Physicochemical phenomena are those that modify, at the same time, the internal ( molecular ) nature of the substances, at the same time as their physical state, that is to say, their form or the disposition of their constituent elements.
Traditionally distinguishes between physical and chemical phenomena on the basis that the former modify the state of an object or a substance without altering its composition, while the latter alter the very essence of the object or substance.
Thus, melting an ice cube or boiling water will be examples of physical phenomena, because the substance retains its composition (H 2 O), while the oxidation of an iron nail or the combustion of wood will be physical phenomena that transform a substance in a different one. The physicochemical phenomena , however, perform both tasks together, so its subject are relations and molecular interactions that presents the matter in its various states and physical processes.
The origin of this discipline dates back to the 19th century, when the American chemist Willard Gibbs published his Study on the balance of heterogeneous substances , where he postulated terms such as free energy, chemical potential and phase rule, which today constitute some of the main points of interest of physicochemistry.
We could conclude that the area of ??expertise of physical chemistry are those perspectives that physics and chemistry separately fail to address or explain satisfactorily.
Examples of physicochemical phenomena
- Catalysis. This is the name given to the processes by means of which the speed of a chemical reaction determined through the participation of another substance, alien to the original reaction, which is called a catalyst and which, by not participating in the reaction, maintains its mass, is increased. constant.
- Transportation . Transport phenomena are those that transmit a quantity of movement, energy and / or matter between substances or actors involved, and that are studied from three different levels: microscopic, macroscopic and molecular, using a joint physical-chemical perspective -mathematics.
- Ionic exchanges. It is thus known the process of transmission of electrically charged atoms or molecules (ions) between two electrically conductive substances (electrolytes) or one of them and a chemical complex ( coordination bonds ). It is also a phenomenon propitiated in processes of purification, separation or decontamination of ionic solutions.
- Chemical balance. This equilibrium appears when the substances involved in a reversible chemical reaction do not have a favorable concentration in either direction in which the chemical change can occur (forward or reversed).
- Solutions The solutions are homogeneous mixtures between two or more pure substances that react with each other and are together in variable proportions. Between them an electrochemical type of link is produced that recomposes the atomic bonds of each one, so they can not be separated except by means of certain physicochemical processes.
- Liquid crystal. Liquid crystal is called a very particular state of aggregation of matter, which responds to both the physical considerations of the solid state and the liquid simultaneously. They are of particular interest for the physicochemical study of the phases.
- Relaxation of polymers. It is called a phenomenon in which certain plastics (and hence their name) modify their shape and structure in the face of a sustained effort applied to them, ordering the polymer chains in the most energetically favorable position, that is, the that contains less entropy.
- Quantum leaps A quantum leap is the sudden and sudden change of state of matter, which occurs at atomic levels and is part of the phenomena explored by means of spectroscopy (quantum chemistry). One is, for example, of the sudden state of excitation of an electron in an atom when being hit with a photon (light).
- Electrolysis. Mechanism used to separate the chemical elements within a compound from the introduction of electricity, forcing the capture and release of electrons in each pole (cathode and anode respectively), thus generating processes of reduction and oxidation at the same time.
- Energy transfers . Physical chemistry is particularly interested in the phenomena of energy transfer, either caloric or electrical, and therefore attends to almost all cases of energy interaction of the molecules of two or more substances interacting.