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Topic: Partial molar volume calculation notation  (Read 2804 times)

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Offline Twisted_Nucleics

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Partial molar volume calculation notation
« on: November 20, 2016, 02:28:00 PM »
Hey guys, just a quick question.

I am having a hard time understanding how to finish a calculation because I do not understand some notations and how they are explained in my manual in the equations given. I think I have done everything right up till this point but I just am at a loss.

So this is for a lab report, we did three iterations of salt water in a Weld-type pycnometer, and then had to determine partial molar volume using the weights we got for the pycnometer dry (W0), weighed with DI water (We), and weighed with a NaCl solution we made which was allowed to thermal equilibrate (W).

I have some screenshots, where I am stuck is I cannot figure out how to calculate V1 and V2 because I am confused on the Φo and Vo1 terms. I do not understand what should go here. screenshots are of my excel sheets (only can see the values and sorry its a bit messy :(, but should be enough to tell what I am doing), a screenshot on the calculations needed from the lab manual, and a screenshot of my procedure from my report just in case anyone needs a better clarification on what I did.

I am posting this under pchem for undergraduates (I have not posted here before I do not think, long time lurker tho) so let me know if this is the wrong place...didn't see a pchem hwk section.




Offline Twisted_Nucleics

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Re: Partial molar volume calculation notation
« Reply #1 on: November 20, 2016, 03:45:10 PM »
Well...I see people are viewing, but no one is commenting. Am I missing something that could be useful to solving the problem?

I was looking it over and let's say we ahve an A,B mixture (here salt and water), then,

dV = VAdnA + VBdnB

and I could integrate that from 0 to V and on the other side from 0 to nA and 0 to nB...holding the composition constant and varying nA,nB simultaneously...

I don't know...it doesnt say anything like that in the manual...

Offline mjc123

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Re: Partial molar volume calculation notation
« Reply #2 on: November 21, 2016, 08:20:59 AM »
Well, there are obviously 15 equations before Equation 16; do any of them tell you what φ° and V°1 are?

Offline mjc123

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Re: Partial molar volume calculation notation
« Reply #3 on: November 21, 2016, 11:59:17 AM »
Actually you are told what φ° is, and I strongly suspect that V°1 is just the molar volume of pure solvent.

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