🔎 Chemical Reaction – Definition and Explanations



A chemical reaction it is a transformation of matter during which the chemical species (atomic, ionic or molecular) that make up the matter are modified: the species that are consumed are called reactants. The species formed during the reaction are called (reaction) products. Since the work of Lavoisier (1777), scientists know this chemical reaction (A chemical reaction is a transformation of matter during which …) occurs without measurable changes in mass: “Nothing is lost, nothing is created, everything (The whole understood as the whole of what exists is often interpreted as the world or …) transforms ”which translates the mass conservation (Before discovering that mass is one of the forms of energy, the laws of physics and ….

Chemical reactions cause a change in the chemical nature of the it matters (Matter is the substance that makes up any body having a tangible reality. Its …)purely physical transformations, such as changes of state (merger, solidification (Solidification is the operation during which a liquid passes into a state …), evaporation (Evaporation is a gradual transition from a liquid to a gaseous state. It’s different …), boiling (Boil is the formation of bubbles during a violent change of a body …)…), wear and erosion, breakage … A reaction can break freepower (In common sense, energy means anything that allows you to do work, produce energy, etc.) (usually in the form of heat (In common parlance the words heat and temperature often have an equivalent meaning: …), but also light), is then called “exothermic”. It may require a supply of energy, in the form of heat (hence “producing cold”) or light (Light is the set of electromagnetic waves visible to the eye …), is then called “endothermic”. In general, a reaction can only take place if certain conditions are met (presence of all reactants, temperature (Temperature is a physical quantity measured using a thermometer and …)from pressure (Pressure is a fundamental physical notion. You can think of it as a reported force …), from the light). Some reactions require or are facilitated by the presence of a chemical called catalyst (In chemistry, a catalyst is a substance that increases the rate of a chemical reaction; …). Classically, chemical reactions involve changes that affect the movement of electrons, the formation and breaking of chemical bonds. However, the general concept of chemical reaction, especially the notion ofequation (In mathematics, an equation is an equality that relates different quantities, usually …) chemistry, it is also applicable to elementary transformations of particles and nuclear reactions. In Organic chemistry (Organic chemistry is a branch of chemistry that deals with the scientific study of …), various chemical reactions are combined in chemical synthesis to obtain the desired product. In biochemistry (Biochemistry is the scientific discipline that studies the chemical reactions that occur …)series of chemical reactions catalyzed by enzymes form metabolic pathways, through which usually impossible syntheses and decompositions are carried out in a cell.

Microscopic vision (at the atomic level)

Chemical reaction: exchange ofatoms (An atom (from the Greek ατομος, atomos, “which cannot be …) between compounds, example of combustion (Combustion is an exothermic redox chemical reaction. When the …) from methane (Methane is a hydrocarbon with chemical formula CH4. It is the simplest compound in the …) in the dioxygen (Dioxygen is a molecule composed of two oxygen atoms, called O2, …).

Matter is composed of atoms grouped into chemical compounds, during a chemical reaction, the compounds exchange their atoms; in doing so, the nature of the compounds changes. Chemical reactions only concern the modifications of the bonds between atoms (covalent bonds, ionic bonds, metal bonds).

To represent the phenomena that occur during a chemical reaction, we write a chemical equation.

reaction rate

The study of the energy of the system (thermochemistry) allows to know if a reaction can occur or not, what initial energy is necessary to supply to cross the barrier. But there is another one setting (A parameter is in a broad sense an element of information to be taken into account …) important: the speed of reaction.

The rate of reaction is the measure of the variation with the time (Time is a concept developed by humans to learn the …) concentrations or / and pressures of the substances involved in this reaction. Reaction rate analysis is important for many applications such asengineering (Engineering refers to all functions ranging from design and studies to …) chemistry or the study of chemical equilibria.

The reaction rate depends on:

  • The concentration of the reagents: a higher concentration increases the possibility of collision (A collision is a direct impact between two objects. Such an impact conveys a part of …) between molecules and thus increases the reaction rate.
  • The surface (A surface generally refers to the surface layer of an object. The term a …) available for the contact between molecules especially of the solid in heterogeneous systems. A larger surface produces a faster reaction rate.
  • The pressure, which increases, decreases the volume (Volume, in the physical or mathematical sciences, is a quantity that measures the extent …) and therefore the distance between the molecules. This increases the frequency (In physics, frequency generally refers to the measurement of the number of times a …) collisions of molecules.
  • The energy ofto enable (Activation may refer to 🙂 which is defined as the Quantity (Quantity is a generic term of metrology (account, amount); a scalar, …) of energy necessary for the reaction to start and be maintained spontaneously.
  • The increase in temperature activates the reaction by increasing the energy of the molecules and creating more collisions per unit of time
  • The absence or presence of a catalyst alters the mechanism of the reaction which, in turn, increases the speed of the reaction by lowering the required activation energy. A catalyst is not destroyed during the reaction.
  • For some reactions, the presence of electromagnetic radiation, especially ultraviolet radiation, is required to break the bonds to initiate the reaction.

Note that some reactions do not depend on the concentration of the reactants.


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