What is selenious acid?

Selenious acid

In the field of chemistry there are many types of acids, these are a type of compound that has the ability to release hydrogens the moment they come into contact and dissolve in water . One of these types of acids is known by the name of selenious acid which is also known by the name of selenous acid , an acid that can become dangerous for humans causing serious health problems .

Selenious acid |  What is it, characteristics, structure, properties, uses 

What is selenious acid?

Selenious acid is a type of inorganic compound analogous to sulfurous acid , which is also a primary oxo acid of selenium . It is a weak acid that can also crystallize, acquiring the form of a white solid.

  • Selenious acid characteristics
  • Structure
  • Formula
  • Nomenclature
  • Selenious acid physical properties
  • Chemical properties
  • Obtaining
  • Uses of selenium acid
  • Risks

Selenious acid characteristics

Among its main characteristics are the following:

  • It is a white crystalline solid very similar to sand.
  • When it is in direct contact with humans, it can produce a large number of acute side effects and chronic effects that damage health.
  • It is a crystal that has no color.
  • It can decompose the moment it is heated , producing a large amount of toxic smoke .
  • Selenic acid decomposes on heating producing selenium dioxide which is toxic and volatile.


The structure of selenious acid is of the hexagonal crystalline type .

Selenious acid |  What is it, characteristics, structure, properties, uses


Selenious acid is made up of hydrogen , ions, and selenite . The chemical formula of selenious acid is as follows: H2O3Se


The nomenclature of selenious acid can be done in three different ways:

  • Systematic nomenclature : in this case it is named as hydrogen trioxoseleniate (IV).
  • Nomenclature stock : using this type of nomenclature, is named as follows way trioxoselénico acid (IV)
  • Traditional nomenclature : it is known by the name of selenious acid.

Selenious acid physical properties

Among its main physical properties are the following:

  • It has a white color .
  • When it is dissolved in water, it produces a totally colorless solution .
  • It is an acid that has no odor .

Chemical properties

The chemical properties of this acid are mentioned below:

  • It has a molecular weight of 97 g / ml .
  • Its melting point is 70 ° C.
  • It has a density of 004 g / ml .
  • Its boiling point is between 176,000 and 177,000 mm Hg.
  • It is quite soluble in water and ethanol but cannot mix with ammonia.
  • When heated, it decomposes into selenium dioxide which is toxic and highly volatile.
  • May react exothermically with many reducing agents.
  • It is a stable compound but it is also classified as poisonous .
  • Reacts with bases to form selenites .
  • Its molar mass is 128.97 g / mol.


Selenious acid can be obtained by following a series of steps to prepare it. First to selenium dioxide is added to the water and then proceeds to perform the separation of solids and liquids , the washing of the product, drying , and finally is allowed to cool to achieve obtain the selenious acid.

Uses of selenium acid

Selenious acid has a wide variety of uses. Perhaps the main one of them is to be able to change the original color that the steel has through a process known as cold bleaching. It is also used to change the color of brass and bronze . It is used as a type of oxidizing agent and has a special use in the manufacture of Mecke’s reagent , which is used to control drugs. When in its isotopic form it can be used as a pharmaceutical radioactive and as a source of selenium it is also used as a nutritional supplement. when administered in a totally controlled manner and in extremely low amounts.


Selenious acid is highly toxic and has the ability to produce great hazards when it comes into contact with the skin and eyes. It is extremely irritating and even overexposure to acid can lead to death . When a person is continuously exposed to selenious acid, they can have serious health problems including damage to several of their organs.

Being in contact with selenium acid can cause skin rashes , stomach pain , extreme tiredness , loss of hair and nails . It is important to mention that this type of acid can be absorbed very quickly in the intestine and also dangerously accumulates in the liver and kidneys , damaging these organs. Problems with the central nervous system can also occur causing seizures , drowsiness , headache in the front and death from respiratory depression.

If the product manages to enter the bloodstream through a cut or injury, a series of systemic injuries can occur that affect the entire body. The inhaling dust acid also generate a number of toxic effects and respiratory problems .

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