Hydrogen is the most prevalent element in the cosmos and the third most plentiful element on the surface of the earth. It is also the simplest element, comprising only one proton and having only one electron in its orbit around the nucleus. In its elemental form, this element occurs as a diatomic molecule, which is H2.
The primary worldwide issue about clean energy necessitates a thorough examination of hydrogen as a separate concept from that of other elements. The usage of hydrogen as an energy source can alleviate this worry to a larger extent.
It also has properties that are similar to both halogens and alkali metals. It has occupied a separate position in the periodic table because of its unique features. It also cannot be found in its natural state in the Earth's atmosphere.
JEE Main Chemistry Chapters 2024
Hydrogen Important Concepts for JEE Main
The Element - Hydrogen
The first element in the periodic table is hydrogen.
Due to its property of supplying electrons (when H+ is generated) and removing electrons (when H- is formed), hydrogen is put in no distinct group.
Group I (Alkali metals) includes hydrogen as follows:
- Like other alkali metals with a (inert gas) 𝜈𝜎1 configuration, it has one electron in its (Outer) shell - 1𝜎1.
- It produces monovalent H+ ions such as Li+ and Na+.
- It has a valency of 1 as well.
- Its oxide (H2O) has the same stability as Na2O.
- It is a good reducing agent (in both the atomic and molecule states), similar to Na and Li.
Hydrogen resembles halogens (Group VII A) in the following ways:
- It is also diatomic Xi2.
- By gaining one electron, it also produces anion H- like F- and Cl-.
- H has a stable inert gas (He) configuration as XH4, and X2H6 has halogens and others.
- Like F Cl, which is also one electron deficient than octet, H is one electron short of duplet (Stable configuration).
- The (IE) of H is comparable to that of halogens.
In comparison to alkali metals, H has an extremely high level (IE). In addition, the size of H+ is quite small when compared to the size of an alkali metal ion.
- Because of its lower electron affinity, H forms stable hydrides only with strongly electropositive metals.
Because of hydrogen's peculiar behaviour, it's difficult to assign it a specific location in the periodic table.
- As a result, it's common to put it in both group I (together with alkali metals) and group VII (Along with halogens).
Position of Hydrogen in the Periodic Table
Hydrogen, with atomic number 1, holds a unique position in the periodic table. It has characteristics that both resemble alkali metals and nonmetals, yet it is not categorized within any specific group. This is due to its isotopic variations and a single electron in its electronic configuration. It is placed above Group 1 (the alkali metals) in the periodic table due to its electron configuration.
Physical Properties of Hydrogen
It's a tasteless, odourless, and colourless gas.
It is water soluble to a degree.
It is extremely flammable.
Atomic radius (pm) – 37
- Ionic radius of H- ion (pm) – 210
- Ionisation energy – 1312 kJ/mol.
- Electron affinity – 72.8 kJ/mol.
- Electronegativity – 2.1
Chemical Properties of Hydrogen
Dihydrogen is a relatively stable gas that only dissociates into hydrogen atoms at temperatures above 2000 K.
H2 → H + H.
It has a very high bond dissociation energy of H, ΔH = 435.9 kJ/mol.
It is not highly reactive due to its high bond dissociation energy. It does, however, mix with a variety of elements or compounds.
Dihydrogen produces interstitial hydrides with transition metals (d-block elements) such as Pd, Ni, and Pt, in which the small molecules of hydrogen occupy the interstitial spaces in the crystal lattices of these hydrides.
Saturated hydrocarbons are formed when H2 reacts with unsaturated hydrocarbons like ethylene and acetylene.
Isotopes of Hydrogen
Hydrogen has three isotopes:
Protium (1H): This is the most common isotope, constituting about 99.98% of naturally occurring hydrogen. It contains a single proton and an electron.
Deuterium (2H or D): Deuterium is a stable isotope of hydrogen and is twice as heavy as protium. It contains one proton, one neutron, and an electron.
Tritium (3H or T): Tritium is a radioactive isotope of hydrogen. It contains one proton, two neutrons, and an electron.
Isotopes have similar chemical properties in general, but there are quantitative differences between them.
Different Forms of Hydrogen
The dissociation of hydrogen molecules produces it.
Atomic hydrogen is extremely reactive and only stays stable for a fraction of a second.
It's made by passing dihydrogen gas through an electric arc formed between two tungsten rods at atmospheric pressure.
The hydrogen gas formed in the reaction mixture when it comes into contact with the substance to be reacted with is referred to as nascent hydrogen.
