Chemical Properties of Acids and Bases: Meaning, Reaction and Examples

Chemical Properties of Acids and Bases: Acids and bases play an important role in our daily lives. Many of the foods we consume are acidic in nature. Lemons and oranges contain citric acid, and vinegar is an acetic acid solution. Baking soda is a common household item and it’s a base. Bases have a harsh taste to them, and their solutions are slick and soapy. Their chemical properties are varied and interesting. This article will go in-depth into the ‘Chemical Properties of Acids and Bases’.

Acids are a distinct class of compounds because of the properties of their aqueous solutions. The properties of bases are mostly in opposition to those of acids. Before we look at the chemical properties of acids and bases, we’ll look at what acids and bases signify. This article will also discuss commonly searched queries like ‘properties of acids and bases’, ‘properties of acids class 10’, ‘physical properties of acids and bases’, and ‘chemical properties of acids class 10’ which will help in studying the properties of acid and base

Acids

The word ‘acid’ is derived from the Latin word acidus, which means sour. All acids are sour to taste. Acids that are present in fruits and naturally occurring substances are called organic acids. They are found in animal and plant products. Vitamin C or ascorbic acid is also called an organic acid. The acids that are obtained from minerals are called inorganic acids or mineral acids. Some examples of organic acids are as follows:

Some examples of inorganic acids are as follows:

Acids may also be defined according to the Arrhenius concept as chemical compounds that, when dissolved in water, yield hydronium ions \(\left[ {{{\rm{H}}_3}{{\rm{O}}^ + }} \right]\) as the only positively charged ions.

Physical Properties of Acids

1. Taste: Acids have a sour taste.
2. Physical state: Some acids are solids, while others are liquids at room temperature.
   For example, oxalic acid, boric acid, etc., are solids, while acetic acid, formic acid, etc., are liquids.
3. Corrosive nature: Most of the acids are corrosive in nature. They produce a burning sensation on the skin and holes in the clothes on which they fall.
4. Action of indicators: They turn blue litmus red, they change the colour of methyl orange from orange to red, Phenolphthalein remains colourless in acidic solutions.

Chemical Properties of Acids

1. Reaction With Active Metals

Dilute acids like \({\rm{HCl}}\) and \({{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4}\) react with active metals like zinc, magnesium, iron, etc., to evolve hydrogen gas.

\({\rm{Metal}} + {\rm{Dilute}}\,{\rm{acid}} \to {\rm{Metal}}\,{\rm{salt}} + {\rm{Hydrogen}}\)

For example,

(i) Zinc metal reacts with dilute sulphuric acid to liberate hydrogen gas along with the formation of zinc sulphate.

\({\rm{Zn}} + {{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4} \to {\rm{ZnS}}{{\rm{O}}_4} + {{\rm{H}}_2} \uparrow \)

(ii) Magnesium metal reacts with dilute hydrochloric acid to liberate hydrogen gas along with the formation of magnesium chloride.

\({\rm{Mg}} + {\rm{HCl}} \to {\rm{MgC}}{{\rm{l}}_2} + {{\rm{H}}_2} \uparrow \)

(iii) Metal iron reacts with dilute sulphuric acid to liberate hydrogen gas along with the formation of ferrous sulphate.

\({\rm{Fe}} + {{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4} \to {\rm{FeS}}{{\rm{O}}_4} + {{\rm{H}}_2} \uparrow \)

Some metals like copper and silver are less reactive, and they do not react with dilute acids.

Thus, all metals do not react with the same acid with the same vigour. Highly active metals placed above hydrogen in the activity series react vigorously with dilute acids to liberate hydrogen gas, whereas less active metals react less vigorously with dilute acids.

2. Reaction of Metal Carbonates/Bicarbonates With Acid

Dilute acids react with metal carbonates and bicarbonates to liberate carbon dioxide gas with brisk effervescence and form corresponding salt and water.

\({\rm{Metal}}\,{\rm{carbonates}}/{\rm{bicarbonates}} + {\rm{Acid}} \to {\rm{Salt}} + {\rm{water}} + {\rm{carbon}}\,{\rm{dioxide}}\)

For example,

(i.) Sodium carbonate reacts with dilute sulphuric acid to liberate carbon dioxide along with the formation of sodium sulphate and water.

\({\rm{N}}{{\rm{a}}_2}{\rm{C}}{{\rm{O}}_3} + {{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4} \to {\rm{N}}{{\rm{a}}_2}{\rm{S}}{{\rm{O}}_4} + {{\rm{H}}_2}{\rm{O}} + {\rm{C}}{{\rm{O}}_2} \uparrow \)

(ii) Sodium hydrogen carbonate reacts with dilute hydrochloric acid to liberate carbon dioxide along with the formation of sodium chloride and water.

