Reading Phase Diagrams
Reading a Phase Diagram. So how do you read a phase diagram.
For one component systems the equilibrium state of the system is defined by two independent parameters P and T T and V or P and V.
Reading phase diagrams. As long as you are at 100 C you can change the phase by changing the pressure on the system. Standard phase diagrams show how phases or phase assemblages change as a function of temperature pressure phase composition or combinations of these variables. Standard phase diagrams are graphical representations of the equilibrium relationships between minerals or others phases.
The binary eutectic phase diagram explains the chemical behavior of two immiscible unmixable crystals from a completely miscible mixable melt such as olivine and pyroxene or pyroxene and Ca plagioclase. This phase diagram Phase Diagram shows a typical binary system that happens to contain a eutectic. A typical phase diagram consists of discrete regions that represent the different phases exhibited by a substance Figure 124.
The phase diagram of an alloy made of components A and B for all combinations of Tand WBor XB defines the. But it doesnt have to be horizontal. Reading a Ternary Diagram A ternary diagram is a triangle with each of the three apexes representing a composition such as sandstone shale and limestone.
Phase diagrams are divided into three single phase regions that cover the pressure-temperature space over which the matter being evaluated exists. Where the phases are. In the cases well be looking at on this page the phases will simply be the solid liquid or vapour gas states of a pure substance.
Phase diagrams A phase diagram lets you work out exactly what phases are present at any given temperature and pressure. First lets consider the information that is displayed. This is a fairly common characteristic of bimetallic alloys the copper-silver system for instance has a phase diagram very similar to the one in the link.
Phase diagramis a graphical representation of all the equilibriumphases as a function of temperature pressure and composition. Imagine a vertical line through this diagram-- for water choose 100 degrees C. Reading values on the ternary plot The advantage of using a ternary plot for depicting chemical compositions is that three variables can be conveniently plotted in a two-dimensional graph.
This is the phase diagram for a. 3 is called the liquidus. Boiling points melting points and sublimation points vary with pressure.
Ternary plots can also be used to create phase diagrams by outlining the composition regions on the plot where different phases exist. Sional 2-D sections of any multicomponent phase diagram whether it is an isotherm or an isopleth can be read by focusing on two lines that refer to one particular phase. System the phase diagram usually has the general appearance of that shown in Fig.
What you need to know. Here we are going to generalize to two minerals A and B or P and Q. In this phase diagram which is typical of most substances the solid lines represent the phase boundaries.
The diagram consists of two single-phase fields separated by a two-phase field. Phase diagrams can be used to understand under which conditions a pure sample of matter exists in two or three state equilibrium by examining the phase boundaries and the triple point. How to Read a Phase Diagrams Everybody remembers that the boiling point of water is 100C but thats only true at a certain pressure 1 bar.
Each region corresponds to the range of combinations of temperature and pressure over which that phase is stable. In the video here Sal uses a horizontal line through the phase diagram. This lesson will define and locate the triple point and critical point on a phase diagram and illustrate how to extract other specific date points from the graph.
A phase diagram helps show what phase exist at what temperature and pressure. A phase diagramor equilibrium diagram is a diagram with Tand composition as axes showing the equilibrium constitution. That between the two-phase field and solid field is the solidus.
The green line marks the freezing point or transition from liquid to solid the blue line marks the boiling point or transition from liquid to gas and the red line shows the conditions under which a solid can be converted directly to a gas and vice-versa. These relationships are governed by the laws of thermodynamics. The boundary between the liquid field and the two-phase field in Fig.
Liquid gaseous and solid states. This chemistry video tutorial explains the concepts behind the phase diagram of CO2 Carbon Dioxide and the phase diagram of water H2O. The combination of high pressure and low temperature upper left of Figure 124.
