# Gchem

Discussion in 'DAT Discussions' started by Lonely Sol, Apr 26, 2007.

1. ### Lonely Sol cowgoesmoo fan!

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A sample of air held in a graduated cylinder over water has a volumne of 88.3ml at a temperature of 18.5 degree C. and a pressure of 741nm. What would the volume of the air be if it were dry and at the same temperature and pressure?

3. ### Nasem

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This is classic PV = nRT,
Since n, R, and T are constancts in this, we leave them out and put

PiVi = PfVf

You know your initial pressure and volume,
you also know your final pressure (since it says constant), just need to solve for Vf

4. ### orthdent786 Junior Member

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if thats the case then Vi=Vf b/c the pressures just cancel out, i'm not sure if that is the equation we are supposed to use? maybe someone else can help?

5. ### doc toothache

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The (vapor) pressure contributed by water at 18.5 degree C is about 20mm. It needs to be subtracted from 741mm then use P1V1=P2V2.

6. ### infernobutterfl Pyro user

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we are supposed to know the vapor pressure of water??

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