Any change in the state of matter is associated with metamorphoses of temperature, pressure. One substance can be represented in the following states of aggregation: solid, liquid, gaseous.
Note that as the transition progresses, no change in the composition of the substance is observed. The transition of a substance from a liquid to a solid state is accompanied only by a change in the forces of intermolecular interaction, the arrangement of molecules. The transformation from one state to another is called a phase transition.
Melting
This process involves the transformation of a solid into a liquid. For its implementation, an increased temperature is needed.
For example, one can observe such a state of matter in nature. Physics easily explains the process of melting snowflakes under the action of spring rays. Small ice crystals that are part of the snow, after warming the air to zero, begin to collapse. Melting occurs gradually. First, the ice absorbs heat energy. As the temperature changes, the complete transformation of ice into liquid water occurs.
It is accompanied by a significant increase in the speed of particles, thermal energy, an increaseinternal energy.
After reaching the index, called the melting point, there is a break in the structure of the solid. Molecules have more freedom, they "jump", occupying different positions. A molten substance has more energy than a solid state.
Cure temperature
The transition of a substance from a liquid state to a solid state is carried out at a certain temperature value. If heat is removed from the body, then it freezes (crystallizes).
Cure temperature is considered one of the most important characteristics.
Crystallization
The transition of a substance from a liquid state to a solid state is called crystallization. When the transfer of heat to the liquid stops, the temperature drops to a certain value. The phase transition of a substance from a liquid to a solid state in physics is called crystallization. When considering a substance that does not contain impurities, the melting point corresponds to the crystallization index.
Both processes proceed gradually. The crystallization process is accompanied by a decrease in the average kinetic energy of the molecules contained in the liquid. The forces of attraction, due to which the particles are held in a strict order, inherent in solids, increase. After the particles acquire an ordered arrangement, a crystal will form.
The state of aggregation is the physical form of a substance, presented in a certainrange of pressures and temperatures. It is characterized by quantitative properties that are changed in selected intervals:
- the ability of a substance to change shape and volume;
- absence (presence) of long-range or short-range order.
The crystallization process is associated with entropy, free energy, density, and other physical quantities.
In addition to liquids, solids, gaseous forms, another state of aggregation is released - plasma. Gases can pass into it in the event of an increase in temperature at a constant pressure.
The limits between the various states of matter are not always strict. Physics has confirmed the existence of amorphous bodies capable of maintaining the structure of a liquid with little fluidity. Liquid crystals have the ability to polarize the electromagnetic radiation that passes through them.
Conclusion
In order to describe various states in physics, the definition of a thermodynamic phase is used. Critical phenomena are states that describe the transformation of one phase into another. Solid bodies are distinguished by the preservation of their average position over a long time period. They will make slight oscillations (with a minimum amplitude) around the equilibrium position. Crystals have a certain shape, which will change when it goes into a liquid state. Information about boiling (melting) temperatures allows physicists to use transitions from one state of aggregation to another topractical purposes.
