You physical states of matter they correspond to the ways in which matter can appear in nature.
These states are defined according to pressure, temperature and above all, by the forces acting on the molecules.
Matter, made up of small particles (atoms and molecules), corresponds to everything that has mass and occupies a certain place in space.
Being able to present itself in three states: solid, liquid and gaseous.
Solid, Liquid and Gaseous States
In the solid state, the molecules that make up matter remain tightly joined and have their own shape and constant volume, for example, the trunk of a tree or ice (water in a solid state).
In the liquid state, the molecules already present a smaller union and greater agitation, so that they have a variable shape and constant volume, for example, the water in a certain container.
In the gaseous state, the particles that form matter exhibit intense movement, as the cohesion forces are not very intense in this state. In this state, the substance has variable shape and volume.
Thus, in the gaseous state, matter will have a shape according to the container it is in, otherwise it will remain shapeless, just like the air we breathe and do not see.
As an example, we can think of the gas cylinder, which has compressed gas that has acquired a certain shape.
Physical State Changes
At physical state changes they basically depend on the amount of energy received or lost by the substance. There are essentially five Law Suit of changes in physical state:
- Fusion: passage of solid state to liquid state through heating. For example, an ice cube that comes out of the freezer melts and turns into water.
- Vaporization: passage of liquid state to gaseous state which is obtained in three ways: heating (heater), boiling (boiling water) and evaporation (clothes drying on the clothesline).
- Liquefaction or Condensation: passage of gaseous state to liquid state through cooling, for example, the formation of dew.
- Solidification: passage of liquid state to solid state, that is, it is the inverse process to fusion, which occurs through cooling, for example, liquid water transformed into ice.
- Sublimation: passage of solid state to gaseous state and vice versa (without passing through the liquid state) and can occur by heating or cooling matter, for example, dry ice (solidified carbon dioxide).
Other Physical States
In addition to the three basic states of matter, there are two more: plasma and Bose-Einstein condensate.
Plasma is considered the fourth physical state of matter and represents the state where the gas is ionized. The sun and stars are basically made of plasma.
It is believed that most of the matter that exists in the universe is in a plasma state.
In addition to plasma, there is also a fifth state of matter called the Bose-Einstein condensate. Which received this name because it was theoretically predicted by physicists Satyendra Bose and Albert Einstein.
A condensate is characterized by particles that behave in an extremely organized way and vibrate with the same energy as if they were a single atom.
This state is not found in nature and was first produced in 1995 in a laboratory.
To reach it, it is necessary that the particles be subjected to a temperature close to absolute zero (-273 ºC).
Solved Exercises
1) Enem - 2016
First, in relation to what we call water, when it freezes, we seem to be looking at something that has become stone or earth, but when it melts and melts.
dispersed, it becomes breath and air; the air, when it is burned, becomes fire; and, conversely, fire, when it contracts and extinguishes itself, returns to the form of air; the air, again concentrated and contracted, becomes cloud and fog, but from these states, if it is further compressed, it becomes running water, and from water it becomes earth and stones again; and in this way, as it seems to us, they give birth to each other in a cyclical way.
PLATO. Timaeus-Critias. Coimbra: CECH, 2011.
From the point of view of modern science, the “four elements” described by Plato actually correspond to the solid, liquid, gas and plasma phases of matter. The transitions between them are now understood as macroscopic consequences of transformations undergone by matter on a microscopic scale.
Except for the plasma phase, these transformations undergone by matter, at a microscopic level, are associated with a
a) exchange of atoms between the different molecules of the material.
b) nuclear transmutation of the material's chemical elements.
c) redistribution of protons between the different atoms of the material.
d) change in the spatial structure formed by the different constituents of the material.
e) alteration in the proportions of the different isotopes of each element present in the material.
Alternative d: change in the spatial structure formed by the different constituents of the material.
2) Enem - 2015
Atmospheric air can be used to store the excess energy generated in the electrical system, reducing its waste, by through the following process: water and carbon dioxide are initially removed from the atmospheric air and the remaining air mass is cooled to - 198°C. Present in the proportion of 78% of this air mass, gaseous nitrogen is liquefied, occupying a volume 700 times smaller. The excess energy from the electrical system is used in this process, being partially recovered when liquid nitrogen, exposed to room temperature, boils and expands, turning turbines that convert mechanical energy into energy electric.
MACHADO, R. Available at: www.correiobraziliense.com.br. Accessed on: 9 Sept. 2013 (adapted).
In the process described, the excess electricity is stored by the
a) expansion of nitrogen during boiling.
b) heat absorption by nitrogen during boiling.
c) carrying out work on nitrogen during liquefaction.
d) removal of water and carbon dioxide from the atmosphere before cooling.
e) heat release from the nitrogen to the surroundings during liquefaction.
Alternative c: carrying out work on nitrogen during liquefaction.
3) Enem - 2014
The rise in the temperature of the waters of rivers, lakes and seas reduces the solubility of oxygen, putting at risk the various forms of aquatic life that depend on this gas. If this temperature rise happens by artificial means, we say that there is thermal pollution. Nuclear power plants, by the very nature of the energy generation process, can cause this type of pollution. What part of the power generation cycle of nuclear power plants is associated with this type of pollution?
a) Fission of radioactive material.
b) Condensation of water vapor at the end of the process.
c) Conversion of energy from turbines by generators.
d) Heating of liquid water to generate water vapor.
e) Release of water vapor on the turbine blades.
Alternative b: Condensation of water vapor at the end of the process.
See too:
- Physics Formulas
- Physical and chemical transformations
- Physical and chemical phenomena
