This problem is not
in F&R, 3rd Ed.
As a sophomore majoring in chemical engineering, your chemistry professor in the analytical
laboratory provides you with two carboys: 1) a 10-molar aqueous solution of sodium hydroxide with a
specific gravity of 1.37 (20°/4°), and 2) a 5-molar aqueous solution of sodium hydroxide with a
specific gravity of 1.18 (20°/4°). The professor instructs you to mix 50 mL/min of the first solution
with 4 L/hr of the second solution. He then asks you what is the composition of the final mixture on a
mass and molar basis, and what are the mole fractions of the two incoming streams?
4 L / hr
VA
v90.10.04
=
(50 mL / min) { 60 min / hr x L / 1000 mL } = 3 L / hr
© 2007, Michael E. Hanyak, Jr., All Rights Reserved
Page 5-37
What is Eq. 12? density plus mol. wt.
What is sg? See Page 3-7 in CinChE.
What is Eq. 16? See Page D-2 in CinChE.
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What is Eq. 18?
molar concentration
"gotche" table, p. 3-5
What is Eq. 20?
CinChE, Page D-3
© 2007, Michael E. Hanyak, Jr., All Rights Reserved
Page 5-38
Why NSOLVE here? Eq'ns 4 and 16 are
linear; Eqn's 6, 7, 12 are non-linear. Why?
What's unique here? All
unknowns are for Stream B.
A similar observations is
true for Stream A in Step 6
above.
Click here to view the Excel
"EZ Setup"/Solver solution.
v90.10.04
© 2007, Michael E. Hanyak, Jr., All Rights Reserved
Page 5-39