Pressure of saturated steam is one their characteristics of various liquids and is given as a reference material in special literature. Knowledge of this size allows to induce to begin to boil by change of external pressure liquid or, on the contrary, to form condensate of a gaseous product.
As saturated steam represents one of components thermodynamic of an equilibrium system homogeneous on structure, but substance, various on phase fractions, at a size of pressure created by it this knowledge in practical activities allows to use understanding of influence of separate physical factors, for example, when determining speed of burning out of any given liquids in case of ignition and so forth.
Dependence of pressure of saturated steam on temperature
Pressure of saturated steam becomes that more, than temperature increases more. At the same time change of sizes is not directly proportional, and happens much quicker. It is connected with the fact that with increase in temperature the motion of the molecules relatively each other accelerates and it is easier for them to overcome forces of a mutual attraction and to pass into other phase, i.e. the quantity of molecules in liquid state decreases, and increases in gaseous until all liquid does not evaporate. This increasing pressure also causes lifting of a cover in a pan or a teapot when water begins to begin to boil.
Dependence of pressure of saturated steam on other factors
Has on the size of pressure of saturated steam impact and quantity of the molecules which turned into gaseous state as their number determines the mass of the formed steam in the closed vessel. This size is not a constant as at the difference of temperatures of a bottom of a vessel and the cover closing it constantly there are two mutually opposite processes – steam formation and condensation. As for each substance at a certain temperature there are known indicators of transition of a certain quantity of molecules from one phase of a condition of substance in another, it is possible to change the size of pressure of saturated steam by change of volume of a vessel. So, the same volume of water, for example 0.5 l, will create pressure, different in size, in a 5 liter canister and a liter teapot. The defining factor for determination of help size of pressure of saturated steam at the invariable volume and gradual temperature increase is the molecular structure of the liquid subjected to heating. So, indicators for acetone, alcohol and usual water significantly will differ from each other. To see process of boiling of liquid it is necessary not only to bring pressure of saturated steam to certain limits, but also to correlate this size to the external atmospheric pressure as process of boiling is possible only when pressure is outside higher than pressure in a vessel.