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Hydrogen - Notes, Topics, Books, FAQs

Hydrogen - Notes, Topics, Books, FAQs

Edited By Team Careers360 | Updated on May 06, 2022 02:23 PM IST

Hydrogen is the smallest and lightest element in the universe among all the elements discovered so far. It has one electron and one proton. It has three isotopes, i.e protium, deuterium, and tritium. It is also an important part of many biomolecules like proteins, DNA, carbohydrates, etc. In nature, it is available as natural gas but in pure form, it is highly inflammable. In the modern periodic table, its position is not fixed because it belongs to s-block but its properties resemble the non-metals.

Hydrogen has various important real-life applications as mentioned below:

  • In petroleum refinery, it is used to remove sulfur content. In these plants, it is also used for hydroisomerization.
  • In ultraviolet lamps, it is used in the form of deuterium. These lamps on heating produce light in the ultraviolet region.
  • One of the first use of hydrogen is its use in gas balloons. Due to its light weight, it is used for flying the hot balloons.

Notes for Hydrogen

In this section, you will study about the important topics of the chapter, overview, formulae and some important tips and guidelines for the preparation of the chapter at the best.

Hydrogen- Important Topics

  • The position of Hydrogen in the periodic table
  • Isotopes of Hydrogen
  • Dihydrogen
  • Hydrides
  • Water
  • Hydrogen Peroxide
  • Dihydrogen as a fuel

Overview of the Chapter

Hydrogen is one of the important element in the universe. In nature, it exists in dihydrogen form as H2. In this article, you will study the various insights about this chapter and preparation tips.

The position of Hydrogen in the periodic table:

Hydrogen is placed in the first position of the periodic table. However, its actual position is always has been a matter of discussion in science. Its electronic configuration is 1s1, which means either it requires one more electron to completely fulfill the s orbital or it can lose one electron. Thus Hydrogen behaves like alkali metals and halogens. Like alkali metals, Hydrogen forms halides, oxides, and sulphides. But in terms of ionization enthalpy, Hydrogen resembles more to halogens than alkali metals.

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Isotopes of Hydrogen:

As you all must know from your earlier classes, Hydrogen has three isotopes: protium, deuterium and tritium. Protium has no neutron, deuterium has 1 neutron and tritium has 2 neutrons. Since the electronic configuration of all these isotopes is same therefore chemical properties of these isotopes are same. However, their physical properties are considerably different from each other.

Dihydrogen
Dihydrogen is one of the most important chemicals in the universe. It is the most abundant element in the universe with almost 70% mass of the universe. In this section, you will study the preparation of dihydrogen, its properties, and uses.

  • Preparation:
    Hydrogen is prepared by the reaction of granulated zinc with hydrochloric acid or with aqueous alkali.
    \\*Zn\: +\: 2H^{+}\: \rightarrow \: Zn^{2+}\: H_{2}\\*Zn\: +\: 2NaOH\: \rightarrow \: Na_{2}ZnO_{2}\: +\: H_{2}
  • Properties of Dihydrogen
    (i) Physical properties:
    (a) It is colourless, tasteless, combustible gas.
    (b) It is almost 1/4 times lighter than air.
    (c) It is very low solubility in water.
    (ii) Chemical Properties:
    The bond dissociation enthalpy of dihydrogen is very high thus, it is very inert at room temperature.
  • Reaction with halogens:
    It reacts with halogens and forms hydrogen halides of the form HX.
    H_{2}(g)\: +\: X_{2}(g)\: \rightarrow\: 2HX(g)
  • Reaction with dioxygen:
    It reacts with dioxygen and forms water.
    2H_{2}(g)\: +\: O_{2}(g)\: \rightarrow\: 2H_{2}O(l)
  • Reaction with dinitrogen:
    It reacts with dinitrogen and forms ammonia:
    3H_{2}(g)\: +\: N_{2}(g)\: \rightarrow\: 2NH_{3}(g)
  • Reaction with metals:
    It reacts with metals and forms hydrides
    H_{2}(g)\: +\: 2M(g)\: \rightarrow\: 2MH(s)
  • Uses
    (i) It is used in the synthesis of ammonia.
    (ii) It is used in the manufacture of vanaspati fat.
    (iii) It is used in the production of metal hydrides.
    (iv) It is also used for the synthesis of hydrogen chloride.

