What Is a Reducing Agent?

A reducing agent is a substance that loses or deviates from an electron in a redox reaction. The reducing agent itself is reducing and is oxidized, and its product is called an oxidation product. The reduction and oxidation reactions occur simultaneously, that is, the reducing agent undergoes an oxidation reaction with the reduced substance, and is itself oxidized to become an oxide. The reactant whose elevated valence of a certain substance is contained is a reducing agent.

Antioxidant in a broad sense refers to a general term for substances such as scavengers, blockers, and repair agents for free radicals and active oxygen ^[1]

(1) active metal simple substances (such as sodium, magnesium,

Change in valence

The reaction between a substance and oxygen to form an oxide is called an oxidation reaction. The reaction with oxygen-containing compounds is not necessarily an oxidation reaction. For example, if the generated compound contains oxygen but is not an oxide, it is not called an oxidation reaction, and an oxidation reaction refers to a reaction with an increased valence. The concepts of oxidation and reduction have long been recognized and applied by people. There is a process for people to understand it, and it is gradually deepened. The oxidation reaction originally meant the combustion of fuel in air or oxygen, the burning and rusting of metals, the breathing of living things, and so on. Reduction reactions are described as the extraction of metals from metal ores, and so on. So getting oxygen is an oxidation reaction, and losing oxygen is a reduction reaction. However, it was found that in some reactions, oxidation did not produce oxygen, but lost hydrogen. For example, the hydrogen sulfide solution is exposed to the air and reacts with oxygen to generate sulfur and water. 2H2S + O2 = 2H2O + 2S In this reaction, H2S is oxidized to lose hydrogen, and oxygen is reduced to get hydrogen. In this way, the concepts of oxidation and reduction have been expanded. The oxidation reaction is to obtain oxygen or lose hydrogen, and the reduction reaction is to lose oxygen or obtain hydrogen. Although this concept is superficial, it still has not lost its meaning to this day. Many organic chemical and biochemical redox reactions are often more directly measured in terms of hydrogen loss and hydrogen generation. For example, in photosynthesis, water is oxidized to lose hydrogen and carbon dioxide is reduced to hydrogen. The concept of oxidation and reduction was later extended to the reactions of non-metals other than oxygen, such as chlorine and sulfur. The FeCl2 solution is easily oxidized to FeCl3 in the air, which is an oxidation reaction. 12FeCl2 + 6H2O + 3O2 = 8FeCl3 and 10Fe (OH) 3 However, FeCl2 can also easily react with Cl2 to form FeCl3. 2FeCl2 + Cl2 = 2FeCl3 The essence of these two reactions was studied and the relationship between oxidation, reduction and electron transfer was found. The reaction that loses electrons is an oxidation reaction, and the reaction that gets electrons is a reduction reaction. The phenomenon that redox reactions must occur at the same time is naturally understood more deeply, because the electrons lost by the reducing agent must be obtained by the oxidant at the same time. For redox reactions of ionic compounds, electrons are completely lost or completely acquired. However, for covalent compounds, there are electron shifts in the redox reaction, but they have not been completely lost or obtained, so it is more reasonable to use the oxidation number. For example, the product of the reaction H2 + Cl2 = 2HCl is a covalent compound. The electrons of the hydrogen atom have not been completely lost, and the electrons of the chlorine atom have not been completely obtained. However, the formed electron pair deviates from hydrogen and favors chlorine. In this way, an increase in the oxidation number is oxidation, and a decrease in the oxidation number is reduction. In redox reactions, generally, the increase in the oxidation number of one element is always equal to the decrease in the oxidation number of another element. Oxidant: The oxidizing and reducing oxidant of the substance is easy to get electrons and has oxidizing property. Reducing agents are prone to losing electrons and have reducing properties. The so-called oxidizing ability refers to the ability to oxidize other elements, that is, the ability to seize electrons; the reducing ability refers to the ability to reduce other elements, that is, the ability to lose electrons. Generally speaking, a strong oxidant has a strong oxidizing property and is easy to be reduced by itself; a strong reducing agent has a strong reducing property and is easy to be oxidized by itself. Atoms of metal elements are prone to losing electrons, so they are reducing. The more active the elemental element of the metal element, the stronger the reducing agent, and the stronger the reducing property. It can be seen that the strength of the element's metallicity is consistent with its reducing strength. The active sequence of common metals, that is, the reducing sequence. Many atoms of non-metallic elements are prone to get electrons, so they are oxidizing. The more active the simple substance of the non-metal element is, the stronger the oxidant, the stronger the oxidizing property. It can be seen that the non-metallic strength of an element is consistent with its oxidative strength. Because the strength of the metal and non-metallic elements of the element correspond to the reducing and oxidizing strength of the element, respectively, the periodic table of the element reflects the change law of the metallic and non-metallic elements, and also reflects the reducing ability of the element The change law of oxidation.