Finding pressure increase required to impart 1J of work

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SUMMARY

The discussion focuses on calculating the pressure increase required to impart 1 Joule of mechanical work when compressing 1 mole of silver and 1 mole of alumina at room temperature. The relevant equations include mechanical work = -PdV and dV = V.alpha.dT - V.beta.dP. For alumina (AL2O3), the molar volume is specified as 25.715 cc/mol, and the compressibility factor (Beta) is 8.0 x 10^-7 (atm)^-1. Participants emphasized the importance of using the correct initial pressure, which is assumed to be 1 atm, and highlighted the need for unit conversions when dealing with molar volumes.

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geobot
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Homework Statement


a) Estimate the pressure increase required to impart 1 J of mechanical work in reversibly compressing 1 mol of silver at room temperature.
b) What pressure rise would be required to impart 1 J of work to 1 mol of alumina at room temperature? For AL2O3 take the molar volume to be 25.715 (cc mol^-1) and Beta= 8.0 x 10^-7 (atm)^-1

Homework Equations


mechanical work = -PdV
dV=V.alpha.dT - V.beta.dP
(maybe: dU = (Cp - PV.alpha)dT + V(P.beta - T.alpha)dP )

The Attempt at a Solution


I have tried and tried to come up with a solution but I just can't figure it out.
See attached jpg.
I would appreciate any thoughts on the question
 

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Your equation in the snapshot involving P's is correct. Just substitute numbers into it. Assume that the starting pressure is 1 atm.

Chet
 
Chestermiller said:
Your equation in the snapshot involving P's is correct. Just substitute numbers into it. Assume that the starting pressure is 1 atm.

Chet

Thank you, can I use that equation for part (b) as well? It does not specify that it is mechanical work or reversible there.
 
geobot said:
Thank you, can I use that equation for part (b) as well? It does not specify that it is mechanical work or reversible there.
Same as (a).
 
Chestermiller said:
Same as (a).
Oh wow, I've been really over thinking this question it seems! thanks again!
 
can I have a solution to this problem?
 
Jairaj Joshi said:
can I have a solution to this problem?
Nope. That's contrary to Physics Forum rules (you should read the guidelines). If you wish to solve this problem and you can't glean enough hints from the current thread's content then you can show your own attempt and present what part you don't understand, or start a new, separate thread and show your attempt there.
 
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Is there any unit conversions that need to be done if my molar volume is given in cc/mol I thought I might need to convert to m^3. The beta value for silver given in my textbook is 9e7 atm^-1, and the molar volume is given as V^S= 10.27 cc/mol, but there is also a V^L=11.54 cc/mol, and I'm not sure of the difference. I know this is an old thread, but any help would be greatly appreciated. I came to the same equation, but cannot get a correct answer.
 

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