Salts Types Hydrolysis - Examples, Classification, Difference, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:50 PM IST

What is a SALT?

A chemical compound formed by the combination of positive ions called actions and negative ions called anions is called salt. The product obtained by this fusion of cations and anions has a net charge of zero i.e. a neutral compound. The ionic components contributing to the formation of salt can be polyatomic, monoatomic, organic or inorganic. The chemical composition of salt represents a 1:1 ratio of sodium and chloride ions. Salt is the general term used to describe a substance or a chemical compound formed as a result of a reaction taking place between an acid and a base.

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What is a SALT?
Calcium Chloride-
Potassium Dichromate -
Sodium bisulphate -
Copper Sulphate-
Classification of salt:
Difference between Complex salts and double salts :-

The cation and an anion are the constituent elements of salt. This reaction between acid and base is called a neutralization reaction. Salt is made up of cation and anion as described above. A chemical product resulting from a neutralization reaction by replacing one or more than one hydrogen atom of an acid with other groups or elements capable of ionizing in the solution. Salts being an ionic compound tend to dissociate into cations and anions in the solution.

The cation part is always a metal cation or is derived from ammonium (NH₄+).Salts are named by mentioning the positively charged ion or cation part first followed by negatively charged ion or anion. The salt deposits are mined to get table salt from it. Table salt is processed which leads to elimination of contaminants and minerals present in it. It is further iodized by adding iodine content. The nutritional value of table salt and sea salt is more or less the same. But often, sea salt is most preferred over table salt being healthier. Salts containing an organic ion are termed as organic salts.

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Organic salt examples are – sodium acetate, sodium laurate.

Examples of salt:- Salt chemical name:- Sodium Chloride

The molecular formula of salt – NaCl.The salt water reaction is also termed hydrolysis and is represented as follows-

NaCl +H₂O → NaOH + HCl

Hydrolysis is the reverse of neutralization reaction wherein salt and water are products obtained in the reaction between acid and base.

Sodium chloride

Sodium chloride or table salt consists of sodium cation and chloride anion having a salt formula as NaCl. It is a major component used by everyone in day to day activities and in any interesting area of concern. Sodium hydroxide is neutralized by hydrochloric acid resulting in salt formation. The desired salt is obtained after the evaporation of the water content present in it. This strong acid and strong base reaction lead to the formation of an electrically neutral compound, NaCl being the salt chemical formula.

HCl + NaOH NaCl + H₂O

Calcium Chloride-

The calcium chloride and Sodium chloride salt are similar because of their white colour.

It is commonly used for the removal of ice from the road.

Potassium Dichromate -

This chemical comprises potassium, chromium and oxygen.

It is used as an oxidising agent in many chemical reactions.

It is toxic and must be handled cautiously.

Chromium is a potent carcinogen that can cause serious injuries if this is spilt on the skin.

Sodium bisulphate -

It is also specified as dry acid. It is prepared from sulfuric acid. It helps in decreasing the pH of pools and spas. It is hazardous for skin if mishandled.

Copper Sulphate-

Copper Sulphur and oxygen are the main components.

It is also used as an electrolyte in cells.

Physical and chemical properties of salt –

Crystalline, bitter and hard chemical substances.
Salt solution or saline solution is capable of conducting electricity.
It is odourless having a salty taste. Salts are present in cube forms.
Salt is water-soluble
Salts are slightly soluble in alcohol but insoluble in a concentrated solution of hydrochloric acid (HCl).
Salts are capable of absorbing moisture content from the surrounding i.e they are Hygroscopic.

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Classification of salt:

How many types of salt are there?

There exist five types of salts as follows:

Normal Salt:

Electrically neutral salts are called Normal salts. Normal salts lack replaceable hydroxyl or hydrogen in their chemical formula. The hydrogen ions are replaced by metallic ions in the reaction. Neutral salt examples are: NaCl, KNO₃, etc.

Basic Salt:

When a partial or incomplete neutralization reaction takes place between acid and a base being weak and strong respectively, basic salts are obtained.

Eg: Calcium Carbonate (CaCO₃), Sodium Acetate (NaOOCCH₃), etc.

Acidic salt:

The acidic salt definition is as follows-

A neutralisation reaction between a strong acid and weak base results in the formation of acidic salt. NH₄Cl is obtained as a reaction product between strong acid – HCl and weak base – NH₃. An example of acidic salt is ammonium chloride.

Mixed salt:

Two salts of mixed proportions make a mixed salt. These two salts share a common cation or anion. A mixed salt example is CaOCl₂.

