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[PainRinnegan25]

Hi everyone!

 I need your help in this. It is a problem from our ChE Licensure exam.

 

A 1-m inside diameter spherical tank is 75% full of liquid benzene at 25 ^oC. The cap of the 70-mm diameter opening at the top of the tank was not put in place by mistake causing a benzene vapor loss through the opening. Calculate the rate of loss of benzene by molecular diffusion if the pseudo-state condition is assumed to apply. The temperature is at 25 ^oC and the pressure is 1 atm. The cap is very short and the diffusion through the open space within the vessel needs only to be considered. The vapor pressure of benzene at 25 ^oC is 0.127 bar.

 

 

[breizh]

hi PainRinnegan25,

 

Consider this resource , with examples . This should support your query  ( example 1) .

 

D benzene-air (diffusion coefficient) needs to be calculated or evaluated unless available .

 

http://www.umich.edu...leven/exam4.htm

 

D c6h6/air should be 0.089487 cm2/s

z2-z1 = 0.25 m

y1 =0.127 /1.01325 =0.125339

y2=0 : air (atmosphere)

c= P/(RT)= 0.040873 kmol/m3

 

>>>> Flux of c6h6 /air = C*D* ln ((1-y2)/(1-y1))/(z2-z1) >>>> mass = flux * molecular weight  * section cap

 

# 0.5 kg/day

 

Hope this helps

 

Breizh

Edited by breizh, 29 June 2014 - 04:55 AM.