What is a critical point in chemistry?
The critical point is a term used in thermodynamics to describe the condition of pressure and temperature at which there will be no differences between phases, especially gas and liquid. In addition to such a point, the substance is not completely liquid or completely gaseous; It shows the properties of the liquid phase and the gas phase and is referred to as a supercritical fluid. There is also such a thing as a critical point of liquid. Such a point indicates the conditions of temperature, pressure and composition, behind which the mixture is divided into two or more different liquid phases.
The critical point of the specific substance often looks at the phase diagram, a graph that shows the behavior of the substance at different temperature and pressure conditions. Such a graph shows, for example, a curve representing a balance between the liquid and the gas phase. On one side of the line, at a higher temperature and lower pressure, the substance is a vital phase. On the other side of the line, at lower temperature and higher pressure, the substance is in the liquid phase. At sufficiently high temperature and pressure, this line ends at one point at which the phase disappearsé distinguishing liquid gas-critical point.
Supercritical fluids that exist outside the critical point of the substance have many different properties that resemble the properties of liquids and gases. Like liquids, supercritical fluids can serve as solvents; They can dissolve other substances. Like the gases, however, they have no surface tension.
Supercritical fluids that exist behind a critical point are relatively rare in nature, but exist. For example, deep sea volcanoes exist deep in the ocean and release extremely hot substances into extremely high -pressure conditions on the ocean bottom. This Heavod around the volcano, pushes it for its critical point and turns it into a supercritical fluid. Some planets, especially gas giants, contain substances at very high temperatures and pressure conditions at their nuclei. High temperature and pressure conditions are far beyond the critical point for appropriateÉ substances, so they exist as supercritical fluids.
There are many different applications of supercritical fluids in science, industry and other fields. Due to their solubility, they are useful for chemists to dissolve certain substances. They can also be used in the production of biodiesel fuels. For example, supercritical methanol is subjected to a number of reactions that result in the amount of usable fuel.