What is the phase of a substance?
The uniform state of matter in physical state and chemical composition.
For example:
Solid, liquid, gas
What is a phase transition?
The conversion of one phase to another that occurs spontaneously at certain temperature and pressure.
What is transition temperature? (Ttrs)
The temperature at which two phases are in equilibrium.
What is a phase diagram?
It shows the regions of temperature and pressure at which various phases are thermodynamically stable. Phase boundaries separate those regions, which show the values of temperature and pressure at which two phases can coexist in equilibrium.
What is the boiling temperature?
When the vapor pressure of a liquid equals the atmospheric pressure
The uniform state of matter in physical state and chemical composition.
For example:
Solid, liquid, gas
What is a phase transition?
The conversion of one phase to another that occurs spontaneously at certain temperature and pressure.
What is transition temperature? (Ttrs)
The temperature at which two phases are in equilibrium.
What is a phase diagram?
It shows the regions of temperature and pressure at which various phases are thermodynamically stable. Phase boundaries separate those regions, which show the values of temperature and pressure at which two phases can coexist in equilibrium.
What is the boiling temperature?
When the vapor pressure of a liquid equals the atmospheric pressure
*The vapor pressure and the density rise as temperature raises while the density of the liquid decreases as it expands.
When the density of the vapor equals the density of the liquid, the surface between both phases disappears. The temperature at which that happens is called critical temperature (Tc). The critical pressure (Pc) is when the vapor pressure reaches the critical temperature. When three phases of a substance (such as vapor, liquid and solid) coexist simultaneously in equilibrium, they represent a triple point. It represents the lowest pressure at which a liquid phase of a substance can exist. |
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For curious minds...
This video explains a little bit more about phase diagrams and how the molecules in each phase transition behave. |
Whenever you want to calculate the Enthalpy of Vaporsation from available data of saturation pressure and temperature of compounds you can use the graphic method of Clausius Clapeyron. The next document explains in detail the topic and you will also find a very useful tool to make your life easier!
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Still looking for more examples?
Take some minutes and watch the next video:
Take some minutes and watch the next video:
Last but not least, we will explain what phase rule is and why it is an important number when talking about phase equilibrium.
* The content (infographics and files) uploaded were created by the creators of the page.
Resources:
Atkins, P. and De Paula, J. (2010). Physical chemistry. New York: W.H. Freeman and Co.
Atkins, P. and De Paula, J. (2010). Physical chemistry. New York: W.H. Freeman and Co.