Thermodynamics

Date: 2015-10-07; view: 640.

Read the text and fulfill the tasks given in Comprehension check.

Thermodynamics is ascience of the relationship between heat, work, temperature, and energy. In broad terms, thermodynamics deals with the transfer of energy from one place to another and from one form to another. The key concept is that heat is a form of energy corresponding to a definite amount of mechanical work.

The principal laws of thermodynamics are:

The zeroth law of thermodynamics. When two systems are each in thermal equilibrium with a third system, the first two systems are in thermal equilibrium with each other. This property makes it meaningful to use thermometers as the “third system” and to define a temperature scale.

Ø The first law of thermodynamics, or the law of conservation of energy. The change in a system's internal energy is equal to the difference between heat added to the system from its surroundings and work done by the system on its surroundings.

Ø The second law of thermodynamics . The first law of thermodynamics asserts that energy must be conserved in any process involving the exchange of heat and work between a system and its surroundings. A machine that violated the first law would be called a perpetual motion machine of the first kind because it would manufacture its own energy out of nothing and thereby run forever. Such a machine would be impossible even in theory. However, this impossibility would not prevent the construction of a machine that could extract essentially limitless amounts of heat from its surroundings (earth, air, and sea) and convert it entirely into work. Although such a hypothetical machine would not violate conservation of energy, the total failure of inventors to build such a machine, known as a perpetual motion machine of the second kind, led to the discovery of the second law of thermodynamics. The second law of thermodynamics can be precisely stated in the following two forms, as originally formulated in the 19th century by the Scottish physicist William Thomson (Lord Kelvin) and the German physicist Rudolf Clausius, respectively. Heat does not flow spontaneously from a colder region to a hotter region, or, equivalently, heat at a given temperature cannot be converted entirely into work. Consequently, the entropy of a closed system, or heat energy per unit temperature, increases over time toward some maximum value. Thus, all closed systems tend toward an equilibrium state in which entropy is at a maximum and no energy is available to do useful work. This asymmetry between forward and backward processes gives rise to what is known as the “arrow of time.”

Ø The third law of thermodynamics. The entropy of a perfect crystal of an element in its most stable form tends to zero as the temperature approaches absolute zero. This allows an absolute scale for entropy to be established that, from a statistical point of view, determines the degree of randomness or disorder in a system.

Ø Although thermodynamics developed rapidly during the 19th century in response to the need to optimize the performance of steam engines, the sweeping generality of the laws of thermodynamics makes them applicable to all physical and biological systems. In particular, the laws of thermodynamics give a complete description of all changes in the energy state of any system and its ability to perform useful work on its surroundings.

Ludwig Eduard Boltzmann.

(born Feb. 20, 1844, Vienna, Austria—died Sept. 5, 1906, Duino, Italy),is a physicist whose greatest achievement was in the development of statistical mechanics, which explains and predicts how the properties of atoms (such as mass, charge, and structure) determine the visible properties of matter (such as viscosity, thermal conductivity, and diffusion).

After receiving his doctorate from the University of Vienna in 1866, Boltzmann held professorships in mathematics and physics at Vienna, Graz, Munich, and Leipzig.

In the 1870s Boltzmann published a series of papers in which he showed that the second law of thermodynamics, which concerns energy exchange, could be explained by applying the laws of mechanics and the theory of probability to the motions of the atoms. In so doing, he made clear that the second law is essentially statistical and that a system approaches a state of thermodynamic equilibrium (uniform energy distribution throughout) because equilibrium is overwhelmingly the most probable state of a material system. During these investigations Boltzmann worked out the general law for the distribution of energy among the various parts of a system at a specific temperature and derived the theorem of equipartition of energy (Maxwell-Boltzmann distribution law). This law states that the average amount of energy involved in each different direction of motion of an atom is the same. He derived an equation for the change of the distribution of energy among atoms due to atomic collisions and laid the foundations of statistical mechanics.Statistical mechanics, branch of physics that combines the principles and procedures of statistics with the laws of both classical and quantum mechanics, particularly with respect to the field of thermodynamics. It aims to predict and explain the measurable properties of macroscopic systems on the basis of the properties and behaviour of the microscopic constituents of those systems. Statistical mechanics interprets, for example, thermal energy as the energy of atomic particles in disordered states and temperature as a quantitative measure of how energy is shared among such particles. Statistical mechanics draws heavily on the laws of probability so that it does not concentrate on the behaviour of every individual particle in a macroscopic substance but on the average behaviour of a large number of particles of the same kind.

Boltzmann was also one of the first continental scientists to recognize the importance of the electromagnetic theory proposed by James Clerk Maxwell of England. Though his work on statistical mechanics was strongly attacked and long-misunderstood, his conclusions were finally supported by the discoveries in atomic physics that began shortly before 1900 and by recognition that fluctuation phenomena, such as Brownian motion (random movement of microscopic particles suspended in a fluid), could be explained only by statistical mechanics.

