The kinetics of the thermal decomposition of sodium nitrate and of the reaction sodium nitrite
科技英语写作高级教程参考答案
V、练习参考答案练习1I、1、the（各项均为负。
)2、the; a （功率额定值是电阻器不会引起温度太大的上升而能安全地耗散的最大功率。
）3、an（这是均方根值伏特计。
）4、The; a（该设备的成功设计需要详细地了解性能指标。
）5、the; a; a（在氢原子的布尔模型中，一个电子绕一个质子以半径为R的圆周运转。
）6、the（电阻的单位是欧姆。
）7、an （这是一个h参数。
）8、/; /（图5－1画出了Oersted的实验。
）9、A; a; a（机器是能够传递力来完成某一确定目的的一种设备。
）10、/（水压机将在第14章加以考虑。
）11、the; the [/]（我们容易确定参数μ的值。
）12、/; the（根据式（2－1），我们得到以下的关系式。
）13、the; /（作者工作在位于阿林顿的得克萨斯大学。
）14、an（甚至当积分区间并不是无穷时，能够恰当地显示一个时函数的傅氏变换的仪器是多么重要啊！）II、1.Dr. Emmet graduated from Harvard University in 2001.2.Professor Li earned his Ph.D. degree in mechanical engineering from the Xi’anUniversity of Technology in 1988.3.Now we shall turn to the discussion of local area networks.4.The Bainbridge mass spectrometer is as important an instrument as the opticalspectrometer.5.How long a time [或How much time] is required to this experiment? The densityof a substance is its mass per unit volume.6.An increase in pressure always causes a decrease in volume.7.Fig. (2-5) shows what is expressed by Eq. (2-2).8.The unit of inductance is the henry.III、1.The UASMA protocol employs a unique frame structure.2.Finally, a broad stepped impedance transformer is designed by this method.3.Dynamic analysis and evaluation of the security of a proactive secret sharingsystem4.The approach can be applied to the one-dimensional potential barrier with anarbitrary profile.5.We propose a numerical method based on Newton’s iterative method.练习2I、1. This circuit consists of a battery, an inductor and a capacitor.2. Compute the electric fields at points a, b, and c.3. This satellite is used for communications between the United States and Great Britain, France and Italy.4. We assume that the antenna is vertical and that its loss is zero.5. Chapters 6, 7, and 8 deal with transmission lines.II、1. Its error is six parts in 1012.2. This computer stores four times more information than that one (does).3. The demand for this kind of equipment in the near future will be 20 times what it is.4. The voltage across this component is a few tenths of a volt.5. Now its internal pressure is one sixteenth what it was.III、1. This object is over five times heavier than that one is.2. Unless otherwise stated, it is assumed that silicon transistors are used and that I CBOcan be neglected.3. This circuit has the advantages of simple structure and easy adjustment.4. Figs. 1, 2, and 3 show this process in detail.5. For further information, consult references [3, 5, 9].练习3I、1. This new type of computer has many advantages over the general type.2. It is not difficult to solve this differential equation for the unknown quantity.3. Of these five new chapters, the first one deals with the basic principles of negative feedback.4. At this point/time, current differs in phase from voltage by 90o.5. By analyzing [By the analysis of] the parameters of the instrument, we can understand its performance.6. We will find out its average velocity over this distance.7. The science of electronics is too important in the world today.8. They solved this problem with great difficulty.II、1. For x＞1, there is no solution to this equation [this equation has no solution].2. Upon [On] substituting [substitution of] these values into [in] theequation, we obtained the following expression..3. This circuit is similar in operation to that of Fig. 1-10.4. This computer is very good in performance.5. These waves travel only in one direction.III、1. This paper presents a new method for the recognition of radar targets.2. The influence of the moving state of the target on the tracking accuracy of the EKF is great.3. Another comsat was launched on the morning of the 8th of October.4. V oltage is measured in volts.5. They will leave for Beijing to attend an international conference on mobile communication.6. Unless otherwise stated, it is assumed that silicon transistors are used and that I CBO can be neglected.7.练习4I、1. The force acts perpendicular to the surface of the table.2. The three coefficients here remains to be determined.3. The two equations below will be often (frequently) used in later chapters/in thechapters which follow.4. Here we use two metal balls 10 cm apart.5. The output remains/stays constant/unchanged/fixed/unaltered/the same.6. All the textbooks available discuss this problem.7. Accurate in operation and high in speed, computers have found wide applications.8. The answer to this problem looks correct.9. Two parallel wires a distance (of)δapart carry the current i.10. The problem now is how to measure the voltage across this component.11. These data will be sent to the computing center 2 kilometers away.12. Upon rearranging the equation above, we have [get, obtain] the following expression.13. These charges can interact with other charges present.14. Forces can be transmitted without contact, contrary to the common belief.15. This coefficient is typically 0.35.II、1. In this case, the input does not fall; nor [neither] does the output. […; the outputdoes not fall, either.]2. The resistance of a conductor depends not only on the material of which theconductor is made, but also on the size and temperature of the conductor.3. These scientists are very interested in this topic.4. This parameter can hardly be measured.5. In this laboratory, this instrument is more expensive than any other one/ any one else.6. The features of this device are small size and light weight.练习5I、1. This equation can be solved in either of the following two ways/the two ways which follow.2. This baseball will soon come to rest because of its interaction with the ground.3. Our choice of this coefficient as 1 is correct.4. From its definition as the ratio of a force to a length, we can see that k has the same unit as work (does).5. Our analysis of the machine is of great significance.6. This facilitates their use in circuit analysis.II、1. This police car is equipped with a receiver the size of a matchbox.2. Wires one hundredth the diameter of a silk thread are used to connect these components.3. We must water cool these equipments/devices.4. In the past, telephone calls were operator connected.5. AC can be changed/turned/converted/transformed/translated into/to DC, a process called/known as/referred to as rectification.6. A magnet attracts iron materials, a familiar phenomenon.7. Computers are capable of processing information, a process that previously could be accomplished only inside our heads.8. An instrument for measuring current, voltage, and resistance, the multimeter is widely used in electrical engineering.III、1. Secs. 1.1 and 1.2 will discuss several other problems.2. Problems are listed/given on pp. 1-5.3. In the equations above, all h’s are the hybrid parameters.4. The mass of the standard pound is equal to 0.4535924277 kilograms.5. All a’s and b’s in Eq. (5-1) are related to the impedance R o.6. We must take the effect of temperature on [upon] semiconductors into account.7. In this case, the variation of output with input is very small.8. This curve shows the dependence of distance on/upon speed.IV、1. None of them can solve this special type of differential equation.2. They do not know whether this material can stand so large a force or not.3. There are M polygons altogether, each of which has N vertexes.4. These two engineers are busy (in) designing a new kind of software.5. Iron is almost as good a conductor as aluminum.