chemical phenomena



We explain what chemical phenomena are, their characteristics, classification and examples. Also, what are physical phenomena.

Many chemical phenomena, such as combustion, are irreversible.

What are chemical phenomena?

Chemical phenomena are processes thermodynamic in which two or more substances, called reactants, change their molecular structure and generate new substances, called products. The reactants or products can be elements or chemical compounds. Chemical phenomena are also called chemical reactions or chemical changes, terms that are synonyms.

In chemical phenomena there is a significant change in matter, which is never the same at the beginning of the reaction as at the end, in such a way that it is usually irreversible and not always visible to the naked eye. On the other hand, the amounts of matter Y Energy involved before and after the chemical reaction occurs, they always remain constant.

The chemical reactions are common in our day to day and many of them are key in the manufacture of products, obtaining energy and other processes of importance for the society.

Types of chemical reactions

With heat, sucrose can be broken down into fructose and glucose.

Before showing the different types of chemical reactions, it is important to know some of the symbols used to represent these reactions using chemical equations:

Chemical reactions are classified, first of all, according to the types of chemical compounds they involve. We will thus have organic and inorganic chemical reactions, and each type is classified independently:

  • Inorganic reactions. They are those that involve inorganic compounds, and can be classified:
    • According to the rearrangement of the atoms of the reactants when they are transformed into products:
      • Synthesis or addition reactions. Two reagents combine with each other to result in a different substance.
      • Decomposition reactions. One substance reacts with another and breaks down into its simplest components.
      • Simple substitution or displacement reactions. One compound or element takes the place of another, within a larger or more complex compound, replacing it and leaving it free.
      • Double substitution reactions. Two reagents exchange chemical compounds or elements simultaneously.
    • According to the energy that is exchanged during the reaction:
      • Endothermic reactions. They are reactions that absorb heat when they occur.
      • Exothermic reactions. They are reactions that release heat when they occur.
      • Reactions that need light to occur. They are those that absorb light when they occur.
      • Reactions that emit light when they occur. They are those that when they occur emit energy in the form of light.
    • According to the reaction speed:
      • Quick reactions. They are reactions that occur in a very short time.
      • Slow reactions They are reactions in which the formation of products from certain reagents takes a long time.
  • Organic reactions. Organic reactions depend on the type of organic compound in question, since each functional group has a range of specific reactions: alkanes, alkenes, alcohols, ketones, aldehydes, etc.

Examples of chemical phenomena

Rust and corrosion are chemical phenomena.

Any chemical reaction is a good example of chemical phenomena, even those that occur inside our bodies. We can mention some simple cases:

  • Oxidation. We can see this phenomenon in metals, especially in saline environments (since salt acts as a catalyst, accelerating the reaction between oxygen and metal), and consists of the formation of a layer of rust (or oxide) on the surface of the oxidized metal. It also occurs inside our bodies, since with the oxygen that we take at breathe, we then proceed to oxidize glucose molecules, getting chemical energy.
  • Combustion. It is a rapid oxidation reaction that can cause fire. For example, when we light a paper with a match and watch it turn to ashes. These types of reactions involve a combustible material (paper) and a oxidizer (oxygen from air) in the presence of an increase in temperature.
  • Corrosion. It is the result of an electrochemical reaction of a material (generally a metal) with the environment that surrounds it. When a substance corrodes, it is deteriorated and can wear out, break or break. Materials such as wood, ceramics, some plastics and even human skin, can also suffer corrosion.
  • The production of salts. When they mix a acid and a metal, as in the case of spillage of the contents of some batteries old inside the compartment of a television remote control, a salt of some kind is produced, depending on the metal and the acid.

Chemical phenomena and physical phenomena

A physical change can be as simple as a change from a solid to a liquid state.

The difference between physical phenomena and chemical phenomena has to do with the type of change that occurs in matter. Physical phenomena are related to changes of form and state in which the substance remains chemically the same, that is, they do not involve chemical reactions.

For example, if we freeze Water, we can turn it into a solid (ice) without ceasing to be made up of hydrogen and oxygen.

Instead, chemical phenomena reorganize the structure molecular of matter, forming and breaking chemical links between the atoms and creating new substances. This is because a chemical reaction occurs, generally irreversible, in which substances other than the initial ones are obtained.

For example, after burning a piece of paper and turning it to ashes, we cannot restore it to its original condition.

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