Double Salt definition:

Salts comprising more than one anion or a cation is called double salt. They ionize as two different salts when dissolved in water.

Eg: Potash alum – K₂SO₄.AL₂(SO₄)₃.24H₂O

Ammonium ion – (NH₄)₂Al₂(SO₄)₃.24H₂O

Mohr’s Salt – FeSO₄(NH₄)₂SO₄.6H₂O

Double salts always exist in a solid-state and are water-soluble. Isomeric properties are not shown by them. They usually contain one or more molecules of crystal water.

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Hydrated Salt :-

A hydrated salt is a crystalline salt that is associated with a certain number of water molecules. Hydrated salts occur naturally all over the globe i.e. in freshwater bodies, groundwater bodies, rocks, etc. Hydrated salts mostly exist in crystalline form. Hydrate salt formation takes place due to exposure of salts to air allowing the formation of bonds with water molecules in the surrounding. Give two examples of hydrated salts. Plaster of Paris (POP) and gypsum salts are two examples. Epsom salts are a very familiar example of hydrated salts.

Epsom salt's general formula is MgSO₄.7H₂O and its chemical name is Magnesium Sulphate. The human body requires certain chemicals containing salt, but it might not be possible to absorb or ingest salt-containing health products through our diets alone. Hence, people are sometimes advised to take healthy baths at places where these hydrated salts are available. It is also used as a pain reliever and healing agent. Epsom salts are beneficial for maintaining blood pressure and blood circulation and also helps in digestion.

Complex Salt:-

The salts containing one or more than one complex ions with metal at the centre are defined as complex salts.

Complex salts are different from double salts and simple salts.

Examples of complex salts are as follows:-

Potassium ferricyanide [K₃Fe(CN)₆]

Potassium argentocyanide KAg(CN)₂

Complex salts are unable to dissociate completely into ions. When potassium ferricyanide is dissolved in water it dissociates into 4K⁺ and [fe(CN)₆]^- leading to formation of five ions.

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Difference between Complex salts and double salts :-

Combination of two different salts leads to formation of double salt compounds.

Whereas a chemical compound with a central metal atom forming bonds with the ligands surrounding it are called a complex salt compound.

Double salt consists of two salt compounds and complex salts contain one or more than one complex ion.
Complex salts are not capable of dissociating completely into ions but double salt compounds can completely dissociate into ions.
Complex ions are hard to analyze but it is much easier to analyze the ions produced due to the dissociation of double salt compounds.
Double salts lack coordinate bonds but complex salts consist of coordinate bonds between centrally placed metal atoms and the ligands surrounding.
Double salts tend to lose their identity in solution but complex salts can retain their identity.

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NCERT Chemistry Notes:

Frequently Asked Questions (FAQs)

1. How many types of salts are there?

There exist 5

types of salts namely Acidic salt, Basic salt, Double salt, Mixed salt, Normal salt.

2. How does the basic salt formation take place?

The neutralization reaction between a strong base and weak acid leads to the formation of basic salt.

3. What is a neutralization reaction?

The reaction between an acid and a base giving salt and water is termed a neutralization reaction.

4. Give any two properties of salt.

Following are the properties-

Salts are crystalline, chemical and hard ionic substances.

They are odourless and capable of conducting electricity.

5. What is the nature of salt?

The nature of salt is ionic consisting of cation and an anion having a crystalline structure.

6. How does the hydrolysis of a salt affect its conductivity in solution?

Salt hydrolysis can affect conductivity by:

7. What role does salt hydrolysis play in the formation of stalactites and stalagmites?

Salt hydrolysis plays a crucial role in the formation of stalactites and stalagmites. Calcium carbonate in limestone undergoes hydrolysis in the presence of slightly acidic rainwater (due to dissolved CO2). This process slowly dissolves the limestone, allowing it to be redeposited as calcium carbonate formations in caves.

8. How does the concept of salt hydrolysis apply to the production of gastric acid in the stomach?

Salt hydrolysis is relevant to gastric acid production in two ways:

9. What is the relationship between salt hydrolysis and the concept of Lewis acids and bases?

Salt hydrolysis can be understood in terms of Lewis acid-base theory:

10. What is meant by the term "neutral salt"?

A neutral salt is a salt that does not undergo hydrolysis when dissolved in water. It is typically formed from a strong acid and a strong base, and its aqueous solution maintains a pH of 7.

