air around us plays an important role in biological organisms inhabiting the Earth.But human activity is associated with a variety of technological processes, identified the substance in the category of technically important gases.He was subjected to a thorough study on the subject of physical properties.During the experiments revealed the physical properties of the air, some of their features and dependencies.
difficulty of working with air is that it is a heterogeneous substance, and is a solution of a large number of components.But all the same kind of stability of its members present.
natural recipe vital gas (air) includes virtually stable set of ingredients.To date, they have the following percentage of nitrogen takes 78 percent oxygen - 20, carbon dioxide - 0.03 percent.Steam, other gases and even solids occupy about one and a half percent.Specific heat capacity of air depends not only on other physical factors, but varies depending on the internal content (composition) gas.
the collection and analysis of data on the thermodynamic properties of air was spent labor collectives of the world's largest laboratories.These studies originate from the end of the XIX century and actively conducted today.Their results are used in the calculation of a wide variety of energy and air separation plants, machines for the chemical industry and other devices.
Specific heat is the amount of air, which determines the amount of heat energy that must be spent to one kilogram of this gas changed its temperature by one degree (Kelvin).Taking into account the previously mentioned dependence of this quantity on many factors for engineering purposes are different charts and tables.They indicate how the specific heat of air depending on the temperature or humidity.
For a more in-depth study of this matter have been conducted experiments, which use dry air, cleaned of carbon dioxide.In the first case it was determined by the specific heat at constant pressure (Cp), the second at constant volume (Cv) and the same thermometer.Interestingly, at 0 ° Cp value was 0.2402 cal / g · °, and Cv of the same gas - 0.1713 cal / g-deg.The ratio of these values gives the following thermodynamic measure of importance in thermodynamics.
To determine the gas constant (R) calculate the difference of specific heats gas being studied at constant pressure (Cp) and at constant volume (Cv).The physical meaning of this value is to determine the expansion work, for example, one kilogram of gas (air) when the temperature thereof is increased by one degree (Kelvin).
In previous experiments studied the physical properties of dry air.In actual practice, have to take into account the percentage of steam in it (moisture).The specific heat of air containing a certain amount of water (steam), has its own dependence and patterns of change.
Moist air has become the subject of a direction in physical research, because the vapor content in it affects a number of physical and even chemical processes.Living organisms is no exception.Changes in humidity not only affects the microclimate conditions of the premises (offices, workshops, laboratories), but also has an impact on the performance of employees, the safety of a number of substances, and even the functioning of some devices.
not only a statement of facts, but also the search for different ways to influence the properties of the air is the subject of research.They are of major importance in various fields of human activity, ranging from the chemical industry, to construction of dwellings.