Hydrides

Water
Water is present on the earth in a tremendous amount. In the human body, it is available up to 70% and in some fruits like watermelon, it is present up to 96%. On earth, it is present in various forms as given in the table:

Source

Total(%)

Oceans

97.33

Saline lakes and inland seas

0.008

Polar ice and glaciers

2.04

Groundwater

0.61

Lakes

0.009

Soil moisture

0.005

Atmospheric water vapour

0.001

Rivers

0.0001

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Water has the bent structure with 104.50 bond angle and 2 lone pair of electrons on the oxygen atom. It is a highly polar molecule and forms hydrogen bonding with other water molecules. The structures of water are depicted in fig below:

Physical properties

  • It is a colourless liquid.
  • It's melting point is 0oC and boiling point is 100oC.
  • It is an excellent solvent for the transportation of ions and molecules.
  • It has a high heat of vaporisation and high heat capacity.
  • It has higher specific heat, thermal conductivity, surface tension, etc.

Chemical properties

  • Amphoteric nature
    Water is amphoteric in nature. Thus it has the ability to act as an acid as well as a base.
  • Redox reactions with water
    Water is reduced very easily on reacting with highly electropositive metals.
    2H_{2}O(l)\: +\: 2Na(s)\: \rightarrow \: 2NaOH(aq)\: +\: H_{2}(g)
  • Hydrolysis reaction
    Some covalent and ionic compounds are hydrolysed in water.
    \mathrm{P_{4}O_{10}(s)\, +\, 6H_{2}O(l)\, \rightarrow \, 4H_{3}PO_{4}(aq)}

Hard and Soft Water
When salts of calcium and magnesium are dissolved in the water then it is called as hard water, but when these salts are not present in the water then it is known as soft water. Hard water does not form lather with soaps but soft water forms lather. For washing in hard water, soaps are not efficient and thus we use detergents. With proper water treatment, this hardness of water can be removed.

Hydrogen Peroxide(H2O2)
Hydrogen peroxide is one of the most important compound which is used in the pollution control treatment. Some of the important physical properties of hydrogen peroxide are given in the table as below:

Melting Point(K)

272.4

Boiling Point(K)

423

Vapour pressure

1.9

Density

1.64

Dielectric Constant

70.7

Electrical Conductivity

5.1x10-8

NCERT Notes Subject Wise Link:

  • NCERT notes Class 11 Maths
  • NCERT notes Class 11 Physics
  • NCERT notes Class 11 Chemistry
  • NCERT notes Class 11 Biology
  • Preparation: Hydrogen peroxide is prepared by the following methods as discussed below:
    (i) In this method, barium peroxide is treated with sulphuric acid and thus form barium sulphate and hydrogen peroxide.

    \mathrm{BaO_{2}.8H_{2}O(s)\: +\: H_{2}SO_{4}(aq)\: \rightarrow\: BaSO_{4}(s)\: +\: H_{2}O_{2}(aq)\: +\: 8H_{2}O(l)}

    (ii) In this method, with the help of electrolytic oxidation of acidified sulfate solutions, peroxodisulphate is obtained. This peroxodisulphate is then hydrolyzed to yield hydrogen peroxide.
    \mathrm{2HSO_{4}^{-}(aq)\, \overset{Electrolysis}{\rightarrow}\, HO_{3}SOOSO_{3}H(aq)\overset{Hydrolysis}{\rightarrow}\, 2HSO_{4}^{-}(aq)\, +\, 2H^{+}(aq)\, +\, H_{2}O_{2}}
  • Uses
    (i) In daily life, hydrogen peroxide is used as a hair bleach.
    (ii) It is used in the synthesis of tartaric acid and some food products.
    (iii) It is used a bleaching agent for textiles, leather, fats,etc.
    (iv) It is used to manufacture chemicals like sodium perborate and per-carbonate.

