cheme140-fall05-mt1-Radke-soln - Chemical Engineering 140...

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Chemical Engineering 140 September 26, 2005 Midterm #1 Solution (total pts: 185) (120) 1. (40) i. Use transient species mass balance on salt in upper chamber CV = Upper chamber volume = V Transient mass balance for species i = salt . No reaction, no outlet streams ) , , out i in i i m m dt dm + - = i in i i i M n dt M n d , ) ( = Constant species molecular weight M i allows us to reduce mass balance to mole balance in i i V i n dt V C d dV r C dt d , ) ( ) ( = = (Well mixed tank C i is indep. of position) (*) But, rate of moles in varies with the concentration difference across the SCL: ( 29 ) ( ˆ , t C c L PA A N n i o i in i - = = (Relationship for flux N is given in part (i).) (**) Combining (*) and (**), we obtain ( 29 ) ( ) ( t C c L PA dt dC V C dt V C d i o i i i - = + = (V const) Receptor cell SCL Donor cell Conductivity probe V c o N salt L A C salt (t) Given in problem statement: A ≡ Area of membrane (SCL) V ≡ Volume of receptor cell, CONSTANT L ≡ Thickness of membrane (SCL) c o ≡ Concentration of salt in donor cell, CONSTANT Both tanks are WELL MIXED C salt
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This note was uploaded on 02/18/2010 for the course CHEME 120A taught by Professor Gilman during the Spring '10 term at University of California, Berkeley.

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cheme140-fall05-mt1-Radke-soln - Chemical Engineering 140...

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