Boiling - would seem, the simple physical process known to everyone, at least once in life boiled the kettle. However it has many features which physicists study in laboratories, and hostesses — in kitchens. Even temperature of boiling is not constant, and changes depending on various factors.
Liquid boiling
When boiling, liquid begins to evaporate intensively, in it the steam bubbles rising to the surface are formed. When heating at first steam appears only on the surface of liquid, then this process begins on all volume. There are small bubbles at a bottom and walls of ware. At temperature increase pressure in bubbles increases, they increase and rise up.
When temperature reaches a so-called boiling point, rough formation of bubbles begins, they become much, liquid begins to boil. Steam which temperature remains to a constant is formed, all water will not boil away yet. If steam formation happens in usual conditions, at the standard pressure of 100 MPas, its temperature is equal 100 wasps. If artificially to increase pressure, it is possible to receive superheated steam. Scientists managed to heat water vapor to temperature of 1227 wasps, at further heating the dissociation of ions turns steam into plasma.
At the set structure and constant pressure temperature of boiling of any liquid is constant. In textbooks and handbooks on physics it is possible to see the tables specifying temperature of boiling of various liquids and even metals. For example, water begins to boil at a temperature of 100 wasps, ethyl alcohol at 78.3 OS, air at 34.6 OS, gold at 2600 OS, and silver at 1950 OS. These are data for standard pressure of 100 MPas, it pays off at sea level.
How to change boiling temperature
If pressure decreases, temperature of boiling decreases even if the structure remains the same. It means that if to rise with a water kettle by the mountain 4000 meters high and to put it on a fire, water will begin to boil at 85 OS, for this purpose it is required much less firewood, than below. Comparison with the pressure cooker in which pressure artificially increases will be interesting to hostesses. Water boiling temperature at the same time also increases at the expense of what food is cooked much quicker. Modern pressure cookers allow to change smoothly temperature of boiling from 115 to 130 wasps and more. One more secret of temperature of boiling of water consists in its structure. Hard water which part various salts are begins to boil longer and demands more energy for heating. If to add two tablespoons of salt to water liter, temperature of its boiling will increase by 10 wasps. The same can be told about sugar, 10% sugar syrup begin to boil at a temperature of 100.1 wasps.