Thermodynamics Unit I: Basic Concepts
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Questions and Answers

What is the primary focus of thermodynamics?

  • The behavior of substances at absolute zero
  • The transformation and effects of energy on physical properties (correct)
  • The study of molecular interactions
  • The analysis of heat and work in mechanical systems

    • Which of the following is a characteristic of a closed system?

  • The volume of the system is fixed
  • Only energy can cross its boundary
  • Mass cannot cross its boundary, but the volume can change (correct)
  • Mass and energy can cross its boundary

    • What is the term for the surface that separates the system from the surrounding?

  • Perimeter
  • Control surface
  • Boundary (correct)
  • Interface

    • Which approach to thermodynamic studies considers the molecular level of events?

    <p>Microscopic approach</p> Signup and view all the answers

    What is the term for a region in space chosen for thermodynamic study?

    <p>System</p> Signup and view all the answers

    Which of the following is an example of an open system?

    <p>All of the above</p> Signup and view all the answers

    What is the primary goal of thermodynamic studies?

    <p>To understand the relationship between heat and work</p> Signup and view all the answers

    Which approach to thermodynamic studies is used in the study of classical thermodynamics?

    <p>Macroscopic approach</p> Signup and view all the answers

    What is the term for the mass and region outside the system?

    <p>Surrounding</p> Signup and view all the answers

    Which of the following properties is required to describe a system in thermodynamic studies?

    <p>Pressure</p> Signup and view all the answers

    What is the main characteristic of microscopic approach in thermodynamics?

    <p>It considers the matter as comprised of a large number of tiny particles known as molecules, which move randomly in a disordered fashion.</p> Signup and view all the answers

    What is the term for the properties of a system that are independent of the size of the system?

    <p>Intensive properties</p> Signup and view all the answers

    What is the term for the extensive properties per unit mass of a system?

    <p>Specific properties</p> Signup and view all the answers

    What is the condition of a system at any instant of time called?

    <p>State</p> Signup and view all the answers

    What is the term for a state of balance where there are no unbalanced potentials or driving forces within the system?

    <p>Equilibrium</p> Signup and view all the answers

    What is the term for a change that a system goes from one equilibrium state to another equilibrium state?

    <p>Process</p> Signup and view all the answers

    What is the term for the series of states through which a system passes during a process?

    <p>Path</p> Signup and view all the answers

    What is the term for the density of a substance with respect to density of some standard substance at a specified temperature?

    <p>Specific gravity</p> Signup and view all the answers

    What is the term for the quotient of the substance's volume to its mass?

    <p>Specific volume</p> Signup and view all the answers

    What is the assumption made in the continuum idealization?

    <p>The properties of the system vary continually in space with no jump discontinuities.</p> Signup and view all the answers

    What is the characteristic of a quasi-equilibrium process?

    <p>The system remains infinitesimally close to an equilibrium state at all times</p> Signup and view all the answers

    Which of the following is an example of a point function?

    <p>Temperature</p> Signup and view all the answers

    What is the relation between the Kelvin scale and the Celsius scale?

    <p>T(K) = T(C) + 273.16</p> Signup and view all the answers

    What is the unit of pressure in the SI system?

    <p>N/m2</p> Signup and view all the answers

    What is the condition for a system to be in a state of thermodynamic equilibrium?

    <p>No changes in macroscopic properties</p> Signup and view all the answers

    What is the relation between the absolute pressure and gauge pressure?

    <p>Pgauge = pabs - patm</p> Signup and view all the answers

    What is the characteristic of a cycle?

    <p>The system returns to its initial state at the end of the process</p> Signup and view all the answers

    What is the definition of temperature?

    <p>A measure of the hotness or coldness of a substance</p> Signup and view all the answers

    What is the relation between the Rankine scale and the Fahrenheit scale?

    <p>T(R) = T(F) + 459.67</p> Signup and view all the answers

    What is the condition for mechanical equilibrium?

    <p>Equality of pressure</p> Signup and view all the answers

    What is the condition for a system to be in chemical equilibrium?

    <p>The chemical composition of the system does not change with time</p> Signup and view all the answers

    Which of the following is a characteristic of a quasi-static process?

    <p>Infinite slowness</p> Signup and view all the answers

    What is the difference between a reversible and an irreversible process?

    <p>A reversible process can be executed in either direction, while an irreversible process cannot</p> Signup and view all the answers

    What is the formula for calculating work in physics?

    <p>W=F·d·cos(?)</p> Signup and view all the answers

    What is the unit of work in the International System of Units (SI)?

    <p>Joule</p> Signup and view all the answers

    What is the type of work that occurs when a system undergoes a change in volume or pressure?

    <p>Pressure-Volume Work</p> Signup and view all the answers

    What is the sign convention for work done by a system on the surroundings?

