Lec-18 I The water system I Applied Chemistry I Chemical Engineering

Chemical Engineering Department_LJIET
29 Jul 202112:34
EducationalLearning
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TLDRThe video lecture from the Energy Institute of Engineering and Technology delves into the concept of the phase rule (f = c - p + 2) and its application in understanding the behavior of chemical systems under varying conditions of concentration, pressure, and temperature. The session focuses on one-component systems, using the water system as a primary example to illustrate degrees of freedom, phase diagrams, and the characteristics of the triple point. The lecture also discusses different features of the phase diagram, including curves representing sublimation, melting, and vapor pressure, as well as areas and points of interest such as the supercooled condition. This comprehensive overview provides a solid foundation for further studies in applied chemistry.

Takeaways
  • ๐Ÿ“š The lecture series is on Applied Chemistry, with the subject code 313050506.
  • ๐Ÿ“ˆ The Phase Rule (f = c - p + 2) is essential for understanding the effects of concentration, pressure, and temperature on chemical equilibria.
  • ๐Ÿ” In a one-component system, the degrees of freedom (f) can be calculated using the formula f = 3 - p, where p is the number of phases.
  • ๐ŸŒก๏ธ The triple point refers to the equilibrium of all three phases (solid, liquid, vapor) of a substance, exemplified by water's triple point at 0ยฐC and 0.0078 atmospheres.
  • ๐Ÿ“Š A phase diagram of a substance, like water, can be represented on a graph with pressure on one axis and temperature on the other, typically in Celsius and atmospheres.
  • ๐ŸงŠ The sublimation curve on a phase diagram shows the direct conversion of a solid to a gas, illustrating the relationship between pressure and the substance's vapor pressure.
  • ๐ŸŒ€ The melting curve (ice to water) demonstrates the equilibrium between solid ice and liquid water, with the melting point changing under different pressures.
  • ๐Ÿ’ง The vapor pressure curve represents the equilibrium between liquid water and water vapor at various temperatures, with the boiling point indicated at 100ยฐC under standard atmospheric pressure.
  • ๐Ÿ”„ Metastable systems or supercooled conditions can occur in a substance, such as water, where the substance remains in a liquid state below its freezing point due to slowed molecular motion.
  • ๐Ÿ” Understanding the different features of a phase diagram, including curves, areas, and points, is crucial for analyzing the behavior of substances under varying conditions.
Q & A

  • What is the subject code for Applied Chemistry in the video lecture series?

    -The subject code for Applied Chemistry is 313.

  • What does the Phase Rule help us understand?

    -The Phase Rule helps us understand the effect of changing parameters such as concentration, pressure, and temperature on the equilibria of chemical systems.

  • How is the Phase Rule mathematically represented?

    -The Phase Rule is mathematically represented as F = C - P + 2, where F is the degrees of freedom, C is the number of components, P is the number of phases, and 2 is a constant.

  • What is the degree of freedom for a system of ice and water vapor?

    -The degree of freedom for a system of ice and water vapor is zero, as F = 0 (since there is no degree of freedom allowed).

  • What is the degree of freedom for a system containing pure gas?

    -The degree of freedom for a system containing pure gas is two, as F = 2 (indicating two degrees of freedom are allowed).

  • What is a one-component system and how is its Phase Rule equation written?

    -A one-component system is a system that involves only one chemical entity. The Phase Rule equation for such a system is written as F = 1 - P + 2, where F is the degrees of freedom, and P is the number of phases.

  • What is the triple point in a one-component system?

    -The triple point in a one-component system is the point where all three phases (solid, liquid, and vapor) are in equilibrium with each other.

  • How can the phase diagram of a water system be represented?

    -The phase diagram of a water system can be represented using two axes, with pressure on one axis and temperature on the other, typically in Celsius for temperature and atmospheres for pressure.

  • What are the three different features that can be observed in the phase diagram of a water system?

    -The three different features that can be observed in the phase diagram of a water system are curves, areas, and points.

  • What is the significance of the vapor pressure curve (curve OA) in the phase diagram?

    -The vapor pressure curve (curve OA) represents the vapor pressure of liquid water at different temperatures, showing where the liquid water and water vapor coexist in equilibrium.

  • How does the sublimation curve (curve OC) depict the effect of pressure on the melting point of ice?

    -The sublimation curve (curve OC) shows the direct conversion from solid to gas (sublimation) and depicts that the melting point of ice is lowered by an increase in pressure, as per Le Chatelier's principle.

Outlines
00:00
๐Ÿ“š Introduction to Applied Chemistry and the Phase Rule

This paragraph introduces the video lecture series on applied chemistry, focusing on the subject code 313050606. It begins with a discussion on the phase rule, which is a fundamental concept for understanding the effects of changing parameters such as concentration, pressure, and temperature on the equilibria of chemical systems. The phase rule is mathematically expressed as F = c - p + 2, where F represents the degrees of freedom, c is the number of components, and p is the number of phases. The lecture then delves into examples of degrees of freedom in various systems, such as the eyes vapor and water system, water and water vapor, pure gas system, and mixtures of gases, highlighting how the degrees of freedom change depending on the system's composition and phase equilibrium.

05:02
๐Ÿ“ˆ Phase Diagrams and the Triple Point in Water Systems

This paragraph continues the discussion on applied chemistry by focusing on phase diagrams and the triple point in water systems. It explains how a phase diagram is constructed using pressure and temperature axes, with celsius as the unit for temperature and atmospheres for pressure. The paragraph describes various points and curves on the phase diagram, such as the freezing point, triple point, and boiling point, as well as the sublimation, melting, and vapor pressure curves. It also discusses the concept of supercooling and metastable conditions. The lecture aims to provide a comprehensive understanding of how these features can be mathematically represented using the phase rule and how they manifest in the water system under different conditions.