It's also referred to as "newly born hydrogen." It has higher reactivity than regular hydrogen.
Two atoms make up a hydrogen molecule. The nuclei of both atoms in each hydrogen molecule are spinning.
Ortho hydrogen is a type of hydrogen molecule in which the spins of both nuclei are in the same direction.
Para hydrogen is a type of hydrogen molecule in which the spins of each nuclei are in opposing orientations.
Hydrogen is mostly para hydrogen at 0°K, which is more stable.
The ratio of ortho and para hydrogen is 1:1 at the temperature of air liquefaction.
The ratio of ortho to para hydrogen is 3:1 at ambient temperature.
The ratio of ortho to para hydrogen can never exceed 3:1, even at extremely high temperatures.
Preparation of Hydrogen:
Hydrogen can be prepared through various methods, including:
Preparation of Hydrogen Through Laboratory: It can be generated by the reaction of metals such as zinc or aluminum with dilute acids like hydrochloric acid or sulfuric acid.
Preparation of Hydrogen Through Electrolysis: Water can be electrolyzed to produce hydrogen and oxygen gases. This method is commonly used in industrial settings.
Preparation of Hydrogen Through Steam Reforming: Methane (CH4) is subjected to steam in the presence of a catalyst to produce hydrogen gas. This is a crucial method for large-scale hydrogen production.
Uses of Hydrogen:
Hydrogen has various applications, including:
Chemical Industry: It is used in the production of ammonia (NH3) for fertilizers and in the hydrocracking of fossil fuels to make high-quality fuels.
Fuel Cells: Hydrogen is used as a fuel in fuel cells, which generate electricity through the electrochemical reaction between hydrogen and oxygen.
Space Exploration: It is used as rocket fuel for spacecraft.
Physical and Chemical Properties of Water and Heavy Water:
Physical Properties of Water:
Density: Water has a high density compared to other liquids, which is why ice floats on water.
Specific Heat Capacity: Water has a high specific heat capacity, meaning it can absorb and store a significant amount of heat.
Heat of Vaporization: Water has a high heat of vaporization, which is crucial for its role in cooling and temperature regulation.
Surface Tension: Water exhibits surface tension, which allows small objects to float on its surface.
Chemical Properties of Water:
Solvent Properties: Water is often referred to as the "universal solvent" because it can dissolve a wide range of substances due to its polar nature.
Acid-Base Properties: Water can act as both an acid and a base, leading to the formation of hydronium ions (H3O+) and hydroxide ions (OH-) in aqueous solutions.
Redox Reactions: Water participates in redox reactions, often serving as a reactant in many chemical reactions.
Heavy Water (Deuterium Oxide, D2O):
Heavy water is a stable isotope of water in which the hydrogen atoms are replaced with deuterium (2H).
It has a higher density than ordinary water, and its properties are similar to those of regular water.
Heavy water is used in certain nuclear reactions and as a neutron moderator in nuclear reactors.
Structure, Preparation, Reactions, and Uses of Hydrogen Peroxide:
Structure of Hydrogen Peroxide (H2O2):
Hydrogen peroxide is a bent molecule with an O-O diatomic bond.
It is a pale blue liquid at room temperature and a concentrated solution appears as a colorless liquid.
Preparation of Hydrogen Peroxide:
Hydrogen peroxide can be prepared by the auto-oxidation of 2-ethylanthraquinol, followed by hydrolysis.
It can also be synthesized by the electrolysis of sulfuric acid (H2SO4) in the presence of potassium persulfate.
Reactions of Hydrogen Peroxide:
Decomposition: Hydrogen peroxide decomposes into water and oxygen when exposed to heat, light, or certain catalysts. The decomposition reaction is as follows:
$2H_2O_2 \rightarrow 2H_2O + O_2$
Redox Reactions: Hydrogen peroxide can act as an oxidizing agent, reacting with various substances and reducing itself in the process.
Uses of Hydrogen Peroxide:
Disinfectant: It is used as a disinfectant for cleaning wounds and surfaces.
Bleaching Agent: Hydrogen peroxide is used as a bleaching agent for textiles and hair.
Rocket Fuel: It has been used as a rocket propellant.
Classification of Hydrides: Ionic, Covalent, and Interstitial:
Ionic hydrides are formed by alkali and alkaline earth metals, such as NaH (sodium hydride) and CaH2 (calcium hydride).
They contain hydride ions (H-) and are ionic compounds with a strong metal-hydrogen bond.
Ionic hydrides are highly reactive, particularly with water.
Covalent hydrides are formed by nonmetals like hydrogen and elements of the p-block.
