Again the equation is too complicated to consider at this point. More precise definitionsof oxidizing and reducing agents are. Remembering these definitions is essential, and easily done using this convenient acronym:. The equation below shows an obvious example of oxygen transfer in a simple redox reaction:. Copper II oxide and magnesium oxide are both ionic compounds. If the above is written as an ionic equation, it becomes apparent that the oxide ions are spectator ions. Omitting them gives:.
In the above reaction, magnesium reduces the copper II ion by transferring electrons to the ion and neutralizing its charge. Therefore, magnesium is a reducing agent. Another way of putting this is that the copper II ion is removing electrons from the magnesium to create a magnesium ion.
The copper II ion is acting as an oxidizing agent. Indol is absorbed and oxidize d into indoxyl, which combines with potassium and sulphuric acid and is thus excreted. Other forms of contact rapidly oxidize d and went out of business. The cables are wrapped in cotton duck soaked in oxidize d oil and varnish, and are sheathed in sheet iron. Potassium cyanide is a powerful reducing agent see p. It is not impossible, even, that we also must consider negative ions FeO22 and their tendency to be oxidize d.
The iron is said to have oxidized into rust. The chemical reaction is:. The iron metal is oxidized to form the iron oxide known as rust. Electrochemical reactions are great examples of oxidation reactions. When a copper wire is placed into a solution that contains silver ions, electrons are transferred from the copper metal to the silver ions. The copper metal is oxidized. Silver metal whiskers grow onto the copper wire, while copper ions are released into the solution.
Another example of oxidation where an element combines with oxygen is the reaction between magnesium metal and oxygen to form magnesium oxide. Many metals oxidize, so it's useful to recognize the form of the equation:. Once the electron was discovered and chemical reactions could be explained, scientists realized oxidation and reduction occur together, with one species losing electrons oxidized and another gaining electrons reduced.
A type of chemical reaction in which oxidation and reduction occurs is called a redox reaction, which stands for reduction-oxidation. The oxidation of a metal by oxygen gas could then be explained as the metal atom losing electrons to form the cation being oxidized with the oxygen molecule gaining electrons to form oxygen anions.
In the case of magnesium, for example, the reaction could be rewritten as:. Oxidation in which oxygen is involved is still oxidation according to the modern definition of the term. However, there is another old definition involving hydrogen which may be encountered in organic chemistry texts. This definition is the opposite of the oxygen definition, so it may cause confusion.
Still, it's good to be aware. According to this definition, oxidation is the loss of hydrogen, while reduction is the gain of hydrogen.
Variant: oxidization. Compare: reduction. Oxidation is defined as a process in which an electron is removed from a molecule during a chemical reaction.
What happens in oxidation? During oxidation, there is a transfer of electrons. In other words, during oxidation, there is a loss of electrons. There is an opposite process of oxidation known as a reduction in which there is a gain of electrons. In the above reaction, the Mg ion loses electrons to form magnesium oxide.
Similarly, CuO gains an electron to become pure Cu copper. Oxidation takes place as a molecule, atom, or ion raises its oxidation state. The reverse mechanism is known as reduction , which happens as the electron gain or the oxidation state of the atom, molecule, or ion reduces. Another good example is that hydrofluoric acid is formed by the reaction of hydrogen and fluorine gas:.
The above reaction oxidizes hydrogen and reduces fluorine. If two half-reactions are described, the reaction can be best understood.
Oxygen has been added to a compound as an older method of oxidation. That was because the first understood oxidizing agent was oxygen gas O 2. Although oxygen is typically added to a compound in compliance with the loss of electron requirement and an oxidation state increase, the oxidation concept has been expanded to incorporate additional chemical reactions. The old oxidation concept of iron in combination with oxygen to produce iron oxide is a classic example of an oxidation reaction.
The iron oxidized in rust. The chemical reaction is the following:. Oxidation involving oxygen is the modern meaning of the term oxidation. Also, there is another description of hydrogen that can be used in organic chemistry. This is the reverse of the concept of oxygen, and can thus create confusion.
Oxidation is the loss of hydrogen, according to the description, whereas the reduction, in hydrogen gain. Ethanol is known to be oxidized by the loss of hydrogen. By reversing the equation and adding hydrogen to ethanol, ethanol can be reduced.
The oil rig can be used to understand the modern concept of oxidation and reduction. It deals with electrons only and not oxygen or hydrogen. It is a simple technique to recognize and remember which element is oxidized and which one is reduced. This is a convenient abbreviation to represent the term electron loss or gain. An atom becomes an ion if it gains or loses an electron. The term used to explain this mechanism rests on whether an atom has lost oxidation or gained reduction an electron.
So, it can be said that the hydrogen atom has oxidized and an oxidation reaction took place. Conversely, if a chlorine Cl atom gains an electron, it becomes a negatively charged ion Cl —. Therefore, the chlorine atom is said to be reduced and the reduction reaction occurred. Oxidation and reduction processes take place at the same time and cannot be carried out independently. The individual reactions of oxidation and reduction are taken as half-reactions, subsequently, two half-reactions combine to form a full reaction.
The electrons gained or lost are explicitly used such that the half-reaction with the electric charge is balanced.
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