Morning dew on leaves and fogging the windshield of your car, the disappearance of gasoline from storage tanks and the long awaited rain falling, all of these processes combines constant change of the substance of its state of aggregation.A more detailed study of the conditions of the transition vapor - liquid and even couples - solid body, it was observed that the impact on their course has not only the temperature but also the pressure.
So under thermodynamics, among other physical concepts appeared determining the vapor, and the vapor pressure of each substance has been the subject of study and exact measurements.All the descriptions and definitions of the vapor is reduced to consideration of a closed system in which the agent resides simultaneously in two states of aggregation, vapor and liquid (sometimes rigid body), and the balance between them is achieved by the presence of a certain temperature and pressure.Their variation leads to boiling or condensation liquids or sublimation, desublimation solids.
In other words, the concentration of the substance in the vapor state reaches the maximum possible value for the existing temperature and pressure.The system takes a certain position of equilibrium in which the amount of steam and its properties get constant values.
processes occurring within a closed system, are interesting in that the vapor pressure does not depend on the volume of the vessel.If provoke an increase (decrease) in volume, for example, by means of the piston, in the first case, this leads to an increase in the quantity of steam and in the second - to a condensation transition vapor into the liquid.Affect the vapor pressure can be a change in temperature.
able to describe the vapor pressure formula, which can be found in the pages even school textbooks.But a clear manifestation of the properties of saturated steam can be seen in the game "chick drinks" which rightfully won the title psevdovechnogo engine.Uncomplicated design of two soldered together flasks designated middle axle-type swing for children, demonstrates how a periodic evaporation and poured into the air conditioning results in the toy in constant movement.Vapour pressure receives periodic pulses to change by lowering (cooling) head toy in a container with water.
But the main practical application of knowledge of the properties of the vapor goes far beyond the creation of idle fun and toys.Widespread instruments for measuring humidity and dew point.Knowledge of methods of regulation of humidity allows us to achieve the most favorable micro-climatic conditions in the premises.It not only plays an important role in creating favorable conditions for human life, but also necessary for the preservation of objects in warehouses, archives, libraries ...
special role these issues play in the energy industry, which have to deal with the storage and transportationlarge volumes of flammable liquids and gases.The use of special valves that are vented vapor pressure of gasoline, although it leads to a partial loss of valuable substances, but protects against more unpleasant consequences arising from excess pressure fuel in large tanks for storage.Gas liquefaction technology is largely based on the laws and properties of the vapor, its application not only facilitated the transportation of this type of fuel, but also to make it available for use in the automotive industry.Vehicles with HBO is not only financial savings of their owners, but also a beneficial effect on the environment.