Comprehension check

9. Correct the sentences if it is necessary.

1. Thermodynamics is ascience of the relationship between only heat and work.

2. The principal law of thermodynamics is only the second one.

3. The zeroth law of thermodynamics states that when two systems are each in thermal equilibrium with a third system, the first two systems are in thermal equilibrium with each other. Thermal equilibrium isn't transitive.

4. The first law of thermodynamics, or the law of conservation of energy states that the change in a system's internal energy isn't equal to the difference between heat added to the system from its surroundings and work done by the system on its surroundings i.e. energy is conserved, it's form can't be converted.

5. The second law of thermodynamics asserts that energy must be conserved in any process involving the exchange of heat and work between a system and its surroundings.

6. A machine that violated the first law would be called a perpetual motion machine of the first kind because it would manufacture its own energy out of nothing and thereby run forever. Such a machine is possible .

7. The second law of thermodynamics can be precisely stated as heat flows spontaneously from a colder region to a hotter region, or, equivalently, heat at a given temperature can be converted entirely into work.

8. Consequently, the entropy of a closed system, or heat energy per unit temperature, decreases over time toward some maximum value.

9. The third law of thermodynamics states that the entropy of a perfect crystal of an element in its most unstable form tends to zero as the temperature approaches absolute zero.

10. Maxwell-Boltzmann distribution law states that the average amount of energy involved in each different direction of motion of an atom is the same.

11. Boltzmann derived an equation for the change of the distribution of energy among atoms due to atomic collisions and laid the foundations of quantum mechanics.

12. Statistical mechanics, branch of physics that combines the principles and procedures of statistics with the laws of both classical and quantum mechanics, particularly with respect to the field of thermodynamics.

10. Use the text to answer the following questions.

1. What is thermodynamics?

2. What does the zeroth law of thermodynamics state?

3. What does the first law of thermodynamics state?

4. How can the second law of thermodynamics be stated?

5. What is known as the “arrow of time”?

6. What does the third law of thermodynamics state?

7. What do the laws of thermodynamics give?

8. What is the greatest achievement of Boltzmann?

9. What does statistical mechanics explain?

10. What did Boltzmann work out?

11. What does this law state?

12.What does statistical mechanics combine?

11. Put the jumbled sentences in the logical order to sum up the contents of the text.

1.The key concept is that heat is a form of energy corresponding to a definite amount of mechanical work.

2. The first law of thermodynamics, or the law ofconservation of energy states that the change in a system's internal energy is equal to the difference between heat added to the system from its surroundings and work done by the system on its surroundings.

3. The third law of thermodynamics states thatthe entropy of a perfect crystal of an element in its most stable form tends to zero as the temperature approaches absolute zero.

4. During these investigations Boltzmann worked out the general law for the distribution of energy among the various parts of a system at a specific temperature and derived the theorem of equipartition of energy (Maxwell-Boltzmann distribution law).

5. Thus, all closed systems tend toward an equilibrium state in which entropy is at a maximum and no energy is available to do useful work.

6. Boltzmannis a physicist whose greatest achievement was in the development of statistical mechanics, which explains and predicts how the properties of atoms (such as mass, charge, and structure) determine the visible properties of matter (such as viscosity, thermal conductivity, and diffusion).

7. In broad terms, thermodynamics deals with the transfer of energy from one place to another and from one form to another.

8. The zeroth law of thermodynamics states thatwhen two systems are each in thermal equilibrium with a third system, the first two systems are in thermal equilibrium with each other.

9. Thermodynamics is ascience of the relationship between heat, work, temperature, and energy.

10. Consequently, the entropy of a closed system, or heat energy per unit temperature, increases over time toward some maximum value.

11. In the 1870s Boltzmann published a series of papers in which he showed that the second law of thermodynamics could be explained by applying the laws of mechanics and the theory of probability to the motions of the atoms.

12. Boltzmann was also one of the first continental scientists to recognize the importance of the electromagnetic theory proposed by James Clerk Maxwell of England.

13. The principal laws of thermodynamics are: the zeroth law of thermodynamics, the first law of thermodynamics, or the law of conservation of energy, the second law of thermodynamics, the third law of thermodynamics.

14. The second law of thermodynamics can be precisely stated in the following two forms, i.e. heat does not flow spontaneously from a colder region to a hotter region, or, equivalently, heat at a given temperature cannot be converted entirely into work.

15. In particular, the laws of thermodynamics give a complete description of all changes in the energy state of any system and its ability to perform useful work on its surroundings.

16. This law states that the average amount of energy involved in each different direction of motion of an atom is the same.

Follow–up activities

12. Choose the key sentences from the text “Thermodynamics” and write them down. Now work in pairs (or in groups). Ask your groupmate(s) to translate your Russian versions of the key sentences into English. Swap the roles.

ADDITIONAL TEXTS

Text A