Dihydrogen as a fuel

Dihydrogen can be used fuel as on combustion it produces a tremendous amount of heat. The combustion of dihydrogen can produce almost three the energy as produced by petrol. Also, the pollutants released are also lesser than petrol. The only pollutant from dihydrogen released is oxides of dinitrogen, but this problem can be solved very easily by using a little amount of water. This addition of water will reduce the temperature and thus the reaction between nitrogen and oxygen will not take place.
But using dihydrogen gas as a fuel has some limitations. The cylinder of compressed dihydrogen gas weighs almost 30 times heavier than a petrol tank. Also, converting dihydrogen to the liquid state requires cooling to 20K. Thus it requires expensive insulated tanks.

NCERT Solutions Subject wise link:

NCERT Exemplar Solutions Subject wise link:

How to prepare for Hydrogen?

  • This chapter is a part of inorganic chemistry. It is completely theory-based and very easy to learn, there is no need to memorize any formula.

  • Before reading this chapter, first, you must have the basic knowledge of chapter - periodic classification of elements.

  • Rest this complete chapter is very simple, just be regular and be consistent in your numerical practice.

Prescribed Books

First, you must finish the class XI and XII NCERT textbook and solve each and every example and unsolved question given in it. Then for advanced level preparation like JEE and NEET, you must follow O.P. Tandon. You must definitely solve the previous year papers. Meanwhile, in the preparation, you must continuously give the mock tests for the depth of knowledge. Our platform will help you to provide with the variety of questions for deeper knowledge with the help of videos, articles and mock tests.

Also Read

Hard Water and Soft Water

20 Sep'24 11:42 AM

Isotopes of Hydrogen: Definition, Diagram and Examples

20 Sep'24 11:02 AM

Dihydrogen

20 Sep'24 11:01 AM

Hydrides: Properties, Reactions & Uses - Britannica

20 Sep'24 10:57 AM

Importance of Water

20 Sep'24 10:54 AM

Hydrogen Peroxide

20 Sep'24 10:51 AM

Hydrogen - Notes, Topics, Books, FAQs

06 May'22 02:23 PM

Articles

Questions related to

Question : If the density of oxygen is 16 times that of hydrogen, what will be their corresponding ratio to the velocity of sound?

Option 1: 4:1

Option 2: 2:1

Option 3: 1:16

Option 4: 1:4

Correct Answer: 1:4


Solution : The correct option is 1:4.

If the density of oxygen is 16 times that of hydrogen, the ratio of their velocities of sound will be the same as the ratio of their densities

The velocity of sound from oxygen to hydrogen is 1:4.

v=√γP/ρ.

  • v is the speed of sound in the gas,
  • γ is the heat capacity ratio 
  • P is the pressure of the gas, and
  • ρ is the density of the gas.

Vo2/VH2 = ρH2/ρO2

√1/16 = 1/4​​.

Read Complete Answer
Team Careers360 26 January,2024

Question : Comprehension:
Read the given passage carefully and answer the questions that follow.
If you pay close attention to soap advertisements, you may hear of its pH value being claimed to be perfect for human skin. But is there really such a thing? Let's start at the beginning. pH (potential hydrogen) is defined as the concentration of hydrogen ions in a solution. pH values range between 0 and 14.7 is the neutral point, 0 being the most acidic and 14 being the most alkaline. More importantly, your skin isn't exactly pH 5.5; it falls in a range between 4.0 and 7.0, depending on diverse factors like the body part, age, genetics, ethnicity, and environmental conditions.