11. What is salt hydrolysis?

Salt hydrolysis is the reaction of a salt with water, resulting in the formation of an acidic or basic solution. This occurs when the anion or cation of the salt reacts with water molecules, producing hydrogen or hydroxide ions.

12. How can you predict whether a salt will form an acidic, basic, or neutral solution?

To predict the nature of the solution:

13. Why do some salts undergo hydrolysis while others don't?

Salts undergo hydrolysis when they are formed from a weak acid and/or a weak base. The ions from these weak acids or bases can react with water, causing a change in pH. Salts formed from strong acids and strong bases do not undergo hydrolysis because their ions do not react with water.

14. How does the concentration of a salt solution affect its pH during hydrolysis?

Increasing the concentration of a salt solution generally enhances the effect of hydrolysis on pH. For salts that hydrolyze to form basic solutions, higher concentrations lead to higher pH values. For salts that form acidic solutions, higher concentrations result in lower pH values.

15. What is meant by the term "degree of hydrolysis"?

The degree of hydrolysis refers to the fraction of salt molecules that undergo hydrolysis in solution. It's expressed as a percentage or a decimal and indicates how extensively the salt reacts with water. A higher degree of hydrolysis results in a greater deviation from neutral pH.

16. Why does aluminum chloride solution have a lower pH than sodium chloride solution?

Aluminum chloride undergoes cationic hydrolysis, where Al3+ ions react with water to produce H+ ions, lowering the pH. Sodium chloride does not undergo hydrolysis as it's formed from a strong acid and strong base, maintaining a neutral pH.

17. Can you explain why the pH of a salt solution might change over time?

The pH of a salt solution can change over time due to:

18. Why is the hydrolysis of iron(III) chloride more extensive than that of iron(II) chloride?

Fe3+ ions have a higher charge density than Fe2+ ions, making them stronger Lewis acids. This allows Fe3+ to interact more strongly with water molecules, pulling them apart more effectively and releasing more H+ ions into the solution, resulting in more extensive hydrolysis and a lower pH.

19. How does the presence of other ions in solution affect salt hydrolysis?

Other ions can affect salt hydrolysis through:

20. What is the difference between hydrolysis and dissociation?

Hydrolysis involves the reaction of a substance with water, often resulting in the formation of new compounds. Dissociation is the separation of a compound into its constituent ions when dissolved in water, without any chemical reaction with water molecules.

21. Can you explain why ammonium chloride solution is acidic?

Ammonium chloride undergoes cationic hydrolysis. The ammonium ion (NH4+) reacts with water to produce hydronium ions (H3O+), resulting in an acidic solution with a pH less than 7.

22. How does the strength of the parent acid or base affect salt hydrolysis?

The strength of the parent acid or base determines the extent of hydrolysis. Salts from weaker acids or bases undergo more extensive hydrolysis, resulting in a greater change in pH. Salts from stronger acids or bases undergo less hydrolysis or none at all.

23. How does temperature affect salt hydrolysis?

Increasing temperature generally increases the extent of hydrolysis. This is because higher temperatures provide more energy for the hydrolysis reaction to occur, leading to a greater production of hydrogen or hydroxide ions.

24. Why does sodium carbonate solution have a higher pH than sodium bicarbonate solution?

Sodium carbonate (Na2CO3) produces two hydroxide ions per molecule during hydrolysis, while sodium bicarbonate (NaHCO3) produces only one. This results in a higher concentration of OH- ions in the sodium carbonate solution, leading to a higher pH.

25. How does the hydrolysis of a salt affect its solubility?

Salt hydrolysis can affect solubility by:

26. What is the connection between hydrolysis and acid-base indicators?

Acid-base indicators are weak acids or bases that change color at specific pH ranges. When a salt undergoes hydrolysis, it changes the pH of the solution. This pH change can cause the indicator to change color, allowing us to visually determine whether the hydrolyzed salt solution is acidic, basic, or neutral.

27. How does the hydrolysis of potassium fluoride compare to that of potassium chloride?

Potassium fluoride undergoes slight anionic hydrolysis because F- is a weak base:

28. How does the hydrolysis of a salt affect its freezing point depression?

Salt hydrolysis can affect freezing point depression by:

29. Why is understanding salt hydrolysis important in the context of acid-base titrations?

Understanding salt hydrolysis is crucial in acid-base titrations because:

30. Why is the hydrolysis of sodium bicarbonate less basic than that of sodium carbonate?

Sodium bicarbonate (NaHCO3) produces one OH- ion per molecule during hydrolysis:

31. How does the hydrolysis of sodium acetate affect the pH of the solution?

Sodium acetate undergoes anionic hydrolysis. The acetate ion reacts with water to produce hydroxide ions, resulting in a basic solution with a pH greater than 7.