They are covalent compounds, where hydrogen is bonded to nonmetals through shared electrons.
Covalent hydrides are less reactive than ionic hydrides.
Interstitial hydrides are formed by transition metals.
Hydrogen atoms occupy the interstitial sites in the metal crystal lattice.
They have properties intermediate between ionic and covalent hydrides.
Hydrogen as a Fuel:
Hydrogen is considered a clean and efficient fuel source as it produces only water vapor when burned.
It is used in fuel cells to produce electricity through the reaction of hydrogen with oxygen.
Hydrogen fuel cells have potential applications in transportation, power generation, and more.
Industrial Preparation of Hydrogen
The industrial preparation of hydrogen involves various methods, each with its own advantages and limitations. Here are some of the prominent methods used for large-scale hydrogen production:
1. Steam Reforming of Methane:
This is the most widely used method for industrial hydrogen production, accounting for about 80% of global hydrogen production. It involves reacting methane ($CH_4$), the primary component of natural gas, with steam ($H_2O$) in the presence of a nickel catalyst at high temperatures (700-850 °C) and pressures (30-50 bar). The reaction produces a mixture of hydrogen ($H_2$) and carbon monoxide (CO), known as syngas:
$CH_4 + H_2O \rightarrow CO + 3H_2$
The syngas is then further processed to separate the hydrogen and remove impurities. This process typically involves two steps:
Water Gas Shift Reaction: This reaction converts carbon monoxide (CO) into hydrogen (H2) and carbon dioxide (CO2) using steam (H2O) in the presence of an iron oxide catalyst:
$CO + H_2O \rightarrow CO_2 + H_2$
Pressure Swing Adsorption (PSA): This process separates hydrogen from the syngas mixture by selectively adsorbing carbon dioxide and carbon monoxide onto a solid adsorbent at high pressures, allowing pure hydrogen to pass through.
2. Coal Gasification:
This method involves reacting coal with steam and oxygen at high temperatures (1200-1500 °C) and pressures (20-40 bar) to produce a mixture of gases, including hydrogen, carbon monoxide, and carbon dioxide:
$C + H_2O + O_2 \rightarrow CO + H_2 + CO_2$
The syngas produced is then processed similarly to the steam reforming of methane method, involving the water gas shift reaction and pressure swing adsorption to separate and purify the hydrogen.
3. Electrolysis of Water:
This method involves passing an electric current through water to decompose it into hydrogen and oxygen gases:
$2H_2O \rightarrow 2H_2 + O_2$
The process requires an electrolyte, such as sodium hydroxide or sulfuric acid, to conduct the electricity and facilitate the decomposition of water. The hydrogen gas is collected at one electrode, while the oxygen gas is collected at the other electrode. Electrolysis is a more environmentally friendly method for producing hydrogen, as it does not involve the combustion of fossil fuels. However, it is currently more expensive than the steam reforming of methane or coal gasification due to the high energy costs associated with electrolysis.
4. Biomass Gasification:
This method involves converting biomass, such as plant matter or organic waste, into hydrogen through various thermochemical processes, such as gasification or pyrolysis. Gasification involves reacting biomass with steam or oxygen at high temperatures to produce a mixture of gases, including hydrogen, carbon monoxide, and carbon dioxide. Pyrolysis involves heating biomass in an oxygen-free environment to break down the organic matter into gases, liquids, and char. The hydrogen gas is then separated from the other products. While biomass gasification is a renewable and sustainable method for hydrogen production, it is still in its early stages of development and requires further technological advancements to become economically competitive with fossil fuel-based methods.
Choosing the Right Method for Industrial Hydrogen Production
The choice of method for industrial hydrogen production depends on various factors:
The Desired Purity of Hydrogen
The Cost of Production
The Availability of Raw Materials
As the demand for hydrogen increases and technologies continue to develop, new and more efficient methods for hydrogen production are expected to emerge in the future.
Laboratory Preparation of Hydrogen
The laboratory preparation of hydrogen is a common experiment performed in chemistry classes to demonstrate the reactivity of metals and the properties of hydrogen gas. It involves the reaction of zinc (Zn) with dilute hydrochloric acid (HCl) or sulfuric acid ($H_2SO_4$) to produce hydrogen gas ($H_2$) and zinc chloride ($ZnCl_2$) or zinc sulfate ($ZnSO_4$) as byproducts.