    <p>Positive</p> Signup and view all the answers

    What is the equation that relates the change in internal energy (?U) to heat (Q) and work (W)?

    <p>?U=Q-W</p> Signup and view all the answers

    What is an example of a reversible process?

    <p>Frictionless isothermal expansion of a fluid</p> Signup and view all the answers

    What is the definition of thermodynamic work?

    <p>Work is said to be done by a system if the sole effect on things external to the system can be reduced to the raising of a weight</p> Signup and view all the answers

    Study Notes

    Thermodynamics Introduction

    • Thermodynamics is the science of energy and its transformation, and its effects on physical properties of substances.
    • Deals with equilibrium and feasibility of a process.
    • Involves the relationship between heat and work and properties of systems in equilibrium.

    Thermodynamic System

    • Defined as a quantity of matter or a region in space chosen for study.
    • The mass and region outside the system is called the surrounding.
    • The boundary that separates the system from the surrounding can be real or imaginary.

    Types of Systems

    • Closed System (Control Mass):
      • Consists of a fixed amount of mass.
      • No mass can cross its boundary or leave/enter.
      • Energy in the form of heat or work can cross the boundary.
      • Volume does not have to be fixed.
      • Example: piston-cylinder device.
    • Open System (Control Volume):
      • A properly selected region in space.
      • Both mass and energy can cross the boundary.
      • Boundary is called a control surface and can be real or imaginary.
      • Example: compressor, turbine, nozzle.

    Approaches to Thermodynamic Study

    • Macroscopic Approach:
      • Considers a certain quantity of matter without considering molecular-level events.
      • Requires simple mathematical formulae.
      • Used in classical thermodynamics.
      • Concerned with overall behavior of the system.
      • Few properties are required to describe the system.
    • Microscopic Approach:
      • Considers matter to be comprised of many tiny particles (molecules) that move randomly.
      • Effects of molecular motion are considered.
      • Requires advanced statistical and mathematical methods.
      • Used in statistical thermodynamics.
      • Requires knowledge of the structure of matter.

    Properties of a System

    • Property: Any characteristic of a system.
    • Intensive Properties:
      • Independent of the size of the system.
      • Examples: temperature, pressure, density.
      • Not additive.
      • Value remains the same whether considering the whole system or a part of it.
    • Extensive Properties:
      • Dependent on the size or extent of the system.
      • Examples: mass, volume, total energy.
      • Additive.
      • Value for an overall system is the sum of its values for the parts into which the system is divided.

    Specific Properties

    • Specific Properties: Extensive properties per unit mass.
    • Specific Volume: The volume of a substance per unit mass.
    • Specific Energy: Energy per unit mass.
    • Specific Gravity (or Relative Density): Density of a substance with respect to a standard substance at a specified temperature.

    Continuum and State

    • Continuum: A continuous, homogeneous matter with no holes.
    • State: The condition of a system at any instant of time, described by its properties.
    • Equilibrium: A state of balance where there are no unbalanced potentials within the system.

    Processes and Path Functions

    • Process: A change that a system undergoes from one equilibrium state to another.
    • Path Function: A quantity whose value depends on the path followed during a change of state.
    • Point Function: A quantity whose change is independent of the path.
    • Quasi-Equilibrium Process: A process that proceeds in such a way that the system remains infinitesimally close to an equilibrium state at all times.

    Temperature and Pressure

    • Temperature: A measure of hotness or coldness.
    • Pressure: Force exerted by a fluid per unit area.
    • Pressure Scales: Related to absolute temperature scales.
    • Kelvin Scale: Related to Celsius scale by T(K) = T(C) + 273.16.
    • Rankine Scale: Related to Fahrenheit scale by T(R) = T(F) + 459.67.

    Thermodynamic Equilibrium

    • Thermodynamic Equilibrium: A state where no changes in macroscopic properties are observed if the system is isolated from its surroundings.
    • Conditions for Equilibrium:
      • Thermal equilibrium (equality of temperature).
      • Mechanical equilibrium (equality of pressure).
      • Chemical equilibrium (equality of chemical potential).

    Reversible and Irreversible Processes

    • Reversible Process: A process that can be executed in either direction without producing any changes in the rest of the universe.
    • Irreversible Process: A process that cannot be restored to its initial state without producing changes in the rest of the universe.

    Work and Heat Transfer

    • Thermodynamic Work: Energy transfer that occurs when a system undergoes a change in volume or pressure.
    • Pressure-Volume Work (PV Work): Work done by or on a system at constant pressure.
    • Sign Convention: Work done by the system is positive, and work done on the system is negative.

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    Description

    Introduction to thermodynamics, a science dealing with energy transformation and its effects on physical properties of substances. Covers equilibrium, feasibility, and relationships between heat, work, and system properties.

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