well-known fact that the substance may be one of the states - gas, liquid, solid.And it can pass from one to another.The simplest example - a piece of ice melts into a liquid and then steam.Throughout this process, the conversion in the solid phase pairs very interesting point and one of its parameters - the specific heat of melting.
at our experience says that any substance can be melted.This is also evidenced by the entire history of civilization.The opening point of the substance has been one of the greatest inventions in human development.But the melting - a difficult process.When you hold it there a lot of questions, and one of them about how much you need coal (peat, wood, gas) to melt a piece of iron or copper.And here again we must refer to the concept of "heat of fusion".
If we recall how the melting, it is possible to distinguish several stages.Take for example lead.The first step is the heating of lead, the temperature rises to 327 degrees Celsius (the melting point).After melting has begun, for a long time, nothing happens.
lead temperature, despite the heat supplied to it, is kept constant and this until the end of the whole process.And only after that with continued heating temperature begins to rise again.From the observed pattern followed by some conclusions.In solid all molecules are in a certain order and are rigidly connected with neighboring molecules.
order to enable them to move freely in the other place, connections with neighboring molecules it is necessary to break, which is what happens in the process of melting.To do this, the body may have to pass a certain rate of heat, called the heat of fusion.For each substance, require different amounts of heat.The reason is due to the property of a substance such as the specific heat of melting, which is defined as the amount of heat it takes to melt one kilogram of matter.The unit is Joule / kilogram.
As already mentioned, each has its own material, this quantity.The specific heat of melting lead different from the same quantity of ice.This raises a very interesting point.Specific heat of steel melting averages 85 kJ / kg, and the water (ice), the same parameter is an average of 335 kJ / kg.In ice high value of this parameter can be considered as a great gift from nature.
Indeed, thanks to the all the snow, the ice melts instantly, and everything happens for a long time.Otherwise, the snow has melted would be very fast, and there have been floods abounding and more devastating.In addition, these unique properties of water contribute to the stabilization of the global climate.
There are tables with data on the specific heat of fusion of the individual materials.Knowing this value is calculated as the heat necessary to melt the material and determine how much fuel for melting.If the body is heated to the melting point, the heat is only needed for melting, and if the temperature is below the melting point, the heat required for heating the material to melting temperature.
These calculations are extremely useful in industry to calculate the cost of production.
By the way, during the cooling of the molten material, the reverse process of melting - crystallization.In this case, the cooling of the substance recovered broken bonds between molecules and generates heat.
Considering the process of melting the substance and going at the same phenomenon has been defined such a thing as the heat of fusion.A comparison of this indicator for different substances, it is determined how the high value of this parameter at the ice has beneficial effects on the climate.