10:03
๐ŸŒก๏ธ Vapor Pressure and Sublimation in Water Systems

In this paragraph, the lecture focuses on the vapor pressure curve and sublimation curve within water systems. It explains how the vapor pressure curve represents the equilibrium between liquid water and water vapor at different temperatures, leading to the boiling point at 100 degrees Celsius under standard atmospheric pressure. The sublimation curve, on the other hand, illustrates the direct conversion of solid ice to water vapor and shows how pressure affects the melting point of ice. The lecture emphasizes understanding the degrees of freedom for each phase equilibrium and how they can be calculated using the phase rule. It concludes by setting the stage for further discussion in the next session, providing a solid foundation for understanding complex chemical systems and their behavior under varying conditions.

Mindmap
Keywords
๐Ÿ’กApplied Chemistry
Applied Chemistry refers to the practical application of chemistry principles to solve real-world problems. In the context of the video, it is the subject being taught, with a focus on understanding how changing parameters such as concentration, pressure, and temperature affect the equilibria of chemical systems.
๐Ÿ’กPhase Rule
The Phase Rule, mathematically expressed as f = c - p + 2, is a fundamental principle in the study of phase equilibria in chemical systems. It helps to predict the number of degrees of freedom in a system, which is the number of independent variables that can be changed without disrupting the equilibrium.
๐Ÿ’กDegrees of Freedom
Degrees of Freedom refers to the number of independent variables that can be changed in a system without changing the system's phase. In the context of the video, it is used to describe the flexibility in altering conditions such as pressure or temperature in a chemical system while maintaining equilibrium.
๐Ÿ’กTriple Point
The Triple Point is a specific condition in a phase diagram where three phases of a substance coexist in equilibrium. It represents a unique point where the solid, liquid, and vapor phases are all in equilibrium with each other under specific conditions of temperature and pressure.
๐Ÿ’กPhase Diagram
A Phase Diagram is a graphical representation that shows the equilibrium conditions between different phases of a substance. It typically uses axes for pressure and temperature, and it illustrates the regions where each phase or combination of phases is stable.
๐Ÿ’กVapor Pressure
Vapor Pressure is the pressure exerted by a vapor in equilibrium with its condensed phases at a given temperature. It is an important concept in understanding the transition from liquid to gas and how it is influenced by temperature.
๐Ÿ’กSublimation
Sublimation is the process by which a substance transitions directly from the solid phase to the gas phase without passing through the liquid phase. It is an example of a phase change that can be influenced by changes in pressure and temperature.
๐Ÿ’กMelting
Melting is the process of a solid substance turning into a liquid upon heating. It is a phase transition that occurs at a specific temperature, known as the melting point, and is an important concept in understanding the behavior of substances under varying thermal conditions.
๐Ÿ’กSupercooling
Supercooling is a phenomenon where a liquid remains stable and does not freeze even below its normal freezing point. This occurs when the liquid is cooled quickly or in the absence of impurities that could act as nucleation sites for ice crystals.
๐Ÿ’กMetastable System
A Metastable System is a state of a substance that is not at equilibrium but is็จณๅฎš็š„ due to slow kinetics that prevent it from reaching equilibrium. In the context of the video, it refers to conditions such as supercooling where the substance exhibits unusual but stable behavior.
๐Ÿ’กEquilibrium
Equilibrium in chemistry refers to a state where the rates of the forward and reverse reactions are equal, and there are no net changes in the concentrations of reactants and products. It is a crucial concept in understanding how chemical systems behave under different conditions.
Highlights

The lecture series is on Applied Chemistry with the subject code 313050506.

The Phase Rule is discussed, which helps understand the effects of changing parameters such as concentration, pressure, and temperature on the equilibria of chemical systems.

The mathematical representation of the Phase Rule is given as f = c - p + 2.

Examples of degrees of freedom in different systems are provided, such as ice-water vapor system with no degrees of freedom (f=0).

For water and water vapor system, the degrees of freedom is one (f=1).

In a pure gas system, there are two degrees of freedom (f=2).

For mixtures of gases, there are three degrees of freedom (f=3).

A one-component system is explained, with the Phase Rule equation written as f = c - p + 2, and for a single component, it becomes f = 3 - p.

The concept of the triple point is introduced, where solid, liquid, and vapor are in equilibrium with each other.

The phase diagram of the water system is described, using pressure on one axis and temperature on another.

The freezing point, triple point, and boiling point of water are identified on the phase diagram.

Different curves on the phase diagram are explained, including the sublimation curve, melting curve, and vapor pressure curve.

The triple point is further explained as the point where all three phases coexist with zero degrees of freedom.

The areas on the phase diagram are discussed, with each representing different phase equilibria and degrees of freedom.

The metastable or supercooled condition of water system is mentioned as an observable feature.

The vapor pressure curve (OA) is described, showing the equilibrium between water and water vapor at different temperatures.

The sublimation curve (OC) is explained, depicting the direct conversion of solid ice to water vapor and the effect of pressure on the melting point of ice.

Transcripts

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AppliedChemistryPhaseRuleChemicalEquilibriaWaterSystemTriplePointVaporPressureSublimationMeltingPointScientificLectureEngineeringTech