练习6I、1. This image, it will be noticed, is a real image.2. This technical problem, we hope, will be solved soon.3. 210 is approximately 1000, a fact that we think is very useful in the study of digital electronics.4. A resistor of say 100 ohms should be used here.II、1. None of those textbooks have/has mentioned this point.2. All of these x values cannot satisfy the equation.3. Neither of the two conditions is satisfied here.4. In the preceding/previous chapter, we discussed all kinds of force.5. This paper describes a new method for designing aircraft.6. By the end of the last century, the company had manufactured 5 000radars.7. Since 2008, this research institute has been developing a special kind of robot.III、1. In Section 1-2, the concept of force was introduced.2. As early as the 1940s, it was found that semiconductors are very useful.3. This result can also be arrived at in another way.4. At that time no use was made of this phenomenon/…, thisphenomenon was made no use of.5. This point will be dealt with in the next section.IV、1. This computer works much better than that one (does)/This computer is much better in performance than that one (is)..2. This computer requires many more components that that one (does).3. The distance of the moon from the earth is as great as 240 000 miles.4. The greater the resistance, the longer time it takes for the capacitor to reach its maximum voltage/…, the longer time is required for the capacitor to reach its maximum voltage.)5. The current as small as 0.1 A cannot produce enough heat.V、1. It is easy for us to determine the weight of the body. 或：We can determine the weight of the body easily.2. The two engineers are busy (in) designing a new type of computer.3. We find this concept very difficult to explain.4. None of these windows can withstand so large a force.5. Work equals [is equal to] force multiplied by/times distance.6. The results obtained agree with the experimental values. [… are in agreement with the experimental values.]练习7I、1. It will take a few months to design this kind of aircraft with the help of a computer.2. It is left as a problem to [for] the reader to show that this expression holds.3. The program to be executed is stored in this unit.4. This valley acts as the foundation on which to build the dam.5. In this laboratory there are many kinds of instrument for students to choose from.6. Let t0 equal/be equal to zero.7. The farther away the target (is), the longer time it takes for the echo to return.8. For the series to converge, x must be less than 1.9. We find this concept very difficult to understand.10. This method makes it much easier to detect targets.11. This factor will affect the ability of a computer to store information.12. We have to find out how large to make r so as for the series to converge.13. This is a pen to draw pictures with.14. Elasticity is the tendency of a body to return to its original condition after being deformed.15. Ordinary matter is said to be electrically neutral.16.This property makes it possible for metals to be made into any shape.17. This table is unfit for a student to do experiments on.18. Now we consider what path of integration to take.II、1. The sine law of the variation of light intensity with the cylinder diameter has been emphasized.2. Not only do temperature and light affect the conductivity, but the addition of impurities to semiconductors also makes it change greatly.3. Various satellites are frequently launched to obtain information about/on space.4. Our semiconductor industry came into being at the end of the 1950s.5. My colleagues and I would like to express our thanks to Professor W. Smith for his great help.练习8I、1. The amplifier amplifies the received signals.2. Moving molecules have kinetic energy.5. Fig. 1 – 3 shows the photo of a freely falling body.3. Speed equals distance divided by time.4. V oltage equals/is equal to current multiplied by resistance.5. The resistance of air increases with the increased/increasing/an increase in speed.6. A transformer is a device consisting of two or more coils wound on/round an iron core.7. It is necessary to find out the current flowing through this component.8. This book, properly used, will be of great help to the reader.9. Flowing through a circuit, the current will lose part of its energy.10. Given/Knowing time and speed, we/one can find out distance.11. Having studied this chapter, the student will understand/will have understood the principle of a computer.12. The speed of light being extremely great, we cannot measure it by ordinary methods.13. Several comsats were launched, all of them (being) high-altitude satellites.14. Called “the mother of all networks,”the Internet is a widely used international network.15. This force can be resolved into two components, one (being) horizontal and the other vertical.II、1.Let us construct/draw a circle with the origin as the center and of radius R.2.This parameter should be measured with E grounded.3. With no resistance in the circuit,the current will increase indefinitely.4. With this in view, we have written this book.5. This paper introduces a new design method/technique, with emphasis on its principle. III、1.Let us consider designing a computer.2.We refer to these components as being passive.3.This involves taking the Fourier transform.4.On/Upon rearranging the above equations, we obtain the following set ofequations.5.In using this equation, it does not matter which plane is considered as 1.IV、1. Given/Knowing resistance and current, one/we can determine/calculate voltage.2. The price of this instrument is high.3. A robot is a special kind of electronic device.4. The current starts flowing at the very moment we close the circuit.5. They have been designing a new type of computer these six months.练习9I、1. The problem was not solved until a completely different method was introduced.2. Nearly 100 years passed before the existence/presence of subatomic particles was confirmed by experiment/experimentally.3. The year this device was invented, World War II broke out.4. Small as they are, atoms are made up of still smaller particles.5. These two resistors should be selected/chosen so that the transistor can operate normally.6. The body is in such a state that it can do work.II、1. The relation that voltage is the product of current and resistance applies to all the dc circuits.2. The discovery that magnetism can produce current is extremely important in the field of electricity.3. An equation is an algebraic statement that two algebraic expressions are equal.4. There is evidence that no life exists on the moon.5. The question now arises whether the algorithm is of practical use.6. In this case there is no guarantee that the series is convergent.7. There is a growing/increasing awareness that these techniques/methods are very useful.8. One of/Among the most noteworthy achievements at that time was the realization that light consists of electromagnetic waves.9. This is due to/is caused by/results from the fact that there are many free electrons in conductors.10. Besides/In addition to the fact that the properties of the material should be included in the analytical model, we must take other factors into account.III、1.These features make it difficult for electronic counter-measure systemsto intercept, analyze and jam this kind of signal.2. The existence of and the ability to control these phenomena make those devicespossible.3. The variation of/in the number of the filter’s teeth has a greater effect on the performance of its passband than the variation of/in its dimensions.4. Scalar detection will result in the loss of some phase information.5. Fig. 6 shows the schematic diagram of measuring scatter parameters by the natural parameter transformation method.