Acids and Bases: Properties, Uses & Examples

Acids and bases are chemical compounds that were given by Savante Arrhenius in the year 1884. These compounds interact with each other, which results in the formation of salt and water. 

• Acids and bases are naturally occurring compounds that can also be created artificially. 
• The word acid is derived from the Latin word acere, which means sour.
• Base is a chemical compound that has OH ions dissolved in it.

Acids and bases are chemically opposite compounds as the effect of an acid includes an increase in the concentration of hydronium ions in water, whereas bases reduce this concentration of ions. 

• We use many of these compounds in our everyday lives.
• Soaps are a common example of bases, and vinegar is a common example of acids.

Key Terms: Acids and bases, Acids, Bases, pH, Salt, Water, Arrhenius Theory, Bronsted-Lowry Theory, Lewis Acid-base Theory, Ions, Carbonates, Metal Oxides, Aqueous Solution, Substance, Carbon Dioxide

Acids and Bases Definitions

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Acids and bases can be defined in various ways depending upon the properties of acidity and basicity. According to Arrhenius, acids are chemical compounds that ionize hydrogen and bases are compounds that ionize hydroxide ions.

Acids

An acid is a hydrogen-containing substance that is usually identified by its sour taste. It is a substance which releases one or more H⁺ ions in an aqueous solution. 

• It is used to turn blue litmus paper red.
• As per Lowry-Bronsted, acids are proton donors.
• They are capable of coordinating with unshared electron pairs.
• Many acids are present in our food items. 
• Citric acid is present in lemons, oranges, etc.
• The lactic acid in milk and curd. 
• Ants and bees have formic acid in their stings.

Bases

Bases are chemical compounds that do not taste sour but are bitter in taste and feel soapy. In an aqueous solution, the base is the chemical that releases one or more hydroxyl ions.

• According to the Lowry-Bronsted, a base is a proton acceptor.
• It is used to turn red litmus paper blue.
• They consist of unshared electron pairs available for sharing with acids. 

On examination of the chemical formula of these substances, we find they contain one or more hydroxyl groups, which are released when the substance is dissolved in water. 

• A few bases, such as calcium hydroxide, are present in lime water.
• Magnesium hydroxide which is present in the milk of magnesia.

Acids and Bases

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Theories of Acids and Bases

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There are three main theories that define, acid and bases which include Arrhenius Theory, Bronsted-Lowry Theory and Lewis Acid-base theory.

Arrhenius Theory

According to the Arrhenius theory of acid-base, acids are a substance that dissolves in an aqueous solution to give hydrogen ions. It describes bases as substance which dissolves in an aqueous solution to give hydroxide ions.

Bronsted-Lowry Theory 

Bronsted-Lowry Theory is also known as the proton theory of acid and base. According to theory, acid is a substance that donates a proton or hydrogen ion to another compound and forms a conjugate base. 

• On the other hand, bases are substances that accept protons or hydrogen ions from other compounds. 
• This theory of acid-base reaction involves the transfer of proton or hydrogen ions.

Lewis-Acid Base 

According to this theory, a substance accepts a pair of electrons to form a covalent bond, while a Lewis base is a substance that donates a pair of electrons to form a covalent bond.

pH of Acids and Bases

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pH of a substance is defined as a measurement of the basicity or acidity present in a solution. It ranges from 0 to 14, where 0 indicates the acidic solution, and 14 indicates the basic solution.

• The range of 0 to 6 indicates an acidic solution.
• Seven is used to indicate a neutral solution.
• The range of 8 to 14 indicates a basic solution.
• Another way to check for acids and bases solutions is through the use of litmus paper.
• There are two types of litmus paper used, namely red litmus paper and blue litmus paper.
• Red litmus paper will turn the basic solution blue.
• Blue litmus paper will turn the acidic solution red.

Physical Properties of Acids and Bases

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The physical properties of acids and bases are as follows:

Physical Properties of Acids

The physical properties of Acids are as follows:

• Acid solutions are sour in taste.
• They are used to turn blue litmus paper red.
• These solutions have high boiling points.
• Acids are considered good conductors of electricity.

Physical Properties of Bases

The physical properties of Bases are as follows:

• Basic solutions are bitter in taste.
• They are used to turn red litmus paper blue.
• The base is used for the conduction of electricity.

Chemical Properties of Acids and Bases

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The chemical properties of acids and bases are as follows:

Chemical Properties of Acids

The acids are characterized by the presence of one or more hydrogen atoms in their molecule. This hydrogen ion is dissolved in water to release this hydrogen ion. 

• The chemical properties of acids are described below:

Actions with Metals

Acids react with metals to form metals, salt, and hydrogen.

Metal + Dilute Acid ---→ Metal Salt + Hydrogen

Action with Metal Oxides

On heating, acids react with metal oxides to generate salt and water.

Metal Oxide + Acid ---→ Salt + Water

Action with Metal Carbonates and Metal Hydrogen Carbonates

Acids react with metal carbonates and metal hydrogen carbonates to evolve carbon dioxide and form salts.

Metal Carbonates + Acid ----> Salt + Carbon Dioxide

Metal hydrogen carbonates + Acid ----> Salt + Carbon Dioxide

Strong Acids and Weak Acids

The acids that completely ionize in the water are called strong acids, while acids that ionize to some extent in the water are called weak acids. A few examples of strong acids are HCl, H₂SO₄, HNO₃, etc.

Chemical Properties of bases

As we know, the chemical properties of acids are due to the participation of hydrogen ions in the reaction; similarly, bases also react due to the presence of hydroxyl ions in the group.

Action with Metals

Metals react with a strong base, such as NaOH, KOH, etc., to evolve hydrogen gas.

Base + Metal -------> Hydrogen + Metal Salt

Action with Non-Metallic Oxide

Bases react with oxides of non-metal and form salt and water.

Base + Metal Oxide ------> Salt + Hydrogen

Strong and Weak Base

Bases that are completely ionizable in the water are called strong bases, and bases that ionize to some extent only are called weak bases. Methylamine and glycine are weak bases, while potassium hydroxide and sodium hydroxide are strong bases.

Uses of Acids and Bases

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Various uses of acids and bases are as follows:

Uses of Acid

The uses of acids are as follows:

• Acids are used in the pickling process, where they act as preservatives.
• Few fruits contain citric acid which are also used in the preservation of food.
• Sulfuric acid is used in wet cell batteries and car batteries.
• Many soft drinks contain phosphoric acid.

Uses of Bases

The uses of bases are as follows:

• Bases are involved in the manufacture of soaps.
• Compounds such as slaked lime are used in the manufacture of bleaching powder.
• Magnesium hydroxide, also known as milk of magnesia, is used as a laxative.
• Bases such as ammonium hydroxide are used as important reagents in the laboratory.

Things to Remember

• Acids and bases are popular chemicals consisting of hydrogen and hydroxide ions.
• The concept can be explained with the help of Bronsted-Lowry's theory and Arrhenius's theory.
• The acidity and basicity of the solution can be checked by the use of litmus paper.
• Acids are divided on the basis of occurrence and concentration.
• Bases are divided on the basis of acidity and degree of ionization.
• Hydrochloric acid, sulphuric acid, and nitric acids are a few examples of strong acids.
• Acetic acid, formic acid, and oxalic acids are a few examples of weak acids.
• Sodium hydroxide, barium hydroxide, and potassium hydroxide are a few examples of strong bases.

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