Vapour pressure?

[limbeh]

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

[Crna Legija]

vapour pressure of what?

[limbeh]

They gave us 96% ethanol.

Googling around to find out the total vapour pressure is giving me nothing though.

[acs2997]

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.

[jimmy101]

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.