Acids, Bases and Salts
The chemical compounds around us can easily be categorised as Acids, Bases and Salts. Acids, Bases and Salts are compounds which occur naturally and can also be created artificially. They are found in various substances including our food. Vinegar or acetic acid is used as a food preservative. Citrus fruits have citric acid and etc.
Other than food they also have a wide variety of uses such as in various industries, manufacturing plants, processing plants, laboratories and others. In this article, we will learn about Acids, Bases, and Salts, their properties, types, uses and others in detail. The image given below shows acid and base which when reacting form salt.
What are Acids?
An acid is a molecule that can contribute an H+ ion while also remaining energetically favourable after losing that ion. e.g. Sulfuric acid (H2SO4), Acetic Acid (CH3COOH), Nitric Acid (HNO3) etc. The image given below shows an acid in its aqueous medium.
Physical Properties of Acid
Acids have specific physical properties and they can easily be distinguished by their physical properties. Some physical properties of acids are:
- Acids have a Sour flavour.
- They turn Blue litmus Red.
- Acid conduct electricity in their aqueous form
Chemical Properties of Acid
Acid has various chemical properties few of the following chemical properties of acids include,
Reaction of acids with metal: When an acid reacts with a metal, it produces hydrogen gas and the corresponding salt.
Metal + Acid → Salt + Hydrogen
Example: When hydrochloride acid combines with zinc metal, it produces hydrogen gas and zinc chloride.
Zn + 2HCl → ZnCl2 + H2
Reaction of acids with metal carbonate: When acids react with metal carbonates, they produce carbon dioxide gas and salts as well as water.
Metal carbonate + Acid → Salt + Carbon dioxide + Water
Example: When hydrochloric acid combines with sodium carbonate, it produces carbon dioxide gas, sodium chloride, and water.
Na2CO3 + 2HCl → 2NaCl + H2O + CO2
Reaction of acid with hydrogen carbonates (bicarbonates): When acids react with metal hydrogen carbonates, they produce carbon dioxide gas, salt, and water.
Acid + Metal hydrogen carbonate → Salt + Carbon dioxide + Water
Example: Sulfuric acid gives sodium sulfate, Carbon dioxide gas and water when it reacts with sodium bicarbonate.
2NaHCO3 + H2SO4 → NaCl + CO2 + H2O
Types of Acids
Acids are classified into different categories, the classification of acids is discussed below in the article.
On the basis of their Occurrence
On the basis of their Occurrence acid are subdivided into two categories
- Natural Acid
- Mineral Acids
Natural acids, often known as organic acids, are acids derived from natural sources. For example Methanoic acid (HCOOH), Acetic acid (CH3COOH), Oxalic acid (C2H2O4), etc.
Mineral acids are acids that are created from minerals. Inorganic acids, man-made acids, and synthetic acids are all examples of Mineral Acids. For example Hydrochloric acid (HCl), Sulphuric acid (H2SO4), Nitric acid (HNO3), Carbonic acid (H2CO3), Phosphoric acid (H3PO4), etc.
On the basis of Concentration
On the basis of Concentration, acids are categorized into two categories
- Strong Acid
- Weak Acid
Strong Acid is an acid that is totally ionized in water and produces (H+). For example Hydrochloric acid (HCl), Sulphuric acid (H2SO4), Nitric acid (HNO3) etc.
A weak acid is one that is partially ionized in water and hence creates a tiny amount of hydrogen ions (H+). For example Acetic acid (CH3COOH), Carbonic acid (H2CO3) etc.
Uses of Acids
Acids have various uses some of the important uses of acid are,
- Vinegar is a diluted solution of acetic acid that has a variety of uses in the home. It’s mostly utilized in the food industry as a preservative.
- Orange and lemon juice contain a significant amount of citric acid. It can also be used for food preservation.
- In batteries, sulfuric acid is commonly utilized. This acid is typically found in the batteries used to start vehicle motors.
- Sulfuric and nitric acid is used in the industrial production of dyes, explosives, paints, and fertilizers.
- Many soft drinks contain phosphoric acid as the main ingredient.
What are Bases?
Bases are chemical compounds that react chemically with acids, they produce salts and hydroxide ions (OH–) in water. For example Potassium hydroxide (caustic potash or KOH), Calcium hydroxide (Ca(OH)2), Sodium hydroxide (caustic soda or NaOH) etc. The image given below shows a base in its aqueous medium.
