Thermodynamics: Internal Energy Concepts
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Questions and Answers

In an isobaric process, which variable remains constant throughout the process?

  • Internal Energy
  • Pressure (correct)
  • Volume
  • Temperature

    • In which scenario would the isobaric process typically be considered?

  • When volume changes significantly
  • When temperature changes significantly
  • When processes are conducted in a closed vessel
  • When processes are carried out in an open vessel (correct)

    • What is the work done during an isochoric process?

  • Dependent on temperature change
  • Negative pressure work
  • Zero (correct)
  • Equal to PV

    • For an isothermal process involving an ideal gas, what is the change in internal energy?

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

    What is the relationship between pressure and volume for an isothermal process?

    <p>PV = Constant</p> Signup and view all the answers

    Which statement about the change in enthalpy (DH) during an isothermal process involving ideal gas is correct?

    <p>DH is zero</p> Signup and view all the answers

    What characterizes an ideal gas during isothermal and isobaric processes?

    <p>Moles of gas are constant</p> Signup and view all the answers

    Why is the work done during an isothermal reversible process greater than that in an adiabatic process?

    <p>Adiabatic processes do not allow for heat exchange</p> Signup and view all the answers

    What does a negative sign for dV indicate during compression?

    <p>Work is done on the system.</p> Signup and view all the answers

    What unit of work corresponds to 1 atm × litre?

    <p>101.3 J</p> Signup and view all the answers

    What does the work done (dW) equate to in relation to pressure and volume changes?

    <p>dW = -Pext.dV</p> Signup and view all the answers

    In terms of heat, what does a positive sign represent?

    <p>Heat absorbed by the system.</p> Signup and view all the answers

    How does the internal energy of a system change when it gains energy from the surroundings?

    <p>It increases.</p> Signup and view all the answers

    What is the relationship between calories and joules based on the given conversions?

    <p>1 J = 0.24 cal</p> Signup and view all the answers

    What happens to the temperature of a system when it acquires energy from a cooler surrounding?

    <p>The temperature of the system increases.</p> Signup and view all the answers

    During expansion, how is work done characterized?

    <p>Positive work on the surroundings.</p> Signup and view all the answers

    Which statement about internal energy is true?

    <p>Internal energy is a state function.</p> Signup and view all the answers

    Why can't the absolute value of internal energy be calculated?

    <p>The exact values of all energy types can't be determined simultaneously.</p> Signup and view all the answers

    Which of the following describes an extensive property?

    <p>Internal energy is an extensive property.</p> Signup and view all the answers

    What is the relationship between internal energy and pressure for 1 mole of an ideal gas?

    <p>Internal energy equals kinetic energy at constant pressure.</p> Signup and view all the answers

    Which of the following statements regarding thermal equilibrium is correct?

    <p>Two systems can be in thermal equilibrium without interacting.</p> Signup and view all the answers

    Which type of thermodynamic property is independent of mass?

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

    What aspect of a cyclic process prevents a change in internal energy?

    <p>It returns to its initial state.</p> Signup and view all the answers

    Which of the following types of energy is excluded from the calculation of internal energy?

    <p>Gravitational potential energy.</p> Signup and view all the answers

    What is the system type for a helium-filled balloon?

    <p>Closed system</p> Signup and view all the answers

    Which is an example of an extensive property?

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

    What type of macroscopic energy changes are complexities not included in internal energy?

    <p>Collective behaviors of individual entities.</p> Signup and view all the answers

    What type of thermodynamic system is represented by a refrigerator cycle?

    <p>Closed system</p> Signup and view all the answers

    Which of the following is an example of an intensive property?

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

    Which of the following statements about extensive properties is true?

    <p>They depend on the mass of the system.</p> Signup and view all the answers

    What characterizes a thermodynamic state function?

    <p>It depends on the initial and final state.</p> Signup and view all the answers

    Which of the following is NOT an intensive property?

    <p>Heat capacity</p> Signup and view all the answers

    What is the work done in cal during the reaction of 260 g Zn with HCl?

    <p>–3200 cal</p> Signup and view all the answers

    In the equation, W = -2303 nRT log H, what does 'n' represent?

    <p>Number of moles</p> Signup and view all the answers

    What is the final temperature after the change of 22 gm CO2 from 500 ml, 300 K to 4L?

    <p>150 K</p> Signup and view all the answers

    What does the term Dng represent in the context of the reactions?

    <p>Number of moles of gas produced</p> Signup and view all the answers

    What is the work done in cal when 22 gm CO2 changes under reversible and adiabatic conditions?

    <p>–450 cal</p> Signup and view all the answers

    In the reaction equation Zn (s) + 2HCl (l) → ZnCl2 (s) + H2 (g), how many moles of Zn are represented by 260 g?

    <p>4 moles</p> Signup and view all the answers

    What is the value of R in the work done equation W = DngRT?

    <p>1.987 cal/(K mol)</p> Signup and view all the answers

    How is the total work done calculated during gas expansion within a system?

    <p>By multiplying the change in number of moles by temperature and R</p> Signup and view all the answers

    Study Notes

    Internal Energy

    • Internal energy (E or U) is the sum of various types of energies associated with a system.
    • Internal energy includes potential energy, kinetic energy, thermal energy, and other forms of energy.
    • Gravitational potential energy is not considered part of internal energy.
    • Calculating the absolute value of internal energy is impossible because it's challenging to determine the exact value of all energy types at a given time.
    • Internal energy is an extensive property, meaning it depends on the amount of matter in the system.
    • Internal energy is a state function, meaning its value depends solely on the system's current state, not the path it took to reach that state.

    Ideal Gas Internal Energy

    • For one mole of an ideal gas, internal energy (U) is equal to kinetic energy (KE) and is expressed as 3/2 * RT, where R is the ideal gas constant and T is the temperature.

    Thermodynamic Processes

    • Isobaric Process: A process occurring at constant pressure.
      • Pressure remains constant (ΔP = 0).
      • Work done (W) is calculated as W = PΔV, where P is the constant pressure and ΔV is the change in volume.
    • Isochoric Process: A process occurring at constant volume.
      • Volume remains constant (ΔV = 0).
      • Work done (W) is zero.
    • Isothermal Process: A process occurring at constant temperature.
      • Temperature remains constant (ΔT = 0).
      • For ideal gases, the change in internal energy (ΔU) is zero during an isothermal process.
      • For ideal gases with constant moles, the change in enthalpy (ΔH) is also zero.

    Work Done

    • Work done on a system is positive during compression.
    • Work done by a system is negative during expansion.
    • The unit of work is atmosphere-liter (atm × liter).
    • 1 atm × liter = 101.3 J = 24.23 cal.

    Heat

    • Heat (Q) is the energy transferred between bodies due to a temperature difference.
    • Heat absorbed by the system is represented as positive (+).
    • Heat evolved by the system is represented as negative (-).

    Systems and Surroundings

    • An isolated system does not exchange energy or matter with its surroundings.
    • An open system exchanges both energy and matter with its surroundings.
    • A closed system exchanges energy but not matter with its surroundings.

    Thermodynamic Properties

    • Intensive properties are independent of the system's mass, remain uniform throughout the system, and are non-additive.
    • Extensive properties depend on the system's mass, are additive, and their ratio can form an intensive property.
    • State functions are thermodynamic properties that depend only on the system's initial and final states, not the path taken between them.

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    Description

    Explore the concept of internal energy in thermodynamics, including its components such as potential and kinetic energy. This quiz covers key principles related to the internal energy of ideal gases and various thermodynamic processes. Test your understanding of how internal energy functions as a state property and its implications in different scenarios.

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