Hydrogen is an important chapter in NCERT Class 11 Chemistry book. It is the lightest element in the periodic table which exists in nature as a hydrogen molecule. It has the simplest atomic structure and is easier for students to understand the same. 70% of the total mass of the universe is due to Hydrogen and it is also the most abundant element. In this article, we will learn more about this exciting element.

What Is Hydrogen?

Hydrogen element is a chemical with symbol H and atomic number \(1\) and has an average atomic mass of \(1.008{\rm{ }}amu.\) This gas was first produced in an experiment by Robert Boyle in the year \(1672.\) Its properties were studied in the year \(1766\) by an English scientist named Henry Cavendish, and in the year \(1772,\) this gas was discovered by Daniel Rutherford. In \(1783,\) Lavoisier named this gas Hydrogen. The name is derived from the Greek words ‘hydro’ and ‘genes’ meaning water producer.

Hydrogen is a colourless, odourless, and highly flammable gas. It is the lightest element of the periodic table and one of the most abundant elements found in the universe. It occurs as a diatomic molecule in nature as \({{\rm{H}}_2}\) Its molecule has a single covalent bond between both hydrogen atoms. The electronic configuration according to electron distribution is \(1\), which means that there is one electron present in the K-shell, and thus, it has \(1\) valence electron, and it shows a valency of \(1\). Also, its electronic configuration according to shell distribution- \(1{{\rm{s}}^1}\)

Occurrence of Hydrogen

In the state, Hydrogen is found in the Sun and most of the stars, and the planet Jupiter is composed mostly of Hydrogen. On Earth, Hydrogen occurs in very small quantities in volcanic gases.

In a combined state

1. Hydrogen occurs in vast quantities as part of the water in oceans, ice packs, rivers, lakes, and the atmosphere.
2. As part of innumerable carbon compounds, Hydrogen is present in all animals and vegetable matter.
3. Acids, alkalis, petroleum, natural gas, etc., are all compounds containing Hydrogen.

Atomic Structure of Hydrogen

The atomic number of Hydrogen is 1, which indicates that there is only one electron that revolves around the nucleus of the atom, and it has only one proton and no neutron present inside the nucleus of the atom.

Preparation of Hydrogen

The principal sources of Hydrogen on Earth are water, acids, and alkalis. These compounds liberate Hydrogen gas when they react chemically.

1. By Electrolysis of Water

By this method, Hydrogen is prepared on a large scale. When an electric current is passed through acidulated water, it decomposes into hydrogen and oxygen.

Hydrogen is collected at the cathode, and oxygen is collected at the anode. The ratio of Hydrogen and oxygen collected is \(2:1\) by moles. The setup for electrolysis of water is shown below:

2. By Active Metals

When dilute hydrochloric acid or dilute sulphuric acid reacts with metals placed above Hydrogen in the activity series, Hydrogen gas is liberated.

Active metals like magnesium, zinc, iron, etc., react with dilute hydrochloric acid or dilute sulphuric acid to liberate hydrogen gas.

Reaction of metals with dilute \({\rm{HCl}}\)	Reaction of metals with dilute \({{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4}\)
\({\rm{Mg}}\,{\rm{ + }}\,{\rm{2HCl}}\,\, \to \,{\rm{MgC}}{{\rm{l}}_2}\, + \,{{\rm{H}}_2}\) \({\rm{Zn}}\,\, + \,\,2{\rm{HCl}}\, \to \,{\rm{ZnC}}{{\rm{l}}_2}\, + \,{{\rm{H}}_2}\) \({\rm{Fe}}\,\, + \,\,2{\rm{HCl}}\, \to \,{\rm{FeC}}{{\rm{l}}_2}\, + \,{{\rm{H}}_2}\)	\({\rm{Mg}}\,{\rm{ + }}\,{{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4} \to \,{\rm{MgS}}{{\rm{O}}_4}\) \(Zn\,\, + \,{{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4}\, \to \,{\rm{ZnS}}{{\rm{O}}_4}\)

3. Laboratory Preparation

In the laboratory, Hydrogen is prepared by the action of dilute hydrochloric acid or dilute sulphuric acid with zinc granules.