练习10I、1. Now it remains to be determined when the series converges.2. It is clear from Dubamel’s Theorem that this limit exists.3. It follows from Maxwell’s hypothesis that whenever there is a change in an electric field, a magnetic field is produced.4. It does not matter whether the magnet is moved in this case.5. Temperature determines in what direction the transfer of heat will take place.6. It is now a well-known fact that all matter consists of tiny particles.II、1. What a generator does is (to) change mechanical energy into electrical energy.2. What this chapter describes/What is described in this chapter is of great importance.3. Matter is what can occupy space.4. What we have discovered in this experiment is the entirely new realm of electrical phenomenon.5. This direction is opposite to what has been assumed.6. Magnitude, direction, and place of application are what we call the three elements of a force.7. These numbers constitute what is known as the real number system.8. In what follows, we shall acquaint ourselves with some basic concepts.III、1. An x-band wave-guide test system is shown in Fig.7. [或：Fig. 7 shows …].2. This method lowers the requirement for the hardware of a sample network.3. On the basis of the above analysis of the decomposition of the polynomial, a novel configuration results. [或：The above analysis of the decomposition of the polynomial results in a novel configuration.]4. Finally, an analysis of packet loss probability is made by computer simulation.5. The sparse ratio of the resulting impedance matrix is as high as 40%.练习11I、1. The meter (that/which) we use to measure the voltage across a resistor is called a voltmeter.2. Computers are the most efficient assistants (that) man has ever had.3. Now this disease is no longer the serious problem (that) it once was.4. Radar can measure the time (that) it takes for the radio echo to return.5. We must calculate the distance (that/through which) the body is lifted.6. The direction (that/in which) a body moves is also very important.7. The number of times (that/by which) this particle vibrates per/a second is called/termed/named/known as/spoken of as/referred to as frequency.8. We equate these two ratios, from which the simplest formula follows/results.9. It is necessary to determine the time when/that/at which the y-component has decreased to zero.10.. The curve the y-coordinate of each point on which is zero is just the x-axis.II、1. The point at which the circle cuts the axis of reals is where α= ω.2. The force of gravity means the force with which the earth attracts a body.3. The surface of a picture tube upon which the electrons produce the picture is called the screen.4. The author would like to express thanks to the editors of the series of which this book is a part/to which this book belongs.5. This is a parallelogram of which the two given vectors are/form sides.6. The pressure is equal to the total force divided by the area over which it is exerted.7. The two elements of which water consists are hydrogen and oxygen.8. This depends on the efficiency with which electrons are produced.9. These two laws are the foundation on which all other laws are built.10. The temperature at which water freezes is generally 0o C.III、1. As the title indicates, this chapter will discuss nonlinear equations.2. As the name shows, a fluid is a substance which flows readily.3. This single force produces the same effect as is produced by those forces together.4. Now we are able to solve such differential equations as occur in physics.5. This function can be accomplished by using the full adder as was described in the previous section.6. These concepts enable us to understand a wide range of phenomena in electrostatics, or “static electricity,” as it is called.7. This current is, as predicted, very small,8. First let us consider the simplest circuit as shown on page 2.IV、1. This is a slightly higher value than we predicted.2. This reactor can produce more fuel than it consumes.3. Let us consider the case when the torque is zero.4. We must determine the values of currents and voltages after the switch closes.5. During the ten years since this book was first published, significant changes have taken place/have been seen in metal-making.V、1. Even in this case these protocols can provide a limited number of users with the acceptable quality of voice service.2. This paper presents a method for an 8098 microcontroller to series-communicate witha 386 personal computer.3. The effect of equalizer parameters on equalization performance is analyzed in detail.[A detailed analysis is made of the effect of equalization parameters on equalization performance.]4. Each receiver channel in Fig. 1 contains an RF amplifier, a mixer, an IF amplifier, an A/D converter, etc.（注意：句尾的句号与缩略词“etc.”的黑点重合在一起了）5. The larger the abnormal extent (is), the larger is the residual mismatch, with the curve going up.练习12I、1. be grounded;2. be carried;3. be raised;4. be;5. not try;6. be; be satisfied;7. be;8. be; was; have; 10. were concentrated; 11. had been; 12. were moving; 13. is going to rain; 14. be; 15. leakII、1. Should anything abnormal happen, switch/turn off the power supply at once/immediately.2. Had electronic computers not been used, it would have taken them a long time to solve this problem.3. It is very important that all solutions (should) be checked in the original equation.4. It is suggested that this design (should) be modified at once.5. Without semiconductors, satellite communications would be impossible.6. We could also have used Theorem (6) to derive the result.7. The requirement that energy (should) be conserved must be satisfied.8. Everything here, be it a component or a device, is home-made.III、1. It was this scientist who/that discovered this phenomenon a century ago.2. Tungsten is the very metal used in electric lamps.3. The speed with which sound waves move through a medium does depend on the properties of the medium.4. It is not clear yet under what conditions it is that this formula can be used.5. This property we call inertia.IV、1. The author is engaged in the teaching of and the research on computer vision, and image processing and recognition.2. Let P and Q be two Boolean permutations of the same order, and then their composition is a new Boolean permutation.3. Three algorithms are presented, which can remarkably reduce the time to raise the pen, thus raising the drawing efficiency.4. What this paper describes is of great interest to communications engineers.5. The minimum entropy technique for estimating the Doppler frequency rate is presented, which has the advantages over the classical techniques of high accuracy and a small amount of computation.练习13II、1. By electromagnetic force is meant the potential difference across the battery when there is no flow of current.2. In the table below/which follows are listed various parameters of familiar computers.3. An element cannot be decomposed, nor can it be broken up by chemical methods.4. Only when x = 8, does this equation hold/apply.5. Of particular importance/Especially important are the two concepts which follow.6. Such a set we call the mathematical system.7. Rarely does one know this function with precision.8. This interrelationship between electric and magnetic fields makes possible such things as the electromagnet and the electric motor.9. Not until 1818 was the diffraction of light interpreted/explained.10. By no means do electrons move from the positive terminal to the negative terminal ina wire.II、1. The effect of air resistance is discussed in Chapter 15, and the decrease in acceleration with altitude in Chapter 17.2. It is necessary to determine the charge on and the voltage across this capacitor.3. In this case, no standard is needed, but only a numerical convention.4. This voltage is greater than or equal to 0.4 volt.5. The cathode, when heated, emits electrons.6. Every body, whether accelerated or not, is considered (to be) in equilibrium.7. If necessary, the wire will be covered with some insulation.8. The transistor has its materials arranged p-n-p, hence the name pnp transistor.III、1. An initial analysis is made of the performance of the device.2. The magnetic field is the space around a magnet occupied by the magnetic lines of force.3. This leads to the battery voltage in the model of 500 mV.4. This graph shows the variation with frequency of the resistance of the resistor.5. This is responsible for the direct return to the atmosphere of more than half the water that falls on the land.6. The question now arises how these unknowns can be determined.7. It is necessary to determine the effect on the device of changing the ambient temperature.8. The assumption has been made that the pressure always remains constant during the test.IV、1. The simulation results show that both the schemes are easy to implement.2. The model and algorithm proposed in this paper are to a certain degree/extent superior in performance to the conventional BP algorithm.3. A new technique for estimating the frequency deviation is proposed which gives a high accuracy and requires a small amount of computation.4. Improvement of the accuracy of range alignment in ISAR imaging (by) using the super resolution technique5. Research on and the realization of DTMF in a Cipher Coder6. Analysis of the ability of a quartz flexibility accelerometer to resist bad environment。
英文版大学物理-第七章
translational kinetic energy of the molecules of a
Chapter 7 The Kinetic Theory of Gases
7-1 Temperature and Thermal Equilibrium 7-2 Thermodynamic Variables and the
Equation of State 7-3 Pressure and Molecular Motion 7-4 The Microscopic Interpretation of
R = 8.31 J/molK. (the universal gas constant)
An alternative form of ideal gas law:
pV m RT N RT
M
NA
The Boltzmann’s constant
k R 1.38 1023 J / K
NA
pV NkT ,
We get 2 ( 1 mv2 ) kT ,
32
The average translational
K 1 mv2 3 kT kinetic energy of molecules in
2
2
an ideal gas directly depends
only on the temperature, not on
A sample of gas consists of many identical molecules. The molecules are very far apart in comparison to
their size; The direction of motion of any molecule is random; The molecules are treated as if they were hard
中科院博士研究生英语精读教材翻译及原文整理解读
第1课知识的悖论The Paradox of KnowledgeThe greatest achievement of humankind in its long evolution from ancient hominoid ancestors to its present status is the acquisition and accumulation of a vast body of knowledge about itself, the world, and the universe. The products of this knowledge are all those things that, in the aggregate, we call "civilization," including language, science, literature, art, all the physical mechanisms, instruments, and structures we use, and the physical infrastructures on which society relies. Most of us assume that in modern society knowledge of all kinds is continually increasing and the aggregation of new information into the corpus of our social or collective knowledge is steadily reducing the area of ignorance about ourselves, the world, and the universe. But continuing reminders of the numerous areas of our present ignorance invite a critical analysis of this assumption.In the popular view, intellectual evolution is similar to, although much more rapid than, somatic evolution. Biological evolution is often described by the statement that "ontogeny recapitulates phylogeny"--meaning that the individual embryo, in its development from a fertilized ovum into a human baby, passes through successive stages in which it resembles ancestral forms of the human species. The popular view is that humankind has progressed from a state of innocent ignorance, comparable to that of an infant, and gradually has acquired more and more knowledge, much as a child learns in passing through the several grades of the educational system. Implicit in this view is an assumption that phylogeny resembles ontogeny, so that there will ultimately be a stage in which the accumulation of knowledge is essentially complete, at least in specific fields, as if society had graduated with all the advanced degrees that signify mastery of important subjects.Such views have, in fact, been expressed by some eminent scientists. In 1894 the great American physicist Albert Michelson said in a talk at the University of Chicago:While it is never safe to affirm that the future of Physical Science has no marvels in store even more astonishing than those of the past, it seems probable that most of the grand underlying principles have been firmly established and that further advances are to be sought chiefly in the rigorous application of these principles to all the phenomena which come under our notice .... The future truths of Physical Science ate to be looked for in the sixth place of decimals.In the century since Michelson's talk, scientists have discovered much more than the refinement of measurements in the sixth decimal place, and none is willing to make a similar statement today. However, many still cling to the notion that such a state of knowledge remains a possibility to be attained sooner or later. Stephen Hawking, thegreat English scientist, in his immensely popular book A Brief History of Time (1988), concludes with the speculation that we may "discover a complete theory" that "would be the ultimate triumph of human reason--for then we would know the mind of God." Paul Davies, an Australian physicist, echoes that view by suggesting that the human mind may be able to grasp some of the secrets encompassed by the title of his book The Mind of God (1992). Other contemporary scientists write of "theories of everything," meaning theories that explain all observable physical phenomena, and Nobel Laureate Steven Weinberg, one of the founders of the current standard model of physical theory, writes of his Dreams of a Final Theory (1992).Despite the eminence and obvious yearning of these and many other contemporary scientists, there is nothing in the history of science to suggest that any addition of data or theories to the body of scientific knowledge will ever provide answers to all questions in any field. On the contrary, the history of science indicates that increasing knowledge brings awareness of new areas of ignorance and of new questions to be answered.Astronomy is the most ancient of the sciences, and its development is a model of other fields of knowledge. People have been observing the stars and other celestial bodies since the dawn of recorded history. As early as 3000 B.C. the Babylonians recognized a number of the constellations. In the sixth century B.C., Pythagoras proposed the notion of a spherical Earth and of a universe with objects in it chat moved in accordance with natural laws. Later Greek philosophers taught that the sky was a hollow globe surrounding the Earth, that it was supported on an axis running through the Earth, and chat stars were inlaid on its inner surface, which rotated westward daily. In the second century A.D., Ptolemy propounded a theory of a geocentric (Earth-centered) universe in which the sun, planets, and stars moved in circular orbits of cycles and epicycles around the Earth, although the Earth was not at the precise center of these orbits. While somewhat awkward, the Ptolemaic system could produce reasonably reliable predictions of planetary positions, which were, however, good for only a few years and which developed substantial discrepancies from actual observations over a long period of time. Nevertheless, since there was no evidence then apparent to astronomers that the Earth itself moves, the Ptolemaic system remained unchallenged for more than 13 centuries.In the sixteenth century Nocolaus Copernicus, who is said to have mastered all the knowledge of his day in mathematics, astronomy, medicine, and theology, became dissatisfied with the Ptolemaic system. He found that a heliocentric system was both mathematically possible and aesthetically more pleasing, and wrote a full exposition of his hypothesis, which was not published until 1543, shortly after his death. Early inthe seventeenth century, Johannes Kepler became imperial mathematician of the Holy Roman Empire upon the death of Tycho Brahe, and he acquired a collection of meticulous naked-eye observations of the positions of celestial bodies chat had been made by Brahe. On the basis of these data, Kepler calculated that both Ptolemy and Copernicus were in error in assuming chat planets traveled in circular orbits, and in 1609 he published a book demonstrating mathematically chat the planets travel around the sun in elliptical orbits. Kepler's laws of planetary motion are still regarded as basically valid.In the first decade of the seventeenth century Galileo Galilei learned of the invention of the telescope and began to build such instruments, becoming the first person to use a telescope for astronomical observations, and thus discovering craters on the moon, phases of Venus, and the satellites of Jupiter. His observations convinced him of the validity of the Copernican system and resulted in the well-known conflict between Galileo and church authorities. In January 1642 Galileo died, and in December of chat year Isaac Newton was born. Modern science derives largely from the work of these two men.Newton's contributions to science are numerous. He laid the foundations for modem physical optics, formulated the basic laws of motion and the law of universal gravitation, and devised the infinitesimal calculus. Newton's laws of motion and gravitation are still used for calculations of such matters as trajectories of spacecraft and satellites and orbits of planets. In 1846, relying on such calculations as a guide to observation, astronomers discovered the planet Neptune.While calculations based on Newton's laws are accurate, they are dismayingly complex when three or more bodies are involved. In 1915, Einstein announced his theory of general relativity, which led to a set of differential equations for planetary orbits identical to those based on Newtonian calculations, except for those relating to the planet Mercury. The elliptical orbit of Mercury rotates through the years, but so slowly that the change of position is less than one minute of arc each century. The equations of general relativity precisely accounted for this precession; Newtonian equations did not.Einstein's equations also explained the red shift in the light from distant stars and the deflection of starlight as it passed near the sun. However, Einstein assumed chat the universe was static, and, in order to permit a meaningful solution to the equations of relativity, in 1917 he added another term, called a "cosmological constant," to the equations. Although the existence and significance of a cosmological constant is still being debated, Einstein later declared chat this was a major mistake, as Edwin Hubble established in the 1920s chat the universe is expanding and galaxies are receding fromone another at a speed proportionate to their distance.Another important development in astronomy grew out of Newton's experimentation in optics, beginning with his demonstration chat sunlight could be broken up by a prism into a spectrum of different colors, which led to the science of spectroscopy. In the twentieth century, spectroscopy was applied to astronomy to gun information about the chemical and physical condition of celestial bodies chat was not disclosed by visual observation. In the 1920s, precise photographic photometry was introduced to astronomy and quantitative spectrochemical analysis became common. Also during the 1920s, scientists like Heisenberg, de Broglie, Schrodinger, and Dirac developed quantum mechanics, a branch of physics dealing with subatomic particles of matter and quanta of energy. Astronomers began to recognize that the properties of celestial bodies, including planets, could be well understood only in terms of physics, and the field began to be referred to as "astrophysics."These developments created an explosive expansion in our knowledge of astronomy. During the first five thousand years or more of observing the heavens, observation was confined to the narrow band of visible light. In the last half of this century astronomical observations have been made across the spectrum of electromagnetic radiation, including radio waves, infrared, ultraviolet, X-rays, and gamma rays, and from satellites beyond the atmosphere. It is no exaggeration to say chat since the end of World War II more astronomical data have been gathered than during all of the thousands of years of preceding human history.However, despite all improvements in instrumentation, increasing sophistication of analysis and calculation augmented by the massive power of computers, and the huge aggregation of