Physical Properties of Base
Bases have specific physical properties and they can easily be distinguished by their physical properties. Some physical properties of bases are:
- Base has a bitter taste
- Bases are soapy to touch
- Base change red litmus to blue
- Aquaus solution of base conducts electricity
Chemical Properties of Base
Bases have various chemical properties few of the following chemical properties of bases are,
Reaction of Base with Metals: When alkali (base) reacts with metal, salt and hydrogen gas is produced.
Alkali + Metal → Salt + Hydrogen
Example: When sodium hydroxide interacts with aluminium metal, sodium aluminate and hydrogen gas are generated.
2NaOH + 2Al + 2H2O → 2NaAlO2 + 2H2
Reaction of Non-Metallic Oxides with Base: Salt and water are formed when non-metallic oxides react with a base.
Non-metallic oxide + Base → Salt + Water
Example: When calcium hydroxide reacts with carbon dioxide calcium carbonate is formed along with water.
Ca(OH)2 + CO2 → CaCO3 + H2O
Action of Alkalis/Base with Ammonium Salts: Ammonia is produced when alkalis react with ammonium salts.
Alkali + Ammonium salt → Salt + Water + Ammonia
Example: When calcium hydroxide reacts with ammonium chloride, calcium chloride, water, and ammonia are produced.
Ca(OH)2 + NH4Cl → CaCl2 + H2O + NH3
Types of Bases
Acidity, concentration, and degree of ionization are three variables that can be used to classify bases.
Types of Bases Based on Acidity
Acidity in bases is determined by the number of hydroxyl ions present. Based on acidity, bases are classified into three categories:
Mono-acidic bases are those that contain only one hydroxyl ion and interact with only one hydrogen ion. Mono-acidic bases include NaOH, KOH, and others.
Diacidic base is a base with two hydroxyl ions that interact with two hydrogen ions. Ca(OH)2, Mg(OH)2, and other di-acidic bases are examples.
Triacidic base is a type of base that comprises three hydroxyl ions and three hydrogen ions. Triacidic bases include Al(OH)3, Fe(OH)2, and others.
Types of Bases based on their Concentration
Based on their concentration in an aqueous solution, bases are divided into two categories:
Concentrated: The concentration of base in these types of bases is higher in the solution. Concentrated NaOH solution, for example.
Diluted: These types of bases have a lower concentration of base in their aqueous solution. For instance, dilute NaOH, dilute KOH, and so on.
Types of Bases Based on their Degree of Ionization
The degree of ionization of bases in solution can be used to classify them. It’s also known as foundation strength. When dissolved in water, it produces a certain quantity of hydroxyl ions. The degree of ionization distinguishes two types of bases.
- Strong Base
- Weak Base
Strong Base: A strong base is one that dissociates entirely or to a large extent in water. For example, NaOH, KOH, and strong bases.
Weak Base: A weak base is one that does not dissolve entirely or only dissociates to a very little level. For example, NH4OH, and others are weak bases.
Uses of Bases
Base has various uses some of the important uses of the base are,
- Sodium hydroxide is used in the making of paper and soap. Sodium hydroxide (NaOH) is also utilized in the production of rayon.
- Bleaching powder is made from Ca(OH)2, commonly known as calcium hydroxide or slaked lime.
- Calcium hydroxide is used to create dry mixtures for painting and decorating.
- Magnesium hydroxide, popularly known as milk of magnesia, is a laxative that is extensively used. It is also used as an antacid since it decreases excess acidity in the human stomach.
- In laboratories, ammonium hydroxide is a critical reagent.
- Slaked lime can be used to neutralize any excess acidity in soils.
Bases which are easily dissolved in water are called Alkali, in other words, water-soluble bases are called Alkali. For example, NaOH is an alkali as it dissolves in water forming Na+ and OH– ions.
