The operation takes place at 1 atm
pressure.