What is hydrolysis?


Hydrolysis means destruction , decomposition or alteration that a certain chemical substance undergoes by water. When studying aqueous solutions of electrolytes , the term is applied to the reactions of cations with water to produce a weak base, or in other cases, to those of anions to produce a weak acid . It is important to mention that the degree of hydrolysis is the fraction of the ion that reacts with water.

What is hydrolysis?

It is the chemical decomposition that occurs in substances by water , which depends on the chemistry, solubility , pH and the oxidation-reduction or redox potential of a certain compound.

  • Definition
  • Types
  • Chemical hydrolysis
  • Acid hydrolysis
  • Enzymatic hydrolysis
  • Alkaline hydrolysis
  • Degree of hydrolysis
  • Importance
  • Examples


Hydrolysis involves the reaction of an organic chemical using water to form two or more new substances , in other words hydrolysis usually means the splitting of chemical bonds through the addition of water. In fact, it can be the opposite of a condensation reaction in which two molecules join together into a larger one and expel a molecule of water. This hydrolysis mechanism is used primarily in the manufacture of alcohols such as ethanol, glycols such as ethylene glycol, propylene glycol and propylene oxide.


There are basically four different types of hydrolysis, which are as follows:

  • Hydrolysis of strong acid-strong base salt : in this group let us mention, for example, NaCl. This salt comes from HCl and NaOH, therefore Na + and Cl-, will be respectively weak. Na + + H2O there is no reaction Cl- + H2O there is no reaction Therefore the pH will be neutral.
  • Hydrolysis of weak acid-strong base salt such as : for example, NaCN (Na + CN-), which comes from HCN (weak acid) and NaOH (strong base), therefore Na + will be weak and CN- strong. Na + + H2O no reaction CN- + H2O HCN + OH-.
  • Strong acid-weak base salt hydrolysis : such as NH4Cl (NH4 + Cl-) that comes from HCl (strong acid) and NH3 (weak base), so NH4 + will be strong and Cl- will be weak. Cl- + H2O no reaction NH4 + + H2O NH3 + H3O +.
  • Hydrolysis of weak acid-weak base salt : for example, NH4CN (NH4 + CN-) that comes from HCN (weak acid) and NH3 (weak base), therefore NH4 + and CN- will be strong. NH4 + + H2O NH3 + H3O +

Chemical hydrolysis

In the area of chemistry , it is a double decomposition reaction where water functions as one of the reactants. Water reactants and hydrolysis products can be neutral molecules or ionic molecules.

Acid hydrolysis

In acid hydrolysis, water can be found acting as an acid or a base , based on the Brønsted-Lowry acid theory . It is a process by which a protic acid is used to catalyze cleavage having a chemical bond by a reaction of nucleophilic substitution by adding water. This term is also used in some occasions to refer to some reactions of nucleophilic action , as for example in the acid catalyzed hydrolysis of nitriles to amides.

It is used for sugars reducers in order to be able to get bio ethanol from the hydrolysis of the bagasse obtained from sugarcane . On some occasions it is used to carry out the enzymatic hydrolysis of glycogen in order to obtain glucose.

Enzymatic hydrolysis

The main function of enzymatic hydrolysis is to produce sugars that can be fermented , such as glucose , through the use of enzymes . These sugars can then be fermented, resulting in bioethanol . The production of this substance from agro-industrial waste with the aim of being used in the biorefinery is a viable alternative in the area of ​​biofuels.

Alkaline hydrolysis

Alkaline hydrolysis is a process that is done with water at temperatures between 150 and 180 degrees Celsius in which Potassium Hydroxide is added , which works as an active agent to decompose biological material such as proteins , nucleic acids , carbohydrates and lipids , in a sterile water- based solution made up of amino acids and sugars. Use pressure to create heat to speed up the process.

Degree of hydrolysis

The degree of hydrolysis is the measure that is generally represented by percentages in which a compound can become ionized or dissolved in water . This number is used mainly to carry out studies on the colligative properties that solutions have and is expressed as the relationship between the dissociated and the initial particles.


Hydrolysis is especially important when it comes to natural esters , such as those found in fats, waxes, animal and vegetable oils . Its mainly technical importance is related to the hydrolysis of fats, cellulose, proteins, esters , sucrose and starch . From the ecological point of view, the hydrolysis of herbicides and other harmful substances stands out as a possibility of detoxification. In addition, hydrolytic processes are under development to take advantage of plastic, wood and paper waste .


Some examples are:

  • The Sodium Chloride NaCl in aqueous solution is hydrolyzed to form sodium ions (Na +) and chloride (Cl-)
  • The Sodium Hydroxide NaOH in aqueous solution is hydrolyzed to form sodium ions (Na +) and hydroxide (OH-)
  • The sulfate Na2SO4 aqueous solution is hydrolyzed to form sodium ions (Na +) and sulfate (SO4-2)
  • The Calcium Chloride CaCl2 aqueous solution is hydrolyzed to form calcium ions (Ca + 2) and chloride (Cl-)

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