Reaction: –

\({\rm{Zn}}\, + \,{\rm{HCl}} \to {\rm{ZnC}}{{\rm{l}}_{2}}\, + \,{{\rm{H}}_2}\,({\rm{g}})\)

\({\rm{Zn}}\,\, + \,{{\rm{H}}_2}{\rm{S}}{{\rm{O}}_4}\, \to \,{\rm{ZnS}}{{\rm{O}}_4} + {{\rm{H}}_{2\,}}({\rm{g}})\)

Why is granulated zinc preferred in the above reaction?

Granulated zinc contains an impurity, copper, which acts as a positive catalyst for the reaction in the laboratory preparation of Hydrogen.

Procedure

Put some pieces of zinc granules in a round bottom flask fitted with two airtight cork with two holes. Through one hole, with the help of a thistle funnel, add dilute hydrochloric acid or dilute sulphuric acid to the zinc granules. A brisk effervescence indicates the liberation of Hydrogen gas.

The laboratory setup for preparation of Hydrogen:

The laboratory setup for preparation of Hydrogen:

Collection of gas
Hydrogen gas will be collected with the help of a delivery tube through the downward displacement of water because Hydrogen gas is lighter than water.

4. Industrial Process

Industrially, Hydrogen is prepared through Bosch’s process. It is done by passing steam over red-hot coke at a high temperature of about \({1000^ \circ }C.\) The products are carbon monoxide and Hydrogen, and this mixture is called water gas.

\({\rm{C}}\,\, + \,\,{{\rm{H}}_2}{\rm{O}}\,\, \to \,{\rm{CO}}\, + \,{{\rm{H}}_2}\)

This reaction is endothermic in nature. It is difficult to separate Hydrogen from water gas. Therefore, water gas is mixed with excess steam and passed over a catalyst ferric oxide or chromium oxide. This reaction is carried out at 450℃.

The reaction is exothermic in nature. The carbon dioxide produced can be separated from the water gas mixture by dissolving the mixture at 30 atmospheric pressure. Carbon dioxide leaves Hydrogen gas behind and dissolves in water to form carbonic acid.

Test for Hydrogen

1. Hydrogen ignites in the air. If Hydrogen is present in a test tube, a lighted splint held near its mouth ignites with a squeaky pop.
2. Hydrogen is combustible, but it does not support combustion.

Properties of Hydrogen

We get you some of the properties of Hydrogen below:

Physical Properties

1. Hydrogen is a colourless, odourless, and tasteless gas.
2. It is the lightest gas known. It is lighter than air.
3. It is highly flammable.
4. At standard temperature and pressure, Hydrogen is nontoxic.
5. It has two distinct oxidation states, \(\left( { + 1, – 1} \right).\)
6. It is very slightly soluble in nature.
7. It is collected by downward displacement of water.
8. It is a combustible gas but does not support combustion.

Chemical Properties

Hydrogen is a reactive element, it reacts with non-metals, metals, metallic oxides, and even organic compounds under appropriate conditions.

1. Reaction with non-metals: Non-metals react with Hydrogen to form their respective hydrides. For example:

\({{\rm{H}}_2}\, + \,{\rm{C}}{{\rm{l}}_2}\, \to \,2{\rm{HCl}}\)

\({{\rm{H}}_{2\,}}\, + \,{\rm{S}}\, \to \,{{\rm{H}}_2}{\rm{S}}\)

\({\rm{3}}{{\rm{H}}_2} + \,{\rm{N}}{\,_2} \to 2{\rm{N}}{{\rm{H}}_3}\)

2. Reaction with metals: Certain metals react with Hydrogen to form their respective hydrides. For example:

\(2{\rm{Na}}\,{\rm{ + }}\,{{\rm{H}}_2}\, \to 2{\rm{NaH}}\)

\({\rm{2k}}\,{\rm{ + }}\,{{\rm{H}}_2}\, \to 2{\rm{KH}}\)

\({\rm{Ca}}\,{\rm{ + }}\,{{\rm{H}}_{2\,}} \to {\rm{Ca}}{{\rm{H}}_2}\)

3. Reaction with metallic oxide: Hydrogen acts as a good reducing agent. When Hydrogen gas is passed over hot metallic oxides, it reduces the oxides of less reactive metals to metals.