So, are products formulated at pH 5.5 perfect for skin? The short answer: not really! First, parameters like texture and other ingredients indicate a cleanser's quality, much better than pH alone. Second, though the skin pH rises slightly immediately after cleaning even with plain water, it reverts to its mild acidic pH in an hour. Healthy skin quickly rebalances the 'acid mantle' - a protective layer over the skin—and is unaffected in the long term by the cleanser's pH. Skin modulates pH, making skin products function optimally. So, why market pH 5.5 products as "perfect"? Well, for certain skin types (e.g., oily skin) and certain skin conditions (like acne), an increase in pH can aggravate these skin situations. This might lead to an interpretation that a skin care product needs to be at a pH for optimum cleansing. Hence, skincare experts have expressed reservations about pH being the sole criterion of product safety and 'acid mantle' preservation when factors including plain water may contribute to the same. Thus, an ideal product is almost impossible to define. So, look well beyond pH alone.

Question:
According to the passage, the pH value of human skin is generally:

Option 1: between 7 and 14

Option 2: 5.5

Option 3: between 0 and 7

Option 4: between 4 and 7

Correct Answer: between 4 and 7


Solution : The correct choice is the fourth option.

Explanation: According to the passage, the pH value of human skin is generally in a range between 4.0 and 7.0, depending on various factors like body parts, age, genetics, ethnicity, and environmental conditions.

Therefore, the correct answer is, between 4 and 7.

Read Complete Answer
Team Careers360 24 January,2024

Question : Directions: In the following question, some statements are given, each followed by some conclusions. You have to consider the statement to be true, even if it seems to be at variance from commonly known facts. You have to decide which of the given conclusions, if any, follows from the given statements. 
Statement: The successful test of the Hydrogen bomb of North Korea is a threat to the United States and its ally countries.
Conclusions:
I. North Korea will declare a state of war against the US and its ally countries soon.
II. The US and its ally countries should not worry about North Korea's successful test of a Hydrogen bomb as it has only increased its nuclear arsenal.

Option 1: Only I follows

Option 2: Only II follows

Option 3: Neither I nor II follows

Option 4: Both I and II follow

Correct Answer: Neither I nor II follows


Solution : According to the above-given statement –
Conclusion I: North Korea will declare a state of war against the US and its ally countries soon – Though North Korea has successfully tested a hydrogen bomb, it does not imply that North Korea will declare a state of war as it could be for any other purpose as well.
Conclusion II: The US and its ally countries should not worry about North Korea's successful test of a Hydrogen bomb as it has only increased its nuclear arsenal – It's not confirmed from the above statement that North Korea will never attack the US and its ally countries and this test has only been done to increase its nuclear arsenal. Any motive can be there behind this successful test.

Therefore, the correct answer is neither conclusion I nor conclusion II. Hence, the third option is correct.

Read Complete Answer
Team Careers360 22 January,2024

Question : Which of the following is an air pollutant?

I Water vapour

II Carbon dioxide

III Hydrogen Gas

Option 1: Only I

Option 2: Only II

Option 3: Only III

Option 4: Both II and III

Correct Answer: Only II


Solution : The correct option is Only II.

Carbon dioxide (CO2) is classified as an air pollutant when it is found in high concentrations in the Earth's atmosphere, causing harmful impacts on the ecosystem, and climate. Human actions such as fossil fuels, have considerably boosted its concentration. The fundamental issue with increasing CO2 levels as an air pollutant is its role as a greenhouse gas, which leads to global warming.

Read Complete Answer
Team Careers360 22 January,2024

Question : How many hydrogen atoms are there in a molecule of methane?

Option 1: 2

Option 2: 6

Option 3: 4

Option 4: 3

Correct Answer: 4


Solution : The correct answer is 4.

Comprising one carbon atom and four hydrogen atoms, methane (CH4) is a colourless, odourless and extremely combustible gas. Burning it with oxygen yields carbon dioxide and water vapour. It can be made synthetically or naturally.

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Team Careers360 20 January,2024
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