Difference between Alkali and Base
The difference between Alkali and Base can easily be understood with the help of the table given below,
|Water soluble bases are called alkali||Bases do not dissolve in water|
|All alkalis are bases||Not all bases are alkali|
|Alkali releases OH– ions on dissolving in water, they also are proton acceptors.||Bases neutralise the acid in an acid-base neutralization reaction.|
|Example: Potassium Hydroxide (KOH), Sodium Hydroxide(NaOH)||Example: Zinc hydroxide(ZnOH), Copper Oxide(CuO)|
Arrhenius’s Theory of Acid and Base
What is acid, what is base, and what is the difference between acid and base? these questions are nightmares to chemists in the early 15 and 16 centuries. To solve these questions a chemist name Arrhenius came up with a theory called Arrhenius theory. According to Arrhenius’s theory, a substance that gives H+ ion in its aqueous solution is called acid whereas the substance that ionizes OH– ion in the aqueous solution is called a Base.
HCl(aquaous solution) ⇌ H+ + Cl–
NaOH(aquaous solution) ⇌ Na+ + OH–
Bronsted-Lowry Theory of Acid and Base
Bronsted-Lowry Theory also provide an explanation of acid and base, according to this theory, acid is an H+ ion or a proton donor and it forms its conjugate base whereas the base is a substance that accepts an H+ ion or a proton to form conjugate acid.
According to Bronsted-Lowry acids are substances that donate a proton or H+ ion to the other compound.
Acid ⇌ Proton + Conjugate Base
Example: H2SO4 ⇌ H+ + HSO4–
According to Bronsted-Lowry bases are substances that accept a proton or H+ ion from other compounds.
Base + Proton ⇌ Conjugate Acid
Example: OH– + H+ ⇌ H2O
Strength of Acids and Bases
The strength of an acid or a base is measured by the amount of H+ ions or OH– ions present in their aqueous solution.
Strong acids have a higher concentration of H+ ions per unit volume in their aqueous solution whereas weaker acids have a lower concentration of H+ ions per unit volume in their aqueous solution. An example of a strong acid is H2SO4 and an example of a weak acid is CH3COOH.
Similarly, strong bases have a higher concentration of OH– ions per unit volume in their aqueous solution whereas weaker bases have a lower concentration of OH– ions per unit volume in their aqueous solution. An example of a strong base is KOH and an example of a weak acid is CaO.
The strength of Acids and Bases can easily be measured using a pH scale.
pH scale is used to measure the basicity and acidity of a solution. It gives the strength of any solution. pH is determined by the amount of hydrogen ion concentration in the solution.
It is calculated using the formula,
pH = -log[H+]
For an acid, pH ranges from 0 to 7 whereas for a base it ranges between 7 and 14. The lower the pH higher is the strength of the acid and the higher the pH higher the strength of the base.
Note: pH ranges of acids and bases.
- 0 < Acid < 7
- 7 < Base< 14
For more detail on pH read, Importance of pH in Everyday Life.
Indicators are chemical compounds which help to indicate the presence of acid or base in a chemical reaction. They possess different colours in acidic solutions and different colours in basic solutions. Indicators are made naturally by plants and animals or artificially by humans. The image shows a litmus test of acids and bases.
An indicator indicating the pH
- The range of 0 to 7 indicates an acidic solution.
- The range of 7 to 14 indicates the basic solution.
- 7 is a neutral solution.
Types of Indicators
There are various types of indicators used for various purposes some of which are,
- Natural Indicators: Indicators derived from plants, animals or any living organism are natural indicators. Examples, Red Cabbage, Litmus paper and others.
- Synthetic Indicators: Indicators made artificially in laboratories and factories are synthetic indicators. Examples, are Phenopthelien, Methyl orange, and others.
- Olfactory Indicators: Substances that have different smells in acidic or basic mediums are called Olfactory Indicators. Example onions, olives and others.
What are Salts?
When an acid and a base react to neutralise one another, they generate sales, which are ionic substances. Salts do not have an electrical charge. Salts come in a variety of forms, the most common of which is sodium chloride. Table salt and common salt are both terms for sodium chloride. Sodium chloride is used to make dishes taste better. The image given below shows a salt and its cation and anion.
Physical Properties of Salt
Salts have various physical properties and some of following physical properties of salts are,
- In nature, the bulk of the salts is crystalline.
- Salts that are transparent or opaque are available.
- The bulk of salts is soluble in water.
- Salt solutions, in their molten state, also transmit electricity.
- The flavour of salt can be salty, sour, sweet, bitter, or umami (savoury).