data, or knowledge, we still cannot predict future movements of planets and other elements of even the solar system with a high degree of certainty. Ivars Peterson, a highly trained science writer and an editor of Science News, writes in his book Newton's Clock (1993) that a surprisingly subtle chaos pervades the solar system. He states:In one way or another the problem of the solar system's stability has fascinated and tormented asrtonomers and mathematicians for more than 200 years. Somewhat to the embarrassment of contemporary experts, it remains one of the most perplexing, unsolved issues in celestial mechanics. Each step toward resolving this and related questions has only exposed additional uncertainties and even deeper mysteries.Similar problems pervade astronomy. The two major theories of cosmology, general relativity and quantum mechanics, cannot be stated in the same mathematical language, and thus are inconsistent with one another, as the Ptolemaic and Copernicantheories were in the sixteenth century, although both contemporary theories continue to be used, but for different calculations. Oxford mathematician Roger Penrose, in The Emperors New Mind (1989), contends that this inconsistency requires a change in quantum theory to provide a new theory he calls "correct quantum gravity."Furthermore, the observations astronomers make with new technologies disclose a total mass in the universe that is less than about 10 percent of the total mass that mathematical calculations require the universe to contain on the basis of its observed rate of expansion. If the universe contains no more mass than we have been able to observe directly, then according to all current theories it should have expanded in the past, and be expanding now, much more rapidly than the rate actually observed. It is therefore believed that 90 percent or more of the mass in the universe is some sort of "dark matter" that has not yet been observed and the nature of which is unknown. Current theories favor either WIMPs (weakly interacting massive particles) or MACHOs (massive compact halo objects). Other similar mysteries abound and increase in number as our ability to observe improves.The progress of biological and life sciences has been similar to that of the physical sciences, except that it has occurred several centuries later. The theory of biological evolution first came to the attention of scientists with the publication of Darwin's Origin of Species in 1859. But Darwin lacked any explanation of the causes of variation and inheritance of characteristics. These were provided by Gregor Mendel, who laid the mathematical foundation of genetics with the publication of papers in 1865 and 1866.Medicine, according to Lewis Thomas, is the youngest science, having become truly scientific only in the 1930s. Recent and ongoing research has created uncertainty about even such basic concepts as when and how life begins and when death occurs, and we are spending billions in an attempt to learn how much it may be possible to know about human genetics. Modern medicine has demonstrably improved both our life expectancies and our health, and further improvements continue to be made as research progresses. But new questions arise even more rapidly than our research resources grow, as the host of problems related to the Human Genome Project illustrates.From even such an abbreviated and incomplete survey of science as this, it appears that increasing knowledge does not result in a commensurate decrease in ignorance, but, on the contrary, exposes new lacunae in our comprehension and confronts us with unforeseen questions disclosing areas of ignorance of which we were not previously aware.Thus the concept of science as an expanding body of knowledge that will eventually encompass or dispel all significant areas of ignorance is an illusion. Scientists and philosophers are now observing that it is naive to regard science as a process that begins with observations that are organized into theories and are then subsequently tested by experiments. The late Karl Popper, a leading philosopher of science, wrote in The Growth of Scientific Knowledge (1960) chat science starts from problems, not from observations, and chat every worthwhile new theory raises new problems. Thus there is no danger that science will come to an end because it has completed its task, clanks to the "infinity of our ignorance."At least since Thomas Kuhn published The Structure of Scientific Revolutions (1962), it has been generally recognized that observations are the result of theories (called paradigms by Kuhn and other philosophers), for without theories of relevance and irrelevance there would be no basis for determining what observations to make. Since no one can know everything, to be fully informed on any subject (a claim sometimes made by those in authority) is simply to reach a judgment that additional data are not important enough to be worth the trouble of securing or considering.To carry the analysis another step, it must be recognized that theories are the result of questions and questions are the product of perceived ignorance. Thus it is chat ignorance gives rise to inquiry chat produces knowledge, which, in turn, discloses new areas of ignorance. This is the paradox of knowledge: As knowledge increases so does ignorance, and ignorance may increase more than its related knowledge.My own metaphor to illustrate the relationship of knowledge and ignorance is based on a line from Matthew Arnold: "For we are here as on a darkling plain...." The dark chat surrounds us, chat, indeed, envelops our world, is ignorance. Knowledge is the illumination shed by whatever candles (or more technologically advanced light sources) we can provide. As we light more and more figurative candles, the area of illumination enlarges; but the area beyond illumination increases geometrically. We know chat there is much we don't know; but we cannot know how much there is chat we don't know. Thus knowledge is finite, but ignorance is infinite, and the finite cannot ever encompass the infinite.This is a revised version of an article originally published in COSMOS 1994. Copyright 1995 by Lee Loevinger.Lee Loevinger is a Washington lawyer and former assistant attorney general of the United States who writes frequently for scientific c publications. He has participated for many years as a member, co-chair, or liaison with the National Conference of Lawyers and Scientists, and he is a founder and former chair of the Science andTechnology Section of the American Bar Association. Office address: Hogan and Hartson, 555 Thirteenth St. NW, Washington, DC 20004.人类从古类人猿进化到当前的状态这个长久的进化过程中的最大成就是有关于人类自身、世界以及宇宙众多知识的获得和积聚。
fundamentals of thermoelectricity oxford 2015
