How is saturation pressure different than vapor pressure?

In summary, the vapor pressure of a substance is the pressure at which it evaporates or sublimates at a given temperature, calculated using the Antoine Equation and measured at the interface with the atmosphere or anywhere in the system if it is at equilibrium. Saturation pressure, on the other hand, assumes the substance has fully vaporized and can be measured at any gaseous part of the system. The main difference between the two is that vapor pressure assumes equilibrium at the surface, while saturation pressure does not take into account the rest of the system.
  • #1
pa5tabear
175
0
I think I understand, but I want to make sure.

The vapor pressure of a substance is the pressure of the substance evaporating/sublimating at a given temperature and can be calculated using the Antoine Equation. This must be measured at the interface of the substance and atmosphere, or if the system is at equilibrium, it could be measured anywhere in the system.

The saturation pressure assumes that the substance has fully vaporized to its equilibrium point. It could be measured at any gaseous part of the system.

They are almost the same, right? The difference is just whether the system is at equilibrium?
 
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  • #2
If I understand your question correctly - yes. We just assume pressure has its maximum possible value at the interface, no matter what is going on in other parts of the system. This is equivalent of assuming there is an equilibrium on the surface.
 

1. What is saturation pressure and vapor pressure?

Saturation pressure is the pressure at which a substance changes from liquid to gas at a given temperature. Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid or solid phase at a given temperature.

2. How are saturation pressure and vapor pressure related?

They are both properties of a substance and are related by the Clausius-Clapeyron equation, which describes the relationship between pressure, temperature, and the phase change of a substance.

3. Is saturation pressure always higher than vapor pressure?

No, saturation pressure can be equal to or lower than vapor pressure, depending on the temperature and properties of the substance.

4. How do saturation pressure and vapor pressure affect phase changes?

When the vapor pressure of a substance is equal to the surrounding atmospheric pressure, it will reach saturation pressure and undergo a phase change from liquid to gas. If the vapor pressure is lower than the surrounding atmospheric pressure, the substance will remain in its liquid state.

5. Can saturation pressure and vapor pressure change with temperature?

Yes, both saturation pressure and vapor pressure are affected by temperature. As temperature increases, so does vapor pressure. Saturation pressure also increases with temperature, but at a slower rate due to the substance's properties.

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