- There is no odour to neutral salts.
- Salts that are colourless or coloured are available.
- Because it contains ions, salt water is an excellent conductor of electricity.
- Electrostatic attraction holds the ions together, and a chemical bond is established between them..
Types of Salts
Salts are categorised into various categories some of the important categories are given below,
- Acidic Salt
- Basic or Alkali Salt
- Neutral Salts
A partial neutralisation of a diprotic or polyprotic acid produces an acidic salt. These salts contain H+ cations or strong cations in their aqueous solution. The ionizable H+ makes up the majority of the ions. Some examples of acidic salts are NaHSO4, KH2PO4 etc. These salts are formed by the neutralization of strong acids and weak bases.
Ammonium chloride is formed when hydrochloric acid (a strong acid) interacts with ammonium hydroxide (a weak base).
NH4OH + HCl → NH4Cl + H2O
Ammonium sulphate is formed when ammonium hydroxide (a weak base) reacts with sulphuric acid (a strong acid).
2NH4OH + H2SO4 → (NH4)2SO4 + 2H2O
Basic or Alkali Salt
A basic salt is formed when a strong base reacts with a weak acid to partially neutralise it. When they are hydrolyzed, they decompose into a basic solution. This is because when a basic salt is hydrolyzed, it produces the conjugate base of a weak acid in the solution. e.g. Sodium Carbonate (Na2CO3), Sodium Acetate (CH3COONa)
Sodium carbonate is formed when sodium hydroxide (a strong base) reacts with carbonic acid (a weak acid)
H2CO3 + 2NaOH → Na2CO3 + H2O
Sodium acetate is formed when a strongly basic, sodium hydroxide (a strong base), reacts with acetic acid (a weak acid)
CH3COOH + NaOH → CH3COONa + H2O
Salts generated by the reaction of a strong acid with a strong base are neutral in nature. The pH of these salts is 7, which is considered neutral. Potassium Chloride, Sodium Chloride, and others are examples of neutral salts.
Sodium Chloride (NaCl)
Sodium Chloride is formed when hydrochloric acid (a strong acid) mixes with sodium hydroxide (a strong base).
NaOH + HCl → NaCl + H2O
Sodium Sulphate (Na2SO4)
It’s made when sulphuric acid combines with sodium hydroxide (a strong basic) ( a strong acid).
2NaOH + H2SO4 → Na2SO4 + 2H2O
Salts can also be categorised into other categories which include,
- Mixed Salts
- Double Salt
Salts with more than one cation or anion are known as double salts. They’re created by mixing two different salts that crystallised in the same ionic lattice. e.g. Potassium Sodium Tartrate (KNaC4H4O6.4H2O) also known as Rochelle salt.
Salts which are produced by mixing two salts, which generally share a common cation or anion, are called mixed salt. e..g. Bleaching Powder CaOCl2.
What Causes the formation of Acidic, Basic and Neutral Salts?
The causes of the formation of Acidic, Basic and Neutral Salts are discussed below,
- When a strong acid reacts with a weak base, the base is unable to completely neutralise the acid. As a result, a salt that is acidic forms.
- When a strong base is combined with a weak acid, the acid is unable to completely neutralise it. As a result, you get a simple salt.
- When an equal-strength acid and base react, they totally neutralise each other. A neutral salt is formed as a result of this process.
Some Common Salts
Salts are chemical compounds which are formed as a result of a neutralization reaction between acids and bases. When we hear salt we only think about common salt which is Sodium chloride that we eat in our daily life but there are several other salts also which are widely useful. Here in this article, we will learn about some common salt which is widely used.
- Baking Soda or Sodium Bicarbonate
- Washing Soda or Sodium Carbonate
- Bleaching Powder or Calcium Hypochlorite
Baking soda also called Sodium Hydrogen Carbonate, is a chemical compound whose chemical formula is NaHCO3. Baking soda has a sodium cation (Na+) and a bicarbonate anion (HCO3–). Sodium bicarbonate is a white, crystalline powder and as the name suggests is used for baking.
Chemical Name: Sodium hydrogen carbonate
Chemical Formula: NaHCO3
Baking soda can be prepared with the help of the reaction given below.
