Question

5. a) On a plant floor, ethanol has spilt and forms a layer with 1 mm thickness. If we assume that the rate of evaporation of the ethanol is controlled by the rate of diffusion of ethanol through a stagnant film of air with 5 mm thickness, calculate the time needed for the evaporation of all the ethanol. Derive any equations you use The temperature is 20 °C and the pressure is 760 mmHg. 115] b) State all the assumptions you use in the above problem. 15] Ethanol properties: Density 795 kg m3 Molecular weight 46 kg kmol Vapour pressure (at 20 °C) 45 mmHg Diffusion coefficient of ethanol n air 1337 x 10 m s -I 5 2-I

Answer 1

o-3 0.6も = 0111224-tival 2 る,

95 X y 6 melis tine