Granulated zinc (Zn)
Dilute hydrochloric acid (HCl) or sulfuric acid ($H_2SO_4$)
Collection vessel (e.g., test tube)
Water trough or basin
Step 1: Preparation of the Apparatus
Carefully bend the delivery tube to form an inverted "U" shape. This will allow the hydrogen gas to bubble up through the water and collect in the inverted test tube.
Fill the test tube or other collection vessel with water and place it upright in the water trough or basin.
Step 2: Reaction Setup
Place a small amount of granulated zinc in the flask. Zinc granules provide a large surface area for the acid to react with, increasing the reaction rate and hydrogen production.
Carefully add dilute hydrochloric acid or sulfuric acid to the flask containing the zinc granules. Do not pour the acid directly onto the zinc, as this can cause a sudden and vigorous reaction. Instead, use a glass rod or funnel to gently guide the acid down the side of the flask.
Step 3: Hydrogen Collection
Observe the reaction as the acid reacts with the zinc. Bubbles of hydrogen gas will start to form and rise to the surface.
Position the end of the delivery tube near the bottom of the flask and allow the hydrogen gas to bubble up through the water and collect in the inverted test tube.
Continue observing the reaction until the hydrogen gas production slows down or stops. This indicates that the zinc has mostly reacted with the acid.
Once the reaction has subsided, carefully remove the delivery tube from the water.
To test for the purity of the hydrogen gas, hold a lighted splint near the mouth of the inverted test tube. If the hydrogen gas is pure, the splint will make a popping sound as it ignites.
Hydrogen gas is highly flammable and explosive. Handle it with care and avoid any sources of ignition.
How Can I Create Production of Hydrogen Project For Class 12 and Class 11?
Embarking on a Production of Hydrogen project presents an exciting opportunity for both Class 12 and Class 11 students to delve into the realms of sustainable energy and environmental science. Hydrogen, as a clean and versatile energy carrier, is at the forefront of green technology, making it an ideal subject for exploration.
Production of Hydrogen Project Class 12:
Undertaking a Production of Hydrogen project at the Class 12 level allows students to delve into advanced concepts and methodologies. Here are key aspects to consider:
Explore electrolysis as a method for hydrogen production. Design experiments to investigate the efficiency of electrolysis under different conditions such as varying electrolyte concentrations and temperatures.
Renewable Energy Integration:
Investigate the integration of renewable energy sources, such as solar or wind, into the hydrogen production process. Assess the feasibility and efficiency of using renewable energy for electrolysis.
Explore the role of catalysts in enhancing hydrogen production. Conduct experiments with various catalysts to understand their impact on reaction rates and overall efficiency.
Hydrogen Project Class 11:
For Class 11 students, a Hydrogen project offers an introduction to the fundamental principles of hydrogen production. Here are key components to focus on:
Hydrogen Generation Methods:
Introduce various methods of hydrogen production, including steam methane reforming, biomass gasification, and water electrolysis. Compare these methods in terms of efficiency, cost, and environmental impact.
Emphasize the importance of safety in hydrogen production. Investigate and present safety measures and protocols associated with different production methods.
Explore the diverse applications of hydrogen, from fuel cells to industrial processes. Discuss how hydrogen serves as a clean and sustainable energy source in various sectors.
What is Dihydrogen?
Dihydrogen refers to the molecular form of hydrogen (H2), consisting of two hydrogen atoms bonded together. It is the most common and stable form of hydrogen found under normal conditions. The chemical formula H2 signifies that two hydrogen atoms share a covalent bond, resulting in a diatomic molecule. Dihydrogen is a colorless, odorless, and highly flammable gas. It is the primary component of molecular hydrogen and holds significance in various industrial applications, including hydrogen fuel production, ammonia synthesis, and as a reducing agent in chemical processes. Dihydrogen also plays a crucial role in energy storage and is considered a clean energy carrier due to its potential use in fuel cells for generating electricity.
What are the Properties of Dihydrogen?
Delving into the exploration of properties of Dihydrogen opens a gateway to understanding both the physical and chemical attributes that define this diatomic gas. From its fundamental physical traits to its reactive and combustible nature, the properties of dihydrogen underpin its versatile applications, ranging from industrial processes to clean energy initiatives.
Physical properties of Dihydrogen
Dihydrogen is a colorless, odorless, and tasteless gas, existing in a diatomic molecular form (H2). It has a low density, making it lighter than air. At standard temperature and pressure (STP), dihydrogen is a non-metallic gas with a boiling point of -252.87°C and a melting point of -259.16°C.
Chemical properties of Dihydrogen
Flammability: One of the notable chemical properties of dihydrogen is its highly flammable nature. It forms an explosive mixture with air in specific concentration ranges.