\({\rm{CuO}}\,\, + \,{{\rm{H}}_2}\, \to \,{\rm{Cu}}\,\, + \,{{\rm{H}}_2}{\rm{O}}\)

\({\rm{PbO}}\,{\rm{ + }}\,{{\rm{H}}_{2\,}} \to \,{\rm{Pb}}\,\, + \,{{\rm{H}}_2}{\rm{O}}\)

4. Hydrogen gas is neutral to litmus. It shows no change in the moist red or blue litmus paper when it is dipped or introduced in a jar containing Hydrogen.

Similarities of Hydrogen with alkali metals and Halogens:

Hydrogen shows dual nature, that is, it behaves like an alkali metal as well as like a halogen because it only has a single electron in its outer shell.
This happens because Hydrogen atoms can easily gain an electron to create a full outer shell configuration just like a halogen or lose an electron like an alkali metal. Thus, it shows similarities with alkali metals and halogens.

Dissimilarities of Hydrogen with alkali metals and halogens:

1. Hydrogen has only one shell, whereas alkali metals and halogens have more than one shell.
2. Oxides of Hydrogen are neutral in nature, whereas oxides of alkali metals are basic in nature and that of halogens are acidic in nature.

Density of Hydrogen

Hydrogen gas is very light and less dense than air. The density of Hydrogen gas at STP is \({\rm{0}}{\rm{.08988}}\,{\rm{g}}/{\rm{L}}\)
.

Isotopes of Hydrogen

Isotopes are two or more types of atoms that have the same atomic number and position in the periodic table but differ in mass numbers due to the different numbers of neutrons in their nuclei. There are three isotopes of Hydrogen, and Hydrogen is the only element whose isotopes has different names. The isotopes are protium \({{\rm{(}}^1}{\rm{H)}}\) deuterium \({{\rm{(}}^2}{\rm{H)}}\) and tritium \({{\rm{(}}^2}{\rm{H)}}\)

Uses of Hydrogen

1. As a fuel: Liquid Hydrogen is used as rocket fuel. It is a pollution-fuel because it gives water upon combustion.
2. For hydrogenation of vegetable oil: Hydrogen is used in the preparation of solid vanaspati ghee from liquid vegetable fats like groundnut oil, coconut oil, etc. This process is called catalytic hydrogenation of oils.
3. For the manufacture of chemicals: Hydrogen is used in the manufacture of hydrochloric acid, methanol, urea, etc.
4. Hydrogen is also used in the production of ammonia gas, used in the manufacture of nitric acid and fertilizers.
5. As a reducing agent: It is used to reduce the lesser reactive metals like copper, tin, lead, etc., from their respective oxides.
6. It powers the Sun and many stars through the fusion of Hydrogen into Helium.
7. As an oxy-hydrogen torch: The Hydrogen and oxygen are burnt in a specially designed apparatus, and its flame is used for cutting and welding metals.

Summary

From this article, we can conclude that Hydrogen is the most abundant chemical substance in the universe and occurs in a as well as a combined state. Its dual nature makes it more important and it has various uses in our day to day life, in agricultural, industrial and commercial fields.