\({\rm{NaHC}}{{\rm{O}}_3} + {\rm{HCl}} \to {\rm{NaCl}} + {{\rm{H}}_2}{\rm{O}} + {\rm{C}}{{\rm{O}}_2} \uparrow \)

(iii) Limestone, chalk and marble, which are different forms of calcium carbonate, react with dilute hydrochloric acid to liberate carbon dioxide and the formation of calcium chloride and water.

\({\rm{CaC}}{{\rm{O}}_3} + 2{\rm{HCl}} \to {\rm{CaC}}{{\rm{l}}_2} + {{\rm{H}}_2}{\rm{O}} + {\rm{C}}{{\rm{O}}_2} \uparrow \)

If someone is suffering from the problem of acidity due to overeating, they are advised to take a pinch of baking soda. This is because baking soda is sodium bicarbonate, which is a base that neutralises the excess of hydrochloric acid in the stomach and thus, the person gets relief from burning caused due to acidity.

3. The Reaction of Acids With Bases

When an acid reacts with a base, it forms salt and water. This reaction is called neutralisation.

\({\rm{Acid}} + {\rm{Base}} \to {\rm{Salt}} + {\rm{Water}}\)

For example, when hydrochloric acid reacts with sodium hydroxide solutions, then a neutralisation reaction takes place to form sodium chloride and water.

\({\rm{NaOH}} + {\rm{HCl}} \to {\rm{NaCl}} + {{\rm{H}}_2}{\rm{O}}\)

4. Reaction of Metallic Oxides With Acids

Acids react with metal oxides to form salt and water. Thus, the reaction between metallic oxides and acids is a kind of neutralisation reaction.

\({\rm{Metal}}\,{\rm{Oxide}} + {\rm{Acid}} \to {\rm{Salt}} + {\rm{Water}}\)

For example, when a black metallic oxide that is copper oxide reacts with hydrochloric acid forms a blue-green copper chloride and water.

\({\rm{CuO}} + 2{\rm{HCl}} \to {\rm{CuC}}{{\rm{l}}_2} + {{\rm{H}}_2}{\rm{O}}\)

Bases

Bases taste bitter and feel slippery or soapy to touch. A base is either a metallic hydroxide or metallic oxide or aqueous ammonia, which reacts with an acid to form salt and water only.

According to the Arrhenius concept, a base is a substance which when dissolved in water, gives hydroxyl ions \(\left( {{\rm{O}}{{\rm{H}}^ – }} \right)\) as the only negative ion in the solution.

Alkali

An alkali is a base soluble in water. An alkali is a compound which when dissolved in water, yields hydroxyl ions \(\left( {{\rm{O}}{{\rm{H}}^ – }} \right)\) as the only negatively charged ions. Bases that are not soluble in water are not alkalies. Thus, all alkalies are bases, but not all bases are alkalies.

Examples of some common alkalies are as follows:

Physical Properties of Base

1. Taste and feel: Bases have a bitter taste, and their solution feels slippery or soapy.
2. Corrosive nature: Strong bases have strong burning action on the skin and may produce blisters.
3. Action of indicators: They turn red litmus solution blue, change methyl orange from orange to yellow, and change colourless phenolphthalein to pink.
4. Conduction of electricity: Like acids, the solutions of bases in water also conduct electricity.

Chemical Properties of Base

Reaction With Acids

Bases react with acids to form only salt and water. This reaction is called neutralisation.

For example, sodium hydroxide reacts with hydrochloric acid to form sodium chloride and water only.

\({\rm{NaOH}} + {\rm{HCl}} \to {\rm{NaCl}} + {{\rm{H}}_2}{\rm{O}}\)

Alkalies Precipitate Insoluble Metal Hydroxides

Solution of alkalies precipitates insoluble hydroxides of metals from the solution of their salts.

For example,

a. Copper chloride reacts with sodium hydroxide and gives a bluish-white precipitate of copper hydroxide along with the formation of sodium chloride.

\({\rm{CuC}}{{\rm{l}}_2}({\rm{aq}}) + 2{\rm{NaOH}}({\rm{aq}}) \to {\rm{Cu}}{({\rm{OH}})_2}(\;{\rm{s}}) \downarrow + 2{\rm{NaCl}}({\rm{aq}})\)

b. Iron chloride reacts with ammonium hydroxide to form a reddish-brown precipitate of iron hydroxide along with the formation of ammonium chloride.

