phase boundary

Examples of phase boundary in the following topics:

• Major Features of a Phase Diagram

  • The major features of a phase diagram are phase boundaries and the triple point.
  • Phase boundaries, or lines of equilibrium, are boundaries that indicate the conditions under which two phases of matter can coexist at equilibrium.
  • Along the blue phase boundary, water exists as both a vapor and a liquid.
  • Along the dotted green phase boundary, we see the anomalous behavior of water: it exists as a solid at low-enough temperatures and high-enough pressures.
  • In this phase diagram, which is typical of most substances, the solid lines represent the phase boundaries.

• Interpreting Phase Diagrams

  • The lines that separate these single phase regions are known as phase boundaries.
  • Along the phase boundaries, the matter being evaluated exists simultaneously in equilibrium between the two states that border the phase boundary.
  • When evaluating the phase diagram, it is worth noting that the solid-liquid phase boundary in the phase diagram of most substances has a positive slope.
  • However, the solid-liquid phase boundary for water is anomalous, in that it has a negative slope.
  • The dotted green line refers to the solid-liquid phase boundary for water.

• Supercritical Fluids

  • In addition, there is no surface tension in a supercritical fluid, as there is no liquid to gas phase boundary.
  • In the pressure-temperature phase diagram of CO2, the boiling separates the gas and liquid region and ends in the critical point, where the liquid and gas phases disappear to become a single supercritical phase.
  • At the critical point, (304.1 K and 7.38 MPa) there is no difference in density, and the two phases become one fluid phase.
  • The dry ice melts under high pressure, and forms a liquid and gas phase.
  • When the vessel is heated, the CO2 becomes supercritical -- meaning the liquid and gas phases merge together into a new phase that has properties of a gas, but the density of a liquid.

• Alloys

  • Complete solid solution alloys give single solid phase microstructure.
  • Partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history.
  • Complete solid solution alloys give single solid phase microstructure.
  • Partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history.
  • Alloys can be further classified as homogeneous (consisting of a single phase), heterogeneous (consisting of two or more phases), or intermetallic (where there is no distinct boundary between phases).

• Phase Changes and Energy Conservation

  • A phase of a thermodynamic system and the states of matter have uniform physical properties.
  • The measurement of the external conditions at which the transformation occurs is termed the phase transition.
  • There are well-defined regions on these graphs that correspond to various phases of matter, so PT graphs are called phase diagrams .
  • Using the graph, if you know the pressure and temperature you can determine the phase of water.
  • The solid lines—boundaries between phases—indicate temperatures and pressures at which the phases coexist (that is, they exist together in ratios, depending on pressure and temperature).

• The Structure and Properties of Water

  • Its liquid phase, the most common phase of water on Earth, is the form that is generally meant by the word "water."
  • When water achieves a specific critical temperature and a specific critical pressure (647 K and 22.064 MPa), the liquid and gas phases merge into one homogeneous fluid phase that shares properties of both gas and liquid.
  • Well-defined boundaries between solid and liquid, solid and gas, and liquid and gas.
  • During the phase transition between two phases (i.e, along these boundaries), the phases are in equilibrium with each other.
  • The three phases of water – liquid, solid, and vapor – are shown in temperature-pressure space.

• Thin Film Interference

  • This is a phenomenon that occurs when incident rays reflected by the upper and lower boundaries of a thin film interfere with one another and form a new wave.
  • Additionally, a phase shift of 180° or $\pi$radians may be introduced upon reflection at a boundary depending on the refractive indices of the materials on either side said boundary.
  • However, this condition may change if phase shifts occur upon reflection.
  • Demonstration of the optical path length difference for light reflected from the upper and lower boundaries.
  • The phase difference is the product of the optical path differene and the wave vector k.I hope it's of use!!

• Newton's Rings

  • An incident ray of light passes through the curved lens until it comes to the glass-air boundary, at which point it passes from a region of higher refractive index n (the glass) to a region of lower n (air).
  • At this boundary, some light is transmitted into the air, while some light is reflected.
  • The light that is transmitted into the air does not experience a change in phase and travels a a distance, d, before it is reflected at the flat glass surface below.
  • This second air-glass boundary imparts a half-cycle phase shift to the reflected light ray because air has a lower n than the glass.
  • If the path-length difference is an even multiple of λ/2, the reflected waves will be in phase with one another.

• Liquid to Gas Phase Transition

  • Vaporization of a sample of liquid is a phase transition from the liquid phase to the gas phase.
  • Vaporization of a sample of liquid is a phase transition from the liquid phase to the gas phase.
  • Gradually, Pw will rise as molecules escape from the liquid phase and enter the vapor phase.
  • At the same time, some of the vapor molecules will condense back into the liquid phase (step 2).
  • A bubble is a hole in a liquid; molecules at the liquid boundary are curved inward, so they experience stronger nearest-neighbor attractions.

• Pinckney's Treaty

  • Pinckney's Treaty between Spain and the United States defined the boundaries of the Spanish colonies of West and East Florida.
  • Primarily, it defined the boundaries between the United States and the Spanish colonies and guaranteed the United States navigation rights on the Mississippi River.
  • Among other things, the treaty ended the first phase of the West Florida Controversy, a dispute between the two nations over the boundaries of the Spanish colony of West Florida.
  • The boundary of Florida had been in dispute since the British had expanded the territory of the Florida colonies while it was in their possession.
  • The Spanish were not driven by a pressing desire to reopen trade routes to American merchants or to delineate a boundary line in the Florida territory.