Choice of pressure when using ideal gas equation


by jasoncurious
Tags: ideal gas
jasoncurious
jasoncurious is offline
#1
Dec23-12, 03:41 AM
P: 8
100g of CO are contained in a weighted piston-cylinder device. Initially, the CO is at 1000kPa and 200C. It is then heated until 500C. Determine the final volume of the CO treating it as an ideal gas.

This is what my lecturer gave in his solution:

V2=(mRT2)/P=(0.1kg*0.2968kPa.m3/kg.K*(500+273)K)/1000kPA

My question is: why is the original pressure (1000kPa) been used instead of the final pressure?

Thanks for your help.
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DrDu
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#2
Dec23-12, 05:45 AM
Sci Advisor
P: 3,379
Because initial and final pressure are equal as long as the weight on the cylinder remains the same.
Studiot
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#3
Dec23-12, 10:37 AM
P: 5,462
You can also use Charles Law to calculate the final volume, having calculated the initial volume from the universal gas law.


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