\({\rm{FeC}}{{\rm{l}}_3}({\rm{aq}}) + 3{\rm{N}}{{\rm{H}}_4}{\rm{OH}}({\rm{aq}}) \to {\rm{Fe}}{({\rm{OH}})_3}(\;{\rm{s}}) \downarrow + 3{\rm{N}}{{\rm{H}}_4}{\rm{Cl}}({\rm{aq}})\)

Alkalies Liberate Ammonia From Ammonium Salts

Alkalies on heating with ammonium salts liberate ammonia gas.

For example, Whenever ammonium chloride is heated along with sodium hydroxide, it liberates ammonia gas along with the formation of sodium chloride and water.

\({\rm{N}}{{\rm{H}}_4}{\rm{Cl}}({\rm{s}}) + {\rm{NaOH}}({\rm{aq}})\mathop \to \limits^\Delta {\rm{NaCl}}({\rm{aq}}) + {{\rm{H}}_2}{\rm{O}}({\rm{l}}) + {\rm{N}}{{\rm{H}}_3}(\;{\rm{g}}) \uparrow \)

Reaction of Alkalies With Metals

Some bases like sodium hydroxide and potassium hydroxide react with active metals like zinc and aluminium to liberate hydrogen gas.

For example,

a. Reaction of zinc with sodium hydroxide gives sodium zincate and liberates hydrogen gas.

\({\rm{Zn}} + 2{\rm{NaOH}} \to {\rm{N}}{{\rm{a}}_2}{\rm{Zn}}{{\rm{O}}_2} + {{\rm{H}}_2}\)

b. Whenever aluminium reacts with sodium hydroxide, it gives sodium aluminate along with the liberation of hydrogen gas.

\(2{\rm{Al}} + 2{\rm{NaOH}} + 2{{\rm{H}}_2}{\rm{O}} \to 2{\rm{NaAl}}{{\rm{O}}_2} + 3{{\rm{H}}_2}\)

Reaction of Bases With Non-Metallic Oxides

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

For example,

a. Sodium hydroxide reacts with carbon dioxide to form sodium carbonate and water.

\(2{\rm{NaOH}}({\rm{aq}}) + {\rm{C}}{{\rm{O}}_2}(\;{\rm{g}}) \to {\rm{N}}{{\rm{a}}_2}{\rm{C}}{{\rm{O}}_3}({\rm{aq}}) + {{\rm{H}}_2}{\rm{O}}({\rm{l}})\)

b. Calcium hydroxide reacts with sulphur dioxide to form calcium sulfite and water.

\({\rm{Ca}}{({\rm{OH}})_2}(\;{\rm{s}}) + {\rm{S}}{{\rm{O}}_2}(\;{\rm{g}}) \to {\rm{CaS}}{{\rm{O}}_3}({\rm{aq}}) + {{\rm{H}}_2}{\rm{O}}({\rm{l}})\)

Summary

In this article, we studied the physical and chemical characteristics of acids and bases. We also studied how different indicators change their colour on coming in contact with acids and bases. Also, now we know the different reactions like – reaction of acids with base, reactions of acids with metals, the reaction of alkalies with metal hydroxides, etc.

FAQs on Properties of Acids and Bases

We have provided some frequently asked questions on the Chemical Properties of Acids and Bases here:

Q.1. What is a neutralisation reaction?
Ans: When an acid reacts with a base, it forms salt and water. This reaction is called neutralisation.
\({\rm{Acid}} + {\rm{Base}} \to {\rm{Salt}} + {\rm{Water}}\)
For example, when hydrochloric acid reacts with sodium hydroxide solutions, then a neutralisation reaction takes place to form sodium chloride and water.
\({\rm{NaOH}} + {\rm{HCl}} \to {\rm{NaCl}} + {{\rm{H}}_2}{\rm{O}}\)

Q.2. Why is it advised to have a pinch of baking soda when suffering from acidity?
Ans: If someone is suffering from the problem of acidity due to overeating, they are advised to take a pinch of baking soda. This is because baking soda is sodium bicarbonate, which is a base that neutralises the excess of hydrochloric acid in the stomach and thus, the person gets relief from burning caused due to acidity.

Q3. Compare the physical properties of acids and bases?
Ans: The difference between the physical properties of acids and bases are as follows:

Q.4. What are the chemical properties of acids?
Ans: The chemical properties of acids are as follows:
1. They react with active metals to liberate hydrogen gas.
2. They react with bases to form salt and water.
3. They react with metal carbonates/ metal bicarbonates to liberate carbon dioxide gas.
4. They react with metal oxides to form salt and water only.

Q.5. What are the chemical properties of bases?
Ans: The chemical properties of bases are as follows:
1. They react with acids to form salt and water.
2. They react with non-metallic oxides to form salt and water only.
3. Some bases react with metals to liberate hydrogen gas.
4. Alkalis liberate ammonia from ammonium salts.
5. Alkalis precipitate insoluble metal hydroxides.