NaCl(aq) + NH3(g) + CO2(g) + H2O(l) → NaHCO3(aq) + NH4Cl(aq)
A few of the uses of Baking Soda are,
- It is used as an antacid in case of acidity.
- It is used for baking purposes.
- It is used as a water softener.
Washing soda also called Sodium Carbonate, is a chemical compound whose chemical formula is Na2CO3. Washing soda has two sodium cations (Na+) and a carbonate anion (CO32-). Sodium carbonate is a white, crystalline powder and as the name suggests is used for washing purposes.
Chemical Name: Sodium Carbonate
Chemical Formula: Na2CO3
A few of the uses of Washing Soda are,
- It is used in the glass, soap and paper industries.
- It is used as washing powder.
Bleaching Powder also called Calcium Hypochlorite, is a chemical compound whose chemical formula is CaOCl2. Bleaching Powder is used for bleaching purposes. In its aqueous solution bleaching powder releases chlorine which is responsible for the bleaching action.
Chemical Name: Calcium Hypochlorite
Chemical Formula: CaOCl2
Bleaching Powder can be prepared with the help of the reaction given below.
Ca(OH)2(aq) + Cl2(g) → CaOCl2(aq) + H2O(l)
A few of the uses of Bleaching Powder are,
- It is used for bleaching the laundry.
- It is used as an oxidizer in many industries.
- It is used as a disinfectant to clean water
Crystals of Salts
Some salts combining with water form crystals and these water molecules which are required to form crystals are called water of crystallisation. Some examples of crystal salts are Table salt (sodium chloride crystals), Sugar (sucrose crystals).
Plaster of Paris
Plaster of Paris is a widely used chemical compound is used for various purposes such as sculpting materials, gauze bandages, building and furnishing houses and others. Plaster of Paris is hydrated calcium sulphate obtained by calcining gypsum. It is a white powdery chemical compound.
Chemical Name: Calcium Sulphate Hemi Hydrate.
Chemical Formula: CaSO4. ½ H2O
Preparation of Plaster of Paris
Plaster of Paris can easily be prepared with the help of the equation given below,
CaSO4.2H2O (s) (heating at 100°C ) —> CaSO4. ½ H2O + 3/2 H2O
FAQs on Acids, Bases and Salts
Question 1: What are salts in acids, bases and, salts?
The neutralization reaction of acids and bases results in a substance called salt. Salts are made of cations and anions. Some examples of salt are NaCl, Na2SO4
Question 2: What are the two types of acids?
Acids can easily be categorised as,
- Inorganic Acids: Examples, Sulphuric Acid (H2SO4), Nitric acid (HNO3), and others.
- Organic Acids: Examples, Acetic acid Citric acid, and others.
Question 3: What is the difference between an acid and a base?
Acids and bases are two types of corrosive chemicals. Acids are ionic chemicals that break down in water to create the hydrogen ion (H+) and they have a pH value between 0 and 7, while base are ionic chemicals that break down in water to create the hydronium ion (OH–) and they have a pH value between 7 and 14.
Question 3: What are the physical properties of bases?
The physical properties of bases are,
- They have a bitter taste to them.
- Their aqueous solutions have a soapy quality to them.
- They change the colour of litmus paper from red to blue.
- Their aqueous solutions are electrically conductive.
- In an aqueous solution, they release OH– ions.
Question 4: What are the physical properties of acids?
The physcial properties of the acids are,
- Acids have a sour flavour to them.
- Blue litmus turns red.
- Electricity can be conducted through an acidic solution.
- In an aqueous solution, they release H+ ions.
Question 5: What happens when hydrochloric acid reacts with sodium carbonate?
When hydrochloric acid combines with sodium carbonate, it produces carbon dioxide gas, sodium chloride, and water.
Na2CO3 + 2HCl → 2NaCl + H2O + CO2
Question 6: Are salt basic or acidic?
A salt can either be basic ar be acidic depending on the types of acid and base that react to form a salt.
Question 7: Is NH4Cl a basic salt?
No, Ammonium chloride (NH4Cl) is an acidic salt because it is a salt of a strong acid (hydrochloric acid) and a weak base (ammonium hydroxide).
Question 8: What happens when metal reacts with HCl?
Metal reacting with acid produces salt and hydrogen.
Acid + Metal → Salt + Hydrogen
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