fundamentals of thermoelectricityoxford 2015The fundamentals of thermoelectricity, as discussed in the Oxford 2015 book, are crucial for understanding the conversion of heat into electrical energy. This field combines principles from thermodynamics, solid-state physics, and materials science to explore the behavior and performance of thermoelectric devices. Thermoelectricity has gained significance in recent years due to its potential application in waste heat recovery, portable power generation, and energy-efficient cooling systems. Let's dive into some key concepts covered in this book.Thermoelectric phenomena arise from a temperature gradient across a material or device. The underlying principle is the Seebeck effect, which describes the generation of an electric voltage when there is a temperature difference between two points in a conductor or semiconductor. This voltage is proportional to the gradient in temperature and depends on the material properties.热电现象是在材料或器件中存在温度梯度时产生的。
γ丁内酯气相胺解反应及其动力学研究
!易国斌，崔英德，康正，余林，郭建维，邓志城，廖列文（广东工业大学轻工化工学院，广东广州510006）摘要：研究了!-丁内酯与乙醇胺在改性Y 型分子筛上气相反应合成!-羟乙基吡咯烷酮（N H P）的情况，考察了分子筛组成、反应温度等对催化性能的影响。
结果表明，CuREY 具有较高的活性与稳定性，合适的反应温度为260—280 C 。
采用最小二乘法研究了反应的表观动力学，得到双曲线速率方程，计算了相关动力学参数，用Arr hen i us公式计算了近似的反应活化能与!-丁内酯、乙醇胺的吸附活化能分别为49. 28、-29. 84、-21. 53 k J/ mo i，表明活性物种之间的反应为决速步骤。
回归相关系数表明，双曲线动力学方程与反应能较好地吻合。
关键词：Y 型分子筛；!-丁内酯；!-羟乙基吡咯烷酮；动力学中图分类号：0 643 文献标识码：A 文章编号：1005-9954（2006）05-0028-05S t ud i es on gas phase a m i n a t i o n r e ac t i o n of!-bu t y r o l ac t o n e and i t s k i n e t i c sYI Gu o-b i n，CU I Y i n g-d e，K ANG Zh e n g，YU Lin，GUO J i a n-w e i，DENG Zh i-c h e n g，L I AO Li e-w e n（F a cu i t y of Ch e m i c a i E n g i n ee r i n g and L i g h t I ndu s tr y，Gu a n g d o n g Un i v e r s i t y of T e chn o i og y，Guangzhou 510006，Guangdong P r o v i nc e，Ch i n a）Ab s t r ac t：G as phase r ea c t i o n of !-bu t y r o i a c t o n e and e t h a n o i a m i n e to produc e !-hy d r o xy e t hy i py rr o ii d o n e（NHP）on m o d i f i e d Y Z eo ii t es w as s t ud i e d.I n f i u e nc es of some factors such as c a t a i y s t c o mp os i t i o n and r ea c t i o n temperature on c a t a i y t i c p r o p e rt i es were d i s c u ss e d.The r es u i t s show that CuREY has c o mp a r a t i v e i y h i g h c a t a i y t i c a c t i v i t y，s t a b iii t y，and o p t i m a i r ea c t i o n temperature i s 260-280 C . Apparent k i n e t i c s of the r ea c t i o n w as i nv es t i ga t e d w i t h i eas t-s gu a r es method and hy p e r b o ii c rate e gu a t i o n was represented. K i n e t i c parameters w e r e c a i c u i a t e d. A c t i v a t i o n energy for the r ea c t i o n of the a d s o r p t i v e m o i e c u i es，a d s o r p t i o n a c t i v a t i o n energy o f !-bu t y r o i a c t o n e and e t h a n o i a m i n e c a i c u i a t e d through the Arr h e n i u s e gu a t i o n are a pp r o x i m a t e i y49. 28，- 29. 84 and - 21. 53 k J/ m o i r es p e c t i v e i y，wh i ch i nd i c a t es that the r ea c t i o n of a d s o r p t i v e m o i e c u i es i s r a t e-d e t e r m i n i n g step. The c o rr e i a t i o n c oe ff i c i e n t shows that o b t a i n e d hy p e r b o ii c k i n e t i c e gu a t i o n i s f i tt i n g w e ii w i t h the r ea c t i o n.K e y w o r d s：Y-z eo ii t e；!-bu t y r o i a c t o n e；!-hy d r o xy i py rr o ii d o n e；k i n e t i c s含0 杂环化合物的取代反应是一类重要反应，由此可以合成许多中间体。
The kinetic theory describes the ___1____ or particles in ：动力学理论描述的___1____或颗粒
Chemistry—Ch. 13Use your textbook and/or the power point to complete the statements.13.1The Nature of Gases1.The energy an object has because of its motion is called ___________________.2.According to the kinetic theory, all matter consists of tiny particles that are in constantmotion. The fundamental assumptions about gases are (key concepts p. 385):a)b)c)3.Gas pressure is ____________________________________________________;atmospheric pressure results from _____________________________________.4.The SI unit of pressure is the _____________. At STP, standard pressure is __________,______________, or ___________.5. At absolute zero (0 K or –273 C), particles ___________________________________________________________________________________________________. 13.2The Nature of Liquids6.Based on the kinetic theory, a key difference between gases and liquids is:7.The conversion of a liquid to a gas or vapor is ____________________; when it occurs atthe surface of a liquid it is called ______________________.8.Copy key concept on p. 391: During evaporation,9.Copy key concept on p. 392: In a system at constant vapor pressure,10.The temperature at which the vapor pressure of the liquid is just equal to the externalpressure on the liquid is the _______________________.11.Normal boiling point is ______________________________________________.12. Copy the information from figure 13.8 on p. 39413.3 The Nature of Solids13.Write the information in the first paragraph under “A Model for Solids” on p. 396.13. 4 Changes of State14.A phase diagram gives __________________________________________________________________________________________________________________.15.The triple point ____________________________________________________.16.Draw the phase diagram of water on p. 403 and explain.17.from power point: copy the kinetic theory information (Hein-Arena version)18. from power point: draw the chart for physical phasesChemistry—Ch. 13 textbook problemsp. 406 (26-30, 38-39, 49, 54-56, 65, 70)26. What is meant by an elastic collision?27. Which of these statements are characteristic of matter in the gaseous state?a)gases fill their containers completelyb)gases exert pressurec)gases have massd)the pressure of a gas is independent of its temperaturee)gases are compressiblef)the distances between particles in a gas are relatively large28. List the various units used to measure pressure and identify the SI unit (show equivalence).29. Change 1656 kPa to atm.30. Convert 190 mm Hg to the following.a.kilopascalsb.atmospheres of pressure38. Describe what is happening at the molecular level when a dynamic equilibrium occurs.39. Explain why increasing the temperature of a liquid increases its rate of evaporation.49. Explain why a liquid stays at a constant temperature while it is boiling?54. The table gives the vapor pressure of isopropyl alcohol at various temperatures. Graph the data. Use aa.What is the estimated normal boiling point of isopropyl alcohol?—show on graphb.What is the boiling point of isopropyl alcohol when the external pressure is increased to twicestandard pressure?—show on graph55.In a series of liquids, as the intermolecular forces of attraction strengthen, would you expect thevapor pressure to increase or decrease? Explain.56.Predict the physical state of each of these substances at the indicated temperature. Use the meltingpoint and boiling point data from the table below.a.phenol at 99o Cb.ammonia at –25o Cc.methanol in an ice-water bathd.methanol in a boiling-water bathe.ammonia at –100o Cf.phenol at 25o C65. How does perspiration help cool your body on a hot day?70. Why are pressure cookers recommended for cooking at high-altitude?Reading Phase Diagrams1. What variables are plotted on a phase diagram?2. How many phases of water are represented in its phase diagram? What are they?e the phase diagram for water to complete the following table.Temperature ( C) Pressure (atm) Phase200 1-2 1150 100-2 0.00130 0.81 Liquid100.00 Vapor4.What phases of water coexist at each point along the curve AC?5.What two-phase changes occur at each point along curve AB in the phase diagram forwater?6.Look at the phase diagram for carbon dioxide. Above which pressure and temperature iscarbon dioxide unable to exist as a liquid?7.At which pressure and temperature do the solid, liquid, and gaseous phases of carbondioxide coexist?。
