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Questions and Answers
The reduced phase rule is given by the formula F = C − P + ______
The reduced phase rule is given by the formula F = C − P + ______
1
In the phase diagram, the 'x axis' shows composition in terms of [%A and %B] and the 'y axis' represents ______.
In the phase diagram, the 'x axis' shows composition in terms of [%A and %B] and the 'y axis' represents ______.
temperature (T)
The eutectic point is the specific point at which liquid and ______ are in equilibrium.
The eutectic point is the specific point at which liquid and ______ are in equilibrium.
both solids
A simple eutectic system has regions of all liquid at higher ______ and all solid at lower temperature.
A simple eutectic system has regions of all liquid at higher ______ and all solid at lower temperature.
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In a simple eutectic system, one region contains solid A at higher ______% and the other contains solid B at higher %B.
In a simple eutectic system, one region contains solid A at higher ______% and the other contains solid B at higher %B.
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The components A and B in the example of a simple eutectic system are naphthalene (C10H8) and ______ (C6H6).
The components A and B in the example of a simple eutectic system are naphthalene (C10H8) and ______ (C6H6).
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The phase diagram described has four regions: all liquid, all solid, and ______ regions of solid suspended in solution.
The phase diagram described has four regions: all liquid, all solid, and ______ regions of solid suspended in solution.
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The eutectic point can only be measured ______ and is characteristic of the system.
The eutectic point can only be measured ______ and is characteristic of the system.
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Pharmaceuticals can exist in multiple ______ and components.
Pharmaceuticals can exist in multiple ______ and components.
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The phase with the lowest free energy G at temperature T is the most ______ at that T.
The phase with the lowest free energy G at temperature T is the most ______ at that T.
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For solid phases, enthalpy H is large and ______.
For solid phases, enthalpy H is large and ______.
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Gas phases have enthalpy H close to ______.
Gas phases have enthalpy H close to ______.
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The Phase Rule states that F = C - P + ______.
The Phase Rule states that F = C - P + ______.
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At low temperatures T, solids tend to be the most ______ phase.
At low temperatures T, solids tend to be the most ______ phase.
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For gas phases, the entropy S is large and ______.
For gas phases, the entropy S is large and ______.
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Phase equilibria can be understood through the relationship G = H − ______S.
Phase equilibria can be understood through the relationship G = H − ______S.
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The temperature of melting or fusion is denoted as ______.
The temperature of melting or fusion is denoted as ______.
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At equilibrium, the free energies of both phases are equal, resulting in ______ G = 0.
At equilibrium, the free energies of both phases are equal, resulting in ______ G = 0.
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In a one component phase diagram, when F = 0, it indicates the ______ point.
In a one component phase diagram, when F = 0, it indicates the ______ point.
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When there are two phases in equilibrium, F equals ______.
When there are two phases in equilibrium, F equals ______.
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The general phase diagram for a pure substance shows the most stable phase at given pressure ______ and temperature T.
The general phase diagram for a pure substance shows the most stable phase at given pressure ______ and temperature T.
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Above the critical ______, a substance exists as a supercritical fluid.
Above the critical ______, a substance exists as a supercritical fluid.
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For carbon dioxide, the critical point is at a temperature of ______ °C.
For carbon dioxide, the critical point is at a temperature of ______ °C.
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At the triple point of water, the temperature is ______ °C.
At the triple point of water, the temperature is ______ °C.
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In a two component phase diagram, composition is plotted against constant ______.
In a two component phase diagram, composition is plotted against constant ______.
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In a phase diagram, a supercritical fluid combines aspects of both liquid and ______ phases.
In a phase diagram, a supercritical fluid combines aspects of both liquid and ______ phases.
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The A-B interactions are dependent on ______.
The A-B interactions are dependent on ______.
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The equation F = C − P + 2 relates to the number of ______ in a system.
The equation F = C − P + 2 relates to the number of ______ in a system.
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The stable phases shown in a phase diagram include solid, liquid, and ______.
The stable phases shown in a phase diagram include solid, liquid, and ______.
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At the upper critical temperature, the system can exhibit ______ liquid phases.
At the upper critical temperature, the system can exhibit ______ liquid phases.
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______ can occur when A-B involves complex formation.
______ can occur when A-B involves complex formation.
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In three-component systems, triangular phase diagrams represent the compositions of ______ components.
In three-component systems, triangular phase diagrams represent the compositions of ______ components.
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At point o in a triangular phase diagram, the composition is represented as ______.
At point o in a triangular phase diagram, the composition is represented as ______.
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In a two liquid phase system at lower critical temperature, A-A and B-B interactions are ______ than A-B.
In a two liquid phase system at lower critical temperature, A-A and B-B interactions are ______ than A-B.
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Hexane and aniline are examples of liquids that can exhibit ______ miscibility.
Hexane and aniline are examples of liquids that can exhibit ______ miscibility.
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The apices of a triangular phase diagram represent ______ components.
The apices of a triangular phase diagram represent ______ components.
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The systems involving alcohol, oil, and water typically require a ______ to stabilize the mixture.
The systems involving alcohol, oil, and water typically require a ______ to stabilize the mixture.
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At lower critical temperatures, the system may exhibit ______ solutions.
At lower critical temperatures, the system may exhibit ______ solutions.
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The composition of point A is 50% solubilizate, 30% ______, and 20% surfactant.