32. What is the significance of the hydrolysis constant (Kh)?

The hydrolysis constant (Kh) is a measure of the extent of hydrolysis. A larger Kh value indicates more extensive hydrolysis, resulting in a greater deviation of pH from neutrality. It helps quantify the strength of the hydrolysis reaction.

33. How does the common ion effect influence salt hydrolysis?

The common ion effect suppresses hydrolysis by increasing the concentration of one of the ions involved in the hydrolysis equilibrium. This shifts the equilibrium away from hydrolysis, reducing its effect on pH.

34. How does the hydrolysis of aluminum ions contribute to the acidity of soil?

Aluminum ions (Al3+) in soil undergo hydrolysis, producing H+ ions:

35. Why do some salts, like sodium chloride, not change the pH of water when dissolved?

Sodium chloride is formed from a strong acid (HCl) and a strong base (NaOH). Neither Na+ nor Cl- ions react with water molecules, so they don't produce H+ or OH- ions. Therefore, the solution remains neutral with no change in pH.

36. How does the concept of hydrolysis apply to soap and detergent chemistry?

Soaps and detergents are salts of fatty acids. When dissolved in water, they undergo hydrolysis to produce slightly basic solutions. This alkalinity helps in the cleaning process by breaking down oils and fats, and also helps to neutralize acidic dirt and grime.

37. How does the hydrolysis of potassium cyanide differ from that of ammonium cyanide?

Potassium cyanide undergoes anionic hydrolysis, producing OH- ions and a basic solution. Ammonium cyanide undergoes both cationic and anionic hydrolysis, but since CN- is a stronger base than NH4+ is an acid, the solution is still basic, though less so than potassium cyanide.

38. How does the hydrolysis of a polyprotic acid salt, like Na2CO3, differ from that of a monoprotic acid salt?

Na2CO3 undergoes stepwise hydrolysis, first producing HCO3- and then CO32-. Each step can contribute to the production of OH- ions, potentially leading to a more basic solution compared to salts of monoprotic acids, which undergo only one hydrolysis step.

39. How does the hydrolysis of ethyl acetate differ from salt hydrolysis?

Ethyl acetate hydrolysis is the breakdown of an ester into an alcohol and an acid in the presence of water. Unlike salt hydrolysis, it doesn't involve ions and doesn't necessarily change the pH. Salt hydrolysis involves the reaction of salt ions with water, often resulting in pH changes.

40. What are the three main types of salt hydrolysis?

The three main types of salt hydrolysis are:

41. What is the role of Le Chatelier's principle in salt hydrolysis?

Le Chatelier's principle helps explain how the hydrolysis equilibrium shifts in response to changes in conditions. For example, adding more salt to a solution undergoing hydrolysis will shift the equilibrium to produce more hydrolyzed products, affecting the pH.

42. Can you explain the concept of a buffer solution in relation to salt hydrolysis?

A buffer solution resists changes in pH when small amounts of acid or base are added. Some hydrolyzed salt solutions, like those containing a weak acid and its conjugate base (e.g., acetic acid and sodium acetate), can act as buffers due to the equilibrium established during hydrolysis.

43. What is the relationship between Ka, Kb, and Kw in salt hydrolysis?

For a salt formed from a weak acid (HA) and weak base (BOH): Kh = Kw / (Ka * Kb)

44. What is the significance of hydrolysis in biological systems?

Hydrolysis is crucial in biological systems for:

45. What is the role of hydrolysis in the weathering of rocks and minerals?

Hydrolysis plays a significant role in rock weathering by:

46. How does the hydrolysis of ammonium acetate differ from that of sodium acetate or ammonium chloride?

Ammonium acetate undergoes both cationic (NH4+) and anionic (CH3COO-) hydrolysis. The NH4+ produces H+ ions while CH3COO- produces OH- ions. The pH of the solution depends on the relative strengths of these ions. Sodium acetate only undergoes anionic hydrolysis (basic), while ammonium chloride only undergoes cationic hydrolysis (acidic).

47. How does the hydrolysis of ammonium carbonate differ from its component salts?

Ammonium carbonate ((NH4)2CO3) undergoes both cationic and anionic hydrolysis:

48. Why is the pH of a solution of sodium acetate and acetic acid relatively stable?

A solution of sodium acetate and acetic acid forms a buffer system. The acetate ion from sodium acetate undergoes hydrolysis: