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Questions and Answers
Which of the following defines a phase?
Which of the following defines a phase?
A mixture of oil and water constitutes one phase.
A mixture of oil and water constitutes one phase.
False (B)
How many phases are present in a system containing ice, water, and water vapor at the freezing point?
How many phases are present in a system containing ice, water, and water vapor at the freezing point?
three
A gaseous mixture of nitrogen and hydrogen forms ______ phase.
A gaseous mixture of nitrogen and hydrogen forms ______ phase.
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Match the following examples with the number of phases present:
Match the following examples with the number of phases present:
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Which of the following is NOT a phase of matter?
Which of the following is NOT a phase of matter?
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Every solid constitutes a single phase, even when a solid solution is formed.
Every solid constitutes a single phase, even when a solid solution is formed.
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What is the number of phases in the following reaction? $Fe (s) + H_2O (g) \rightleftharpoons FeO (s) + H_2(g)$
What is the number of phases in the following reaction? $Fe (s) + H_2O (g) \rightleftharpoons FeO (s) + H_2(g)$
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In a system at equilibrium, what is the definition of a 'component'?
In a system at equilibrium, what is the definition of a 'component'?
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The water system, involving ice, liquid water, and vapor, is considered a two-component system because it exists in three different phases.
The water system, involving ice, liquid water, and vapor, is considered a two-component system because it exists in three different phases.
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In the thermal decomposition of $CaCO_3$ into $CaO$ and $CO_2$, how many components are present?
In the thermal decomposition of $CaCO_3$ into $CaO$ and $CO_2$, how many components are present?
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What occurs when crossing the curves on a phase diagram?
What occurs when crossing the curves on a phase diagram?
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When $NH_4Cl$ dissociates in a closed vessel and only $NH_4Cl$ is heated, the proportions of $NH_3$ and $HCl$ are ______.
When $NH_4Cl$ dissociates in a closed vessel and only $NH_4Cl$ is heated, the proportions of $NH_3$ and $HCl$ are ______.
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At the triple point, only two states of matter can coexist in equilibrium.
At the triple point, only two states of matter can coexist in equilibrium.
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When $NH_4Cl$ is heated in a closed vessel along with an excess of either $NH_3$ or $HCl$, how many components are in the system?
When $NH_4Cl$ is heated in a closed vessel along with an excess of either $NH_3$ or $HCl$, how many components are in the system?
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Match the following systems with the number of components:
Match the following systems with the number of components:
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What is the significance of the critical point on a phase diagram?
What is the significance of the critical point on a phase diagram?
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The curve on a phase diagram representing the transition between gaseous and solid states is called the ______ curve.
The curve on a phase diagram representing the transition between gaseous and solid states is called the ______ curve.
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The number of components in a system can be defined as the number of chemical constituents plus the number of equations relating those constituents in equilibrium.
The number of components in a system can be defined as the number of chemical constituents plus the number of equations relating those constituents in equilibrium.
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Match the curve on a phase diagram with the phase transition it represents:
Match the curve on a phase diagram with the phase transition it represents:
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For the reaction $2KClO_3(s)
ightleftharpoons 2KCl(s) + 3O_2(g)$, how many constituents are present?
For the reaction $2KClO_3(s) ightleftharpoons 2KCl(s) + 3O_2(g)$, how many constituents are present?
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According to the Gibbs Phase Rule, how many intensive variables can be independently specified at the triple point of water?
According to the Gibbs Phase Rule, how many intensive variables can be independently specified at the triple point of water?
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Water can only exist as a one-component system.
Water can only exist as a one-component system.
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Which type of system is presented when P=2; F=1?
Which type of system is presented when P=2; F=1?
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In a system with 2 phases and 1 component, how many degrees of freedom does the system have?
In a system with 2 phases and 1 component, how many degrees of freedom does the system have?
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Only one variable must be specified to define an univariant system.
Only one variable must be specified to define an univariant system.
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What is the normal melting point of ice in °C?
What is the normal melting point of ice in °C?
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In the reduction of Nickel Oxide, the reaction is NiO(s) + CO(g) = Ni(s) + _____(g).
In the reduction of Nickel Oxide, the reaction is NiO(s) + CO(g) = Ni(s) + _____(g).
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Match the following systems with their components:
Match the following systems with their components:
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How many independent components are necessary to specify the composition of each phase when additional CO is added to the system?
How many independent components are necessary to specify the composition of each phase when additional CO is added to the system?
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A binary phase diagram represents a system with three components.
A binary phase diagram represents a system with three components.
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What does a phase diagram represent?
What does a phase diagram represent?
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What is the temperature at the triple point of water?
What is the temperature at the triple point of water?
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The triple point allows for varying degrees of freedom in terms of pressure and temperature.
The triple point allows for varying degrees of freedom in terms of pressure and temperature.
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What happens to supercooled water upon slight disturbance?
What happens to supercooled water upon slight disturbance?
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Water can exist in ______ crystalline forms under high pressure.
Water can exist in ______ crystalline forms under high pressure.
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Why does ice melt at a lower temperature under high pressure?
Why does ice melt at a lower temperature under high pressure?
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Match the following crystalline forms of sulfur with their types:
Match the following crystalline forms of sulfur with their types:
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Metastable vapor pressure of supercooled water is lower than that of ice.
Metastable vapor pressure of supercooled water is lower than that of ice.
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What unique feature does the melting curve of ice/water exhibit?
What unique feature does the melting curve of ice/water exhibit?
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What is the freezing point of lead (Pb)?
What is the freezing point of lead (Pb)?
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The Pattinson’s process is used to obtain more silver from argentiferous lead.
The Pattinson’s process is used to obtain more silver from argentiferous lead.
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What happens when the temperature of the argentiferous lead is decreased along the line a-b?
What happens when the temperature of the argentiferous lead is decreased along the line a-b?
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The eutectic temperature represents the point where solid lead is in equilibrium with ______ composition.
The eutectic temperature represents the point where solid lead is in equilibrium with ______ composition.
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Match the areas on the phase diagram with their descriptions:
Match the areas on the phase diagram with their descriptions:
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At which point does the solid lead (Pb) begin to crystallize according to the phase diagram?
At which point does the solid lead (Pb) begin to crystallize according to the phase diagram?
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The phase diagram indicates that both lead and silver separate from liquid at point DBE.
The phase diagram indicates that both lead and silver separate from liquid at point DBE.
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What is indicated by the fixed temperature (C=2, P=3, F=0) in the phase diagram for the lead-silver system?
What is indicated by the fixed temperature (C=2, P=3, F=0) in the phase diagram for the lead-silver system?
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Flashcards
Phase
Phase
A physically distinct and mechanically separable part of a system.
Homogeneous Phase
Homogeneous Phase
A portion of a system with identical physical and chemical properties throughout.
Immiscible Liquids
Immiscible Liquids
Two liquids that do not mix, forming separate phases.
Miscible Liquids
Miscible Liquids
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Solid Solution
Solid Solution
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Polymorphism
Polymorphism
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Gaseous Phase
Gaseous Phase
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Heterogeneous Mixture
Heterogeneous Mixture
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Phase change
Phase change
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Triple point
Triple point
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Critical point
Critical point
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Fusion curve
Fusion curve
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Vaporization curve
Vaporization curve
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Sublimation curve
Sublimation curve
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Gibbs Phase Rule
Gibbs Phase Rule
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Degrees of freedom
Degrees of freedom
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Component
Component
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One Component System
One Component System
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Two Component System
Two Component System
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Equilibrium State
Equilibrium State
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Dissociation
Dissociation
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Chemical Constituents
Chemical Constituents
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Number of Components Formula
Number of Components Formula
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Thermal Decomposition
Thermal Decomposition
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Univariant System
Univariant System
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Independent Components
Independent Components
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Phase Diagram
Phase Diagram
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Binary Diagram
Binary Diagram
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Ternary Diagram
Ternary Diagram
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Heterogeneous Equilibria
Heterogeneous Equilibria
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Component (C)
Component (C)
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Metastable Curve
Metastable Curve
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Supercooling
Supercooling
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Polymorphism in Ice
Polymorphism in Ice
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Negative Slope of Melting Curve
Negative Slope of Melting Curve
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Orthorhombic Sulfur
Orthorhombic Sulfur
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Monoclinic Sulfur
Monoclinic Sulfur
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Freezing point of lead
Freezing point of lead
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Freezing point of silver
Freezing point of silver
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Eutectic point
Eutectic point
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Pattinson’s Process
Pattinson’s Process
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Crystallization of lead
Crystallization of lead
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Liquid phase
Liquid phase
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Solid mixture
Solid mixture
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Equilibrium composition
Equilibrium composition
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Study Notes
Phase Rule
- A phase is a chemically homogeneous, physically distinct, and mechanically separable part of a system. Solid, liquid, and gas are three phases of matter.
- A phase is considered "homogeneous" if it has the same properties and chemical composition throughout.
- A gas or gaseous mixture is a single phase. Totally miscible liquids also constitute a single phase.
- In an immiscible liquid system, each layer is a separate phase.
- Every solid is a single phase unless a solid solution is formed. A solid solution is considered a single phase.
- Polymorphic forms of a substance (e.g., calcite and aragonite, graphite and diamond) are separate phases.
- Components refer to the minimal number of independent variables required to describe the composition of each phase in equilibrium.
- For example, in a water system (ice, water, vapor), the chemical composition of all three phases is H₂O. Hence, it is a one-component system. Similarly, the sulfur system (rhombic, monoclinic, liquid, vapor) is also a one-component system since the chemical composition of all phases is S.
- Components (C) of a system are the chemical species that independently define the composition of each phase in equilibrium.
- Degrees of freedom (F) or variance is the minimum number of independent variables (e.g., temperature, pressure, concentration) needed to define the system completely.
Degrees of Freedom
- F = 3: trivariant (system can be changed readily)
- F = 2: divariant (two variables need to be fixed)
- F = 1: univariant (one variable needs to be fixed, the others are determined)
- F = 0: invariant (no variables can change independently)
- If F < 0, there must be disequilibrium
Gibbs Phase Rule
- F = C - P + 2
- F = degrees of freedom
- C = number of components
- P = number of phases
Types of Phase Diagrams
- Unary diagrams involve a single component.
- Binary diagrams involve two components.
- Ternary diagrams involve three components
Examples of Heterogeneous Equilibria
- Liquid-Vapor
- Solid-Vapor
- Solid-Liquid
- Solid 1-Solid 2
- Solubility of solids, liquids, gases
- Vapor pressure of solutions
- Chemical reactions between solids or liquids and gases
- Distribution of solutes between different phases
Phase Diagrams
- A graphical representation of a substance's physical states under varying temperature and pressure conditions.
- Pressure on y-axis
- Temperature on x-axis
- Lines/curves indicate phase transitions.
- Two states of the substance coexist in equilibrium on the lines/curves.
Triple Point and Critical Point
- Triple point: point on a phase diagram where three states (gas, liquid, solid) coexist.
- Critical point: point on a phase diagram where the distinction between liquid and gaseous states disappears.
Fusion, Vaporization, and Sublimation Curves
- Fusion (melting/freezing): transition between liquid and solid states.
- Vaporization (condensation): transition between gaseous and liquid states.
- Sublimation (deposition): transition between gaseous and solid states.
How Many Intensive Variables Can Be Specified at the Triple Point of Water
- The triple point is unique since degrees of freedom (F) are 0. Therefore, no intensive variables can be independently specified.
Water (H₂O) Phase Equilibria
- H₂O is a single-component system.
- F = 3 - P
- One can have three cases:
- P=1; F=2(bivariant)
- P=2; F=1(univariant)
- P=3; F=0(invariant)
Eutectic Systems
- A eutectic system is a mixture that solidifies at a lower temperature than any other composition of the same ingredients.
- Eutectic composition represents the point at which the mixture solidifies at the lowest temperature.
- The eutectic point is the intersection of the eutectic temperature and composition lines on a phase diagram.
Pattinson's Process
- A process for separating silver from argentiferous lead.
- Involves melting and slowly cooling the argentiferous lead.
- Lead solidifies first, separating from the remaining liquid phase, this liquid gets richer in silver.
- Separated lead is removed by ladles during the process.
Phase Diagram of Saltwater
- A phase diagram for a solution of salt in water. It illustrates the equilibrium conditions between the salt crystals, the saltwater solution, and ice-saltwater mixtures. The curves for phase transitions are influenced by the concentration of salt in the water. The phase diagram depicts the states of equilibrium based on the concentration and temperature.
Merits of Phase Rule
- Applicable to both physical and chemical equilibria.
- No molecular structure information needed.
- Convenient method for classifying equilibrium states.
- Predicts a system's behavior across various sets of parameters.
Limitations of Phase Rule
- Applicable only to systems in equilibrium.
- Deals only with a single equilibrium system.
- Requires utmost care to determine the number of phases involved rather than the quantities.
- Requires all phases to be present and not finely divided for accurate results.
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Description
Test your understanding of phases in chemistry with this quiz. You'll explore concepts such as the number of phases in different states of matter, equilibrium, and phase diagrams. Ideal for chemistry students looking to reinforce their knowledge of phase systems.
