Vapour pressure?

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limbeh
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Mon Jul 16, 2012 12:33 am

Hey guys,

I got a problem here. My freshman uni course is making us do a problem of modelling a combustion cannon for thermodynamics.

I can get the vapour pressure using Antoine's equation, but I can't google and find out whether the total pressure is the vapour pressure + atmospheric pressure or what.

Thanks!

Limbeh
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Crna Legija
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Mon Jul 16, 2012 1:12 am

vapour pressure of what?
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limbeh
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Mon Jul 16, 2012 8:37 am

They gave us 96% ethanol.

Googling around to find out the total vapour pressure is giving me nothing though.
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acs2997
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Mon Jul 16, 2012 8:40 am

I believe the atmosperic pressure is often disregarded, but if you really want to find out the total pressure, I think you just need to add 14.7 psi (im not sure what that is in other measurements) to your vapor pressure. its quite simple.
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Mon Jul 16, 2012 11:13 am

Open of closed container?

In an open container the pressure is just atmospheric, regardless of the presence of a volatile liquid.

In a closed container, and assuming it was closed before an appreciable amount of the liquid had vaporized, the pressure is atmospheric plus the vapor pressure of the liquid.
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