2023-01-03T05:56:18+03:00[Europe/Moscow] en true <p><strong>Second law of thermodynamics </strong>from a systems view</p>, <p><strong>Second law of thermodynamics </strong>from an entropy view</p>, <p>Do NOT think of entropy as _____!</p>, <p><strong>Entropy</strong></p>, <p>Which of these systems has a higher entropy: 1 gram of water at 0°C, or 1 gram of ice at 0°C? Why?</p>, <p>Change in Entropy equation</p>, <p>Units of entropy</p>, <p>When energy is distributed into a system at a given temperature, its entropy _____. When energy is distributed out of a system at a given temperature, its entropy _____.</p>, <p>Notice that the second law states that energy will spontaneously disperse; it does not say that energy can never be _____. However, the concentration of energy will not _____.</p>, <p>_____ usually must be done to concentrate energy.</p>, <p>Remember that a system can be variably defined to include the entire universe; in fact, the second law ultimately claims that _____.</p>, <p>Change in entropy of the universe equation</p>, <p><strong>Reversible reaction</strong></p>, <p>How long would a reversible reaction take place over?</p>, <p>What is the change in entropy of a reversible process?</p>, <p>What is an example of a reversible process?</p>, <p>What is the difference between a reversible process in physics and one in chemistry (or anything else for that matter)?</p> flashcards
MCAT Physics and Math 3.4: Second Law of Thermodynamics and Entropy

MCAT Physics and Math 3.4: Second Law of Thermodynamics and Entropy

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  • Second law of thermodynamics from a systems view

    The second law of thermodynamics states that objects in thermal contact and not in thermal equilibrium will exchange heat energy such that the object with a higher temperature will give off heat energy to the object with a lower temperature until both objects have the same temperature at thermal equilibrium. As such, energy is constantly being dispersed.

  • Second law of thermodynamics from an entropy view

    The second law of thermodynamics states that energy spontaneously disperses from being localized to becoming spread out if it is not hindered from doing so.

  • Do NOT think of entropy as _____!

    disorder

  • Entropy

    Entropy is the measure of the spontaneous dispersal of energy at a specific temperature: how much energy is spread out, or how widely spread out energy becomes in a process.

  • Which of these systems has a higher entropy: 1 gram of water at 0°C, or 1 gram of ice at 0°C? Why?

    Water

    Water has more degrees of freedom, so essentially the kinetic energy is dispersed over a larger number of microstates. In this sense, water is less organized, or more disordered, than ice.

  • Change in Entropy equation

    ΔS is the change in entropyQrev is the heat that is gained or lost in a reversible processT is the temperature in kelvin

    ΔS is the change in entropy

    Qrev is the heat that is gained or lost in a reversible process

    T is the temperature in kelvin

  • Units of entropy

  • When energy is distributed into a system at a given temperature, its entropy _____. When energy is distributed out of a system at a given temperature, its entropy _____.

    increases

    decreases

  • Notice that the second law states that energy will spontaneously disperse; it does not say that energy can never be _____. However, the concentration of energy will not _____.

    localized or concentrated

    happen spontaneously in a closed system

  • _____ usually must be done to concentrate energy.

    work

  • Remember that a system can be variably defined to include the entire universe; in fact, the second law ultimately claims that _____.

    the entropy of the universe is increasing

  • Change in entropy of the universe equation

    ΔSuniverse = ΔSsystem + ΔSsurroundings > 0

  • Reversible reaction

    A hypothetical process whereby an infinitesimally small amount of heat is transferred from a system to its surroundings. Because the heat transfers are infinitesimally small, the system is always in equilibrium with the surroundings.

  • How long would a reversible reaction take place over?

    An infinite amount of time (thus making it impossible)

  • What is the change in entropy of a reversible process?

    ΔSuniverse = 0

  • What is an example of a reversible process?

    If we place a mixture of ice and liquid water into a thermostat that is also at 0°C and allow infinitesimal amounts of heat to be absorbed by the ice from the thermostat so that the ice melts to liquid water at 0°C and the thermostat remains at 0°C, then the increase in the entropy of the system (the water) will be exactly equal to the entropy decrease of the surroundings (the thermostat).

  • What is the difference between a reversible process in physics and one in chemistry (or anything else for that matter)?

    In physics, a reversible process is one which causes no net change in entropy of the universe. Freezing and unfreezing ice is clearly a reversible process on the chemical level, by by doing this over a reasonable time span the entropy of the universe increases, making it physically irreversible.