For centuries, physicists assumed that the temperature is determined by the presence of gases invisible and weightless substance caloric.It has been many theories to explain its movement within the material and across subjects.Only MVLomonosov was able to explain the real nature of matter, creating molecular-kinetic theory of gases.In their arguments and calculations he was able to show that caloric in nature.The temperature depends on the speed of the random motion of the molecules.He introduced the concept of internal energy, and explained how it changes in the actual process.
What arguments led MVLomonosov to prove the molecular-kinetic theory of gases
first expressed the assumption that no caloric does not exist in nature, he met strong resistance from the venerable scientists of the period.They all recognized the existence of caloric and novice researcher - not.Then, at a meeting with German and British physicists I was told the following: "Dear teachers.Where did the body's caloric cow?She ate cold grass, and then her body was warmed by what happened in its internal change in internal energy.Where did it come about?A heat to the origin of the body due to the fact that the grass has a chemical energy which the animal is transformed into heat.So, we observe the phenomenon of energy transfer from one state to another. "He listened, asked dozens of questions.Following the discussion it had been formulated and the law of change of energy (also known as the law of conservation of energy), which was recognized by all present.Later, it was published a small collection of hypotheses, which was the first edition of which was recognized by the molecular-kinetic theory of gases.
What did the researchers theory MVUniversity
It now seems that everything is logical in thermodynamics.But we should remember that it has been more than 250 years from the first assumption to this day.French explorer Jacques Charles discovered the law of proportionality pressure increase with increasing temperature of the gas.He then explained the change in internal energy of the gas when heated.He brought his formula.His research in 20 years continued Gay-Lussac, who investigated the heating of the gas at constant pressure.He watched as the piston changes its position, placed inside a glass cylinder is heated and cooled.Here he came close to opening the concept of the gas constant.He did not use research, which performed 140 years earlier Robert Boyle.Only work Mariotte made later formulated in the law Boyle helped Benoit Paul Emile Clapeyron first formulated the concept of the ideal gas law.
After 40 years of DIMendeleev added equation of state of the results of their research.Now the law of Clapeyron-Mendeleev is the basis for the thermodynamics of the whole world.He mathematically determines the change in internal energy of the gas temperature.Discoveries confirmed the basic laws and practices.It was created thermal machines working on thermodynamic cycles of Otto, Diesel, Trinklera and other scientists.
only at the beginning of the XX century has been generalized the experience of predecessors, and wrote a textbook on molecular physics and engineering thermodynamics, which are neatly and logically set out the entire set of discoveries.
few words about the state of the ideal gas law
pV = mRT
Today, the derivation of all the dependencies using the equation of state of an ideal gas.Nobody confuses its constituent parameters that have well-defined concept.Conclusions from the main gas law gives another important formula, which characterizes the change in internal energy:
dU = cvDT,
here dU is the differential change in internal energy, and cv - is the specific heat of the gas at constant volume.As a result of discussions about the nature of the gas constant R it found that she characterizes the work of the gas at constant pressure.
