Understanding Hydrolysis, Types, Benefits, Formulas, and Examples of Problems

Hydrolysis is one of the meanings of simple chemical reactions that most often occur in our lives. This hydrolysis reaction is a reaction that involves water molecules in the breakdown of compounds. In humans, the process of hydrolysis occurs in the process of digestion of food, where food that has entered the digestive system will be digested by organs but will begin with hydrolysis with water molecules in the body.

In chemistry, very many chemical processes that occur with this hydrolysis reaction. In this article we will discuss about the definition of hydrolysis reaction, types, benefits, formulas, and examples of questions and their answers.

table of contents

  • Hydrolysis
    • Definition of Hydrolysis Reaction
    • Salt hydrolysis
    • Hydrolysis Reactions
      • Partial Salt Hydrolysis (Strong Weak-Acid)
      • Partial Salt Hydrolysis (Strong and Weak Acid)
      • Total Salt Hydrolysis (Weak Acid-Weak Acid)
    • Benefits of Hydrolysis Reactions
    • Examples of Hydrolysis Problems and Answers
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The hydrolysis reaction is very useful in chemistry and biology. Biological applications for this hydrolysis process such as in metabolism that occurs in organisms or living things. The most essential thing in biology that involves the hydrolysis reaction is the breakdown of ATP which is a major source of energy for the human body so that ATP can be used.

In chemistry, hydrolysis reactions are widely used in industry to break down certain chemical structures into fractions or simpler parts. In general, organic chemical compounds have different pathways for each compound to undergo hydrolysis using water.

Definition of Hydrolysis Reaction

The definition of hydrolysis itself is one type of reaction to the decomposition of a substance by using water as a medium to break the bond of that substance. In Greek, hydrolysis comes from the word hydro which means water and lysis which means ” breaking bonds “. So that hydrolysis can be interpreted as an action to break down various kinds of chemicals using water.

Hydrolysis is the opposite of a condensation synthesis reaction which is a process in which two molecules join together to form a more complex molecule by releasing water. To distinguish this very easily, the hydrolysis reaction requires water while the condensation reaction produces water. Water or H 2 O will undergo fragmentation into hydrogen ions (H + ) and hydroxide ions (OH  ) which will play a role in this hydrolysis reaction.

Salt hydrolysis

The simplest example of hydrolysis is the process of dissolving salt in water. Salts like NaCl are examples of compounds that dissolve easily in water. When a salt is added to water, the NaCl will ionize or dissociate in water into sodium ions (Na + ) and chloride ions (Cl  ).

The meaning of sodium ions will be more attracted to negative ions from water, namely hydroxide ions, while chloride ions will be attracted to hydrogen ions from water.

The basic equation of the hydrolysis reaction can be described as follows


AB is the starting material that reacts with HOH or H 2 O, namely water, the result of this reaction is AH and also BOH which is the result of hydrolysis. But this reaction can also take place in the opposite direction called a condensation reaction.

Hydrolysis Reactions

The hydrolysis reaction can take place with some initial chemicals or reactants. Based on the type of initial reactants, hydrolysis can actually be divided into many types, but this time it will be discussed only the type of salt hydrolysis because the hydrolysis of salt is the most widely applied in chemistry;

Partial Salt Hydrolysis (Strong Weak-Acid)

Partial hydrolysis occurs when a salt formed from the reaction of a weak acid and a strong base is dissolved in water, so what happens is that the cation of a base cannot be hydrolyzed, whereas a strong acid anion will undergo a hydrolysis process. Because not all parts are hydrolyzed, it is said that the process is partial hydrolysis. For example the formation of salt:

In this reaction, the salt solution contains sodium ions and acetate ions. Sodium ions as conjugated acids from strong bases have no influence on the acidity of the solution. However, acetate ions as a conjugate base of weak acids react with water and increase the pH of the solution to become a base.

The equivalence constant for this reaction is the ionization constant Kb for the base CH 3 COO  . The Kb value can be calculated based on the value of the water ionization constant (Kw) and Ka.

With M is the concentration of salt.

Partial Salt Hydrolysis (Strong and Weak Acid)

This hydrolysis occurs when salts derived from strong acids and weak bases are dissolved in water. For example, when an ammonium chloride salt (NH 4 Cl) is formed from the reaction of a weak base of ammonia with a strong acid HCl:

The solution contains ammonium ions (NH + ) and chloride ions (Cl  ). Where the chloride ion has no influence on the acidity of the solution even though HCl is a strong acid. However, the ammonium ion which is the conjugate acid of ammonia reacts with water to form a hydronium ion (H 3 O + ) which gives an acidic atmosphere to the solution.

The equilibrium constant for this reaction is also the same as the ionization constant called Ka for NH + acids .

With M is the concentration of salt.

Total Salt Hydrolysis (Weak Acid-Weak Acid)

In contrast to the partial hydrolysis that has been discussed, the salt produced from the reaction between a weak acid and a weak base when dissolved into water will cause total hydrolysis. This is because both positive ions from weak bases and negative ions from weak acids allow hydrolysis to occur.

For example, the reaction between acetic acid which is a weak acid and ammonium hydroxide which is a weak base produces ammonium acetate salt and releases water.

CH 3 COOH + NH 4 OH → CH 3 COONH 4  + H 2 O

In water, either anion CH 3 COO  and the cation NH + ammonium ASTAT can be hydrolyzed with each produces alkaline and acid:

CH 3 COO    + H 2 O CH 3 COOH + OH 

NH +   + H 2 O NH 4 OH + H +

The equilibrium constant or hydrolysis constant in this reaction is called Kh which is different from partial hydrolysis.

Benefits of Hydrolysis Reactions

This hydrolysis reaction is widely applied in daily life, here are some examples of the benefits of hydrolysis in life:

  1. Hydrolysis plays a role in the formation of table salt (NaCl) which is a reaction between strong bases and strong acids. This kitchen salt is widely used as a flavoring ingredient in food.
  2. In agriculture, hydrolysis is also widely applied in the working principle of fertilizers such as (NH 4 ) 2 SO 4 which is able to reduce soil pH so that it is suitable for growing certain crops.
  3. In the human digestive system, hydrolysis also plays an important role in the digestive process. Water plays a role in breaking down compounds from food into simpler compounds so that the body can digest.

Examples of Hydrolysis Problems and Answers

To make it easier to understand the various series of explanations above, the following are examples of questions and discussions about hydrolysis. Among others;

  1. Determine the pH of 0.05 M ammonium chloride solution with NH +Ka is 5.65 x 10 -10


  • Reactions that occur: NH + + H 2 O ⇌ NH 3 + H 3 O +
  • The formula of Ka NH +

Enter the available numbers in the equation above with unknown = X

Since the reaction constants between NH 3 , H 3 O + and NH + are 1 or the same, all three have the same concentration, X.

  • Furthermore, the pH can be calculated by pH = – log [H + ]
  1. What is the pH of 0.1 M of methyl ammonium chloride solution with Ka CH 3NH +2.7 x 10 -11


  • Determine the chemical reaction
  • The equation Ka of CH 3 NH +


  • Reactions that occur: NH + + H 2 O ⇌ NH 3 + H 3 O +
  • The formula of Ka NH +

Well, that was the description of the discussion that we can do for you, relating to the understanding of hydrolysis , types, benefits, calculation formulas, and examples of questions and their answers. I hope this helps.


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