FAQs on Hydrogen

Below are the frequently asked questions on Hydrogen:

1. What are the uses of Hydrogen?
Ans: Some of the uses of Hydrogen are as follows:
a. As a fuel: Liquid Hydrogen is used as rocket fuel. It is a pollution-fuel because it gives water upon combustion.
b. For hydrogenation of vegetable oil: Hydrogen is used in the preparation of solid vanaspati ghee from liquid vegetable fats like groundnut oil, coconut oil, etc. This process is called catalytic hydrogenation of oils.
c. For the manufacture of chemicals: Hydrogen is used in the manufacture of hydrochloric acid, methanol, urea, etc.
d. As a reducing agent: It is used to reduce the lesser reactive metals like copper, tin, lead, etc., from their respective oxides.

2. Is Hydrogen metal or non-metal?
Ans: It behaves both like an alkali metal and a halogen due to its electronic configuration that is ns¹. It can donate one electron and can also accept one electron to complete its shell.

3. Why has helium replaced Hydrogen gas for meteorological purposes?
Ans: Hydrogen gas is inflammable in nature. Often, the balloons containing Hydrogen catch fire, so non-explosive helium gas is used instead.

4. What exactly is Hydrogen?

Ans:Hydrogen is a colourless, odourless, non- toxic, highly combustible, highly flammable and a diatomic gas with the formula ({{rm{H}}_2}) It is the lightest element of the periodic table and one of the most abundant elements found in the universe. Its molecule has a single covalent bond between both Hydrogen atoms. The electronic configuration according to electron distribution is (1), which means that there is one electron present in the K-shell. Thus, it has (1) valence electron, and it shows a valency of (1). Also, its electronic configuration according to shell distribution- (1{{rm{s}}^1})

5. Why is Hydrogen not placed in the halogen group?
Ans: Hydrogen is placed above group IA in the periodic table because it has ns¹ electron configuration like the alkali metals.

6. Which metal can absorb Hydrogen?
Ans: At room temperature and atmospheric pressure (STP), palladium can absorb up to 900 times its own volume of Hydrogen.

7. Is Hydrogen gas ({{rm{H}}_2})or({rm{H}})?

Ans:The symbol of Hydrogen is H, and it occurs as a diatomic molecule. Therefore, it is written as ({{rm{H}}_2}) The single atom of Hydrogen that is ({rm{H}}), is highly unstable as it contains only (1) electron, in order to achieve the inert gas configuration, it shares its single electron with that of other Hydrogen atom and becomes diatomic.

8. Can Hydrogen kill you?
Ans: No, pure Hydrogen cannot kill us, but lack of oxygen can. Breathing pure Hydrogen makes the voice higher-pitched, but a few lungfuls of it will deprive the lungs of oxygen.

9. Where can you find Hydrogen?
Ans: Hydrogen is one of the abundant elements that is found on Earth. Hydrogen is also found in the sun and most of the stars. On Earth, Hydrogen occurs in vast quantities as part of the water, and, as part of innumerable carbon compounds, Hydrogen is present in all animals and vegetable matter, acids, alkalis, petroleum, natural gas, etc.

10. What are \(3\) interesting facts about Hydrogen?
The three interesting facts about Hydrogen are as follows-
1. Hydrogen is the only element that can exist without neutrons.
2. About \(10\) percent of the weight of living organisms is Hydrogen – mainly in water, proteins and fats.
3. Liquid Hydrogen has the lowest density of any liquid.

11. How will you test for Hydrogen gas?
Ans: Hydrogen gas can be tested by bringing a burning candle near the gas, if it burns with a pop sound, it will confirm that the gas liberated is Hydrogen.

12. Why is nitric acid not used in the manufacturing of Hydrogen?
Ans: Nitric acid is a strong oxidizing agent even in its diluted form. When it is used to prepare Hydrogen, it will oxidize the liberated Hydrogen gas and will convert it into water. Thus, it is not used in the preparation of Hydrogen.

13. Why is the hydrogenation of vegetable oils known as catalytic hydrogenation?
Ans: Hydrogenation of vegetable oils is known as catalytic hydrogenation because it takes place in the presence of finely divided nickel, or palladium, or platinum acting as a catalyst.

Study About Hydrogen Spectrum

Study Materials at Embibe

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