温度对微孔发泡PP和HDPE材料冲击性能的影响 (1)
的一种新型的热塑性高分子材料。微孔发泡材 料具有密度低、 较高的冲击强度、 比强度、 抗疲 劳强度和热稳定性 等优异性能。大量实验 表 明, 微孔对聚合物材料的常温冲击性能常常起 增韧的作用 。 Waldman 在测量微孔发泡 PS 的冲击韧性时, 发现 其缺口 Charpy 冲击韧 性和落重冲击韧性结论相反。微孔对聚合物材 料冲击性能影响的研究通常在常温下测试, 缺 乏不同实验条件下变形断裂规律及机制的系统 研究 , 且微孔对聚合物材料冲击性能的影响也 存在矛盾的结论。本文以 PP、 HDPE 为对象 , 在较宽的温度范围内系统测试了不同实验温度 下微孔发泡和未发泡 PP 、 H DPE 的 Izod 缺口冲 击强度, 并结合冲击断口形貌特征系统观察, 研 究了实验温度对微孔发泡 PP、 H DPE 材料冲击 强度 及 断 裂 机 制 的 影 响, 为 微 孔 发 泡 PP、 HDPE 的研究和应用提供了理论依据。
大的影响, 微孔的引入又使温度对 Izod 缺口冲 击强度的影响关系出现了新的变化。从 Fig. 1 、 F ig. 2 中可以看出 , 微孔发泡 PP、 HDPE, 以及 对应未发泡 PP 、 H DPE 都随实验温度的降低其 Izod 缺 口 冲 击 强 度 值 下 降。 对 于 P P, 在 - 57 ~ 63 范围内 , 微发泡高于未发泡 P P 的 Izod 缺口冲击强度 , 随着温度的变化, 微发 泡和未发泡 PP 的 Izod 缺口冲击强度的变化趋 势相似。如果将未发泡 PP 的曲线整体向上移 动至与微发泡 PP 的直线部分重合 ( Fig. 1 中虚 线部分 ) , 则可得出 , 微发泡 P P 具有优越的低 温冲 击性 能; 有 较低 的韧 脆转 变温 度。 对于 HDPE, 实验温度范围内, 都在 - 53 度高于 - 35 存在 Izod 缺口冲击强度值随温度变化规律的突变 , 且温 , 微孔发泡 H DPE 的 Izod 缺口 后, 冲击强度比未发泡的低, 温度低于 - 35
科技英语参考答案
科技英语参考答案Unit One科学的演进科学的起源1．通过旧石器时期人们涂写在洞穴墙壁上的图案，在骨头或石头上所刻的计数记录，以及新石器时期文明存留下来的人工制品，人类对知识系统化方面的努力可以追溯到史前期。
远古科学研究的最古老的文字记录来自美索不达米亚文化。
很多的天文观测，化学物质，疾病症状以及很多不同的数学算表以楔形文字的形式刻在黏土块上。
其他一些可追溯到2000B.C.的黏土块表明，巴比伦尼亚人对毕达哥拉斯定理已有所了解，已会解二次方程式，在度量上采用了六十进制，现代时间和角度的单位皆源于此。
2．在尼罗河流域人们发现了几乎同一时期的莎草纸资料，其内容涉及如何疗伤治病，分发面包与啤酒，以及求出金字塔某一部分的体积。
科学理论的出现3．在埃及和美索不达米亚，科学知识主要是实用性的，绝少有理性的归纳。
在寻求自然现象的基本起因的第一批希腊学者中，哲学家台力斯便是其中一位。
他在公元前6世纪提出了一个观点：地球是一个圆盘，漂浮于宇宙的一种基本元素----水----之上。
数学家和哲学家毕达哥拉斯是台利斯的追随者。
他掀起了一场运动，使数学成为所有科学研究的基础学科。
毕达哥拉斯理论的学者猜想：球形的地球以火为中心沿圆形轨道运动。
在公元前4世纪的雅典，爱奥尼亚人的自然哲学和毕达哥拉斯的数学科学相结合，形成了柏拉图和亚里士多德的哲学理论。
在柏拉图的学院里，演绎推理和数学表达得到了重视；在亚里士多德的演讲厅中，则强调归纳推理和定性的表述。
这两种科学方法之间的相互作用促成了日后大多数的科学进步。
4．在亚力山大大帝死后的所谓希腊时代期间，数学家、天文学家、地理学家爱罗托斯对地球作了极其精确的测量。
同样，天文学家阿里斯塔克斯提出了日心学说的星体系统，尽管该理论在古代未卜得到认同。
数学家、发明家阿基米德为力学和水静力学奠定了基础；哲学家、科学家狄奥弗拉斯塔成为植物学的奠基人；天文学家希巴克斯开创了三角学；解剖学家、医生海罗菲留斯和爱罗西斯特拉特在解剖的基础上建立了解剖学和生理学。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
THERMAL DECOMPOSITION OF SODIUM NITRATE
1487
THE KINETICS OF THE THERMAL DECOMPOSITION OF SODIUM NITRATE1 AND OF THE REACTION BETWEEN SODIUM NITRITE AND OXYGEN
Introduction Previously, investigations of the thermal decomposition of sodium nitrate dealt with the identification of the gaseous and solid products over various temperature Although there is considerable interest in the high temperature reactions of this compound, especially in the field of munitions, there is apparently a lack of fundamental work concerning the kinetics and the mechanism of the decomposition a t normal pressures. I n this investigation the reactions of sodium nitrite'-"J in argon and oxygen also were studied in order to clarify the origin of the gaseous products as well as the kinetics and the mechanism of the decomposition. Experimental
The sodium nitrate and sodium nitrite were of C.P. grade and purchased from the Fisher Scientific Company. The apparatus for this work consisted of a stainless steel thimble (reaction vessel) within a Vycor tube which is connected to a dual system consisting of a gas buret and compensating tube separated by a controlling manometer. The dual system of gas burets makes possible the continual observance of the rate process during the collection of the gaseous decomposition products. For measuring changes in volume of the system, while automatically maintaining a constant pressure,11 two platinum wires were sealed in the intervening manometer and connected to an electronic relay,'a used to operate a sole(1) This paper was presented, in part, before the Division of Physical and Inorganic Chemistry at the National Meeting of the American Chemical Society in Cincinnati, Ohio, April 6, 1955. (2) Also at The Newark College of Rutgers University. (3) Kurt Lesahewski, Ber., 72B, 1763 (1939). (4) Kurt Leschewski, Be?. Ges. Freunden Tech. Hoch Schule, Berlin, 1, 168 (1942). (5) K.Butkov,ActaPhysicochem., U.R.S.S., 6, 137 (1936); C.A., 81, 5G391 (1937). (6) P. L. Robinson, H. C. Smith and H. V. A. Brescos, J . Chem. Soc., 836 (1926). (7) J. Ray, J. Chem. SOC.,81, 177 (1905). (8) Ostwald, Ann., 860, 32 (1914). (9) Butkov and Chassovenny, Acta Phyaico. C h i n . U.R.S.S., 6, 645 (1936). (10) (a) T . M. Oza, J. Indian Chem. SOC., 22, 173 (1945); (b) T. M. Oza and Welawalker, ibid., 22, 248 (1945). (11) E . 5. Freeman end S. Gordon, THIS JOURNAL, 69, 1009 (1955). (12) A thyratron operated rolay similar to the Emil Greiner Co. Model E-2.
noid valvela (see Fig. 1). When there is a small increase in pressure, mercury-wire contact is made on the compensating tube side of the manometer, opening the solenoid valve. The mercury level in the gas buret falls until the original pressure of the system is restored, a t which oint the mercury-wire contact is broken and the solenoi! valve closes. The change in the mercury level is a measure of the increase in volume a t the initial pressure of the system. For reactions involving decreases in volume, the solenoid valve opens when the mercury-wire contact is broken. The position of the mercury leveling bulb is adjusted so that when the solenoid valve is open the mercury level in the buret will rise. A layer of mineral oil, one cm. thick, is used to coat the upper surface of the mercury in the gas buret to minimize reaction with NOz. It was determined experimentally that losses of NOz are almost completely eliminated, in this manner, within the limits of the experimental times used in the decomposition studies. The gases were determined by mass spectrometric analyses and the solid residues by X-ray diffraction and chemical methods. The mass spectrometer was the G.E. Analytical Model and the instrument was calibrated with 0 2 , Ns, NO, N20 and NOz. The results were confirmed by comparisons with synthetic mixtures of the gases in question. The Vycor vessel, containing a stainless steel reaction tube, is heated in a resistance furnace which is regulated to &2' by means of an indicating pyrometric proportioning controller. The vessel is also provided with an invertible side arm, located out of the heatin zone, which contains the sample prior to the reaction. &en the furnace has attained the desired temperature and the apparatus is filled with the appropriate gas the side arm is inverted, allowing the sodium nitrate or nitrite crystals (approximately 0.5 g.) to drop into the stainless steel tube where the reaction ensues. All the reactions are carried out at approximately one atmosphere of pressure and in a stainless #tee1reaction vessel having an inside diameter, i.d., of 1.60 cm., unless otherwise stated. The Chevenard automatic photographic recording thermobalance was used to obtain the thermograms for sodium nitrate and sodium nitrite in air. The sample weight was approximately 0.5 g. and the reaction was carried out in a Coors crucible (glazed) No. 000. The temperature of the furnace was increased at a rate of 15' per minute, and is noted a t the timing marks a t 2-minute intervals. The balance was calibrated with standard 100 and 200 mg. weights and the furnace cover adjusted so that buoyancy effects were negligible.