The composition of point A is 50% solubilizate, 30% ______, and 20% surfactant.
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At point B, the composition is 60% surfactant, 40% solubilizate, and ______% water.
At point B, the composition is 60% surfactant, 40% solubilizate, and ______% water.
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In the ternary phase diagram, pure oil, pure water, and pure ______ are the three corner points.
In the ternary phase diagram, pure oil, pure water, and pure ______ are the three corner points.
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A system can exist in two liquid phases when the compositions are ______ and 60% water.
A system can exist in two liquid phases when the compositions are ______ and 60% water.
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The upper critical point in the phase diagram is labeled as point ______.
The upper critical point in the phase diagram is labeled as point ______.
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Study Notes
Temperature
- A system with two components (A and B) can have four regions: all liquid, all solid, two regions of solid suspended in solution (one with solid A, the other with solid B), and a single point (the eutectic point) where liquid and both solids are in equilibrium.
- The eutectic point is the point where liquid and both solids are in equilibrium, at a fixed temperature and composition.
- The reduced phase rule (F = C − P + 1) is used to determine the number of degrees of freedom in a system.
Simple Eutectic System
- A simple eutectic system is characterized by a phase diagram with four regions: all liquid, all solid, two regions of solid suspended in solution, and a single eutectic point.
- The eutectic point is a characteristic of the system and can only be determined empirically.
- An example of a simple eutectic system is a mixture of naphthalene (C10H8) and benzene (C6H6).
Phases in Pharmaceuticals
- Phases are homogenous portions of physical material bounded by interfaces.
- A dosage formulation (medicine) will typically contain multiple phases and components.
- Pharmaceutically, there can be gas, multiple liquid, and multiple solid phases.
Phase Equilibria
- The phase with the lowest free energy (G) at a given temperature is the most stable at that temperature.
- For solid phases, enthalpy (H) is large and negative due to bonding between molecules, and entropy (S) is small due to low disorder. This means that solids are more stable at lower temperatures.
- For gas phases, enthalpy (H) is close to zero due to no bonding between molecules, and entropy (S) is large and positive due to high disorder. This means that gases are more stable at higher temperatures.
- Liquid phases are in between solid and gas phases.
G as a Function of T for a Pure Substance
- The free energy (G) of a pure substance is a function of temperature (T).
- The temperature of melting/fusion (Tfus) and the temperature of vaporization (Tvap) are points where the lines of the free energy of the different phases intersect.
- At the intersection points, the free energy of both phases is equal (ΔG = 0).
Mixtures of Phases and Components
- If a system has C components and P phases at equilibrium, each component can be present in each phase.
- Temperature (T) and pressure (P) can be varied.
- The Phase Rule (Gibbs) determines the number of degrees of freedom (F) that exist for changing parameters without producing or losing phases.
The Phase Rule
- The Phase Rule is expressed as F = C − P + 2.
- The "+ 2" accounts for variation in temperature and pressure.
- F represents the number of degrees of freedom, C represents the number of components, and P represents the number of phases.
- A system with one component and three phases in equilibrium (triple point) has zero degrees of freedom (F = 0).
- A system with one component and two phases in equilibrium has one degree of freedom (F = 1).
- Phase diagrams can be used to illustrate which phases are stable under specific conditions.
General Phase Diagram for a Pure Substance
- A general phase diagram for a pure substance shows which phase (solid, liquid, or vapor) is the most stable at a given pressure (P) and temperature (T).
- Triple points represent the points where three phases are in equilibrium.
- Critical points represent the points above which the substance exists as a supercritical fluid.
Two Component Phase Diagram
- Two-component phase diagrams are dependent on temperature and are plotted with composition vs. A-B interactions at constant pressure.
Two Liquids; Upper Critical Temperature
- The upper critical temperature is the temperature above which two liquids are fully miscible in all proportions (one liquid phase).
- Below the upper critical temperature, the two liquids are partially miscible (two liquid phases).
- Examples of systems that exhibit an upper critical temperature include hexane/aniline and hexane/nitrobenzene.
Two Liquids; Lower Critical Temperature
- The lower critical temperature is the temperature below which two liquids are fully miscible in all proportions (one liquid phase).
- Above the lower critical temperature, the two liquids are partially miscible (two liquid phases).
- Systems that exhibit a lower critical temperature often involve complex formation.
- Examples of systems that exhibit a lower critical temperature include triethylamine/water and paraldehyde/saline.
Three Component Systems
- Three-component systems can be illustrated using triangular (ternary) phase diagrams at constant temperature and pressure.
- The apices of the triangle represent the pure components.
- Points on the sides represent mixtures of two components.
- The composition of a point within the triangle can be determined by drawing lines from each apex to the point.
- The ratio of the lengths of the lines represents the ratio of the components in the mixture.
Alcohol (or Surfactant), Oil and Water Systems
- Alcohol (or surfactants) are fully miscible with water and oil in all proportions.
- Oil and water are partially miscible, meaning they only form one liquid phase at certain compositions.
- Ternary phase diagrams can be used to illustrate the phase behavior of these systems.
- Tie lines connect the compositions of the two liquid phases in equilibrium.
- Upper critical points represent the temperature above which the system becomes fully miscible.
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Description
Explore the fascinating world of eutectic systems through this quiz. You will learn about the different phases, the eutectic point, and the reduced phase rule. Test your knowledge on simple eutectic systems and their applications in pharmaceuticals.
