HW 3 - p 4.15- VLE, K-values, a and the q-line from VLE Data - 4 pts
Vapor liquid equilibrium data for mixtures of water and isopropanol at 1 atm are given.
(a) Prepare T-x-y and x-y diagrams.
(b) When a solution containing 40 mol% isopropanol is slowly vaporized, what will be the composition of the initial vapor formed?
(c) If this same 40% mixture is heated under equilibrium conditions until 75 mol% has been vaporized, what will be the composition of the liquid and vapor produced?
(a) Prepare T-x-y and x-y diagrams.
(b) When a solution containing 40 mol% isopropanol is slowly vaporized, what will be the composition of the initial vapor formed?
(c) If this same 40% mixture is heated under equilibrium conditions until 75 mol% has been vaporized, what will be the composition of the liquid and vapor produced?
posted by Dr. B at 2:31 PM
7 Comments:
On the homework page, it says "do not do this part". Is this referring to part e?
bighead 1:54 PM:
Yes. Do not do part (e) of this problem. The text does not line up properly on the HW assignment page, so that is not entirely clear.
How are we supposed to find V/F when we don't really know anything except xi? I mean, yi can totally be found using the other diagram, but I still don't understand how to get V/F for the slope of the q-line.
I hear ya. I'm at that same place. Or can we just use the really nice Txy diagram and then just draw a constant temp line to the saturated vapor line? I'm lazy, that's how I want to do it.
uhhhh 5:08 PM:
Let's work on part (b).
It asks for the composition of the initial vapor formed.
So, V = 0 and V/F = 0 and the slope of the q-line is infinity.
The q-line is a vertial line, right ?
Go to your XY diagram and follow this q-line from the 45 up the equilibrium curve and read yi !
billybob 5:12 PM:
Yes, V = 0. See my reply to uhhhh's question for more details.
uhhh 5:25 PM:
Try it my way. You may only get an XY Diagram someday :)
Plus this is only the 1st tiny step towards using the XY Diagram to better understand binary distillation.
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