Reactivity: Dihydrogen is a reactive molecule. It readily reacts with many elements and compounds, such as halogens and metal oxides, often acting as a reducing agent.
Combustion: When ignited, dihydrogen undergoes combustion in the presence of oxygen to produce water vapor, releasing a significant amount of energy. This property is harnessed in various industrial applications.
Reduction Reactions: Dihydrogen acts as a powerful reducing agent in chemical reactions. For example, it reduces metal oxides to elemental metals.
Hydrogenation: Dihydrogen participates in hydrogenation reactions, where it adds to unsaturated compounds. This is crucial in processes like the hydrogenation of oils in the food industry.
What are The 20 Uses of Hydrogen?
Hydrogen, as a versatile and clean energy carrier, finds diverse applications across various industries and technologies. Here are 20 notable uses of hydrogen:
Hydrogen Fuel Cells: Powering vehicles and providing electricity in a more environmentally friendly manner.
Ammonia Production: Used in the production of ammonia, a key component in fertilizers.
Petroleum Refining: Hydrogen is crucial for desulfurizing and hydrocracking petroleum products.
Methanol Production: Utilized in the production of methanol, an essential industrial chemical.
Food Processing: Used in the hydrogenation of vegetable oils to produce margarine.
Metal Industries: Employed in the reduction of metallic ores, such as iron ore.
Electronics Industry: Used in the production of semiconductors and flat-panel displays.
Glass Manufacturing: Used in the production of flat glass and other glass products.
Power Generation: Hydrogen can be burned in turbines or engines to generate electricity.
Heat Treatment: Used in heat treatment processes for metals and alloys.
Rocket Propulsion: Used as fuel in rockets due to its high energy content.
Welding: Used as a reducing agent in welding applications.
Laboratory Applications: Used in various analytical instruments and experiments.
Haber Process: Utilized in the synthesis of ammonia through the Haber-Bosch process.
Hydrogen Peroxide Production: Used in the manufacturing of hydrogen peroxide.
Medical Applications: Used in hydrogen-oxygen fuel cells for medical devices.
Breath Hydrogen Tests: Used in medical diagnostics for detecting certain conditions.
Floating Wind Turbines: Hydrogen can be produced using excess electricity from floating wind turbines.
Hydrogen-Powered Vehicles: Fueling vehicles with hydrogen as a clean alternative to traditional fuels.
Hydrogen Blimps and Balloons: Used historically for air travel due to its low density.
JEE Main Hydrogen Solved Examples
Question 1: Under typical circumstances, why does hydrogen exist in a diatomic form rather than a mono-atomic one?
Solution: The K-shell of hydrogen is complete (1s2) in diatomic form, making it highly stable.
Key Points to remember: Hydrogen has 1 electron.
Question 2: Discuss the chemical reactivity of dihydrogen as a result of the high enthalpy of the H-H bond.
Ans: The low chemical reactivity of dihydrogen is a result of the high enthalpy of the H-H bond. This is due to its small atomic size and the H-H bond's short bond length (74 pm). It will take high energy to break the H-H bond in a hydrogen molecule.
Key points to remember: Hydrogen atoms are small in size.
Solved Questions from the Previous Year Question Papers
Question 1: Identify the incorrect statement regarding heavy water.
(1) It reacts with SO3 to form deuterated sulphuric acid (D2SO4).
(2) It is used as a coolant in nuclear reactors.
(3) It reacts with CaC2 to produce C2D2 and Ca(OD)2.
(4) It reacts with Al4C3 to produce CD4 and Al(OD)3.
Solution: In nuclear reactors, heavy water is employed as a moderator to control the speed of neutrons. It isn't used to keep things cool.
As a result, option (2) is the proper response.
Question 2: Calculate the total number of neutrons in three hydrogen isotopes.
Solution: Number of neutrons in three hydrogen isotopes = 0 + 1 + 2 = 3.
As a result, option (3) is the correct answer.
Question 3: Hydrogen peroxide acts both as an oxidising and as a reducing agent depending upon the nature of the reacting species. In which of the following cases does H2O2 act as a reducing agent in acid medium?
Solution: In a redox chemical process, a reducing agent is an element or compound that loses or gives an electron to an electron recipient, the oxidising agent.
H2O2 + MnO4– → Mn+2 + O2
As a result, option 1 is the correct answer.
Question 1: Which hydrogen generators are used?
(4) None of the preceding
Answer: (1) NaH
Question 2: When metal hydride is treated with water, it produces
Answer: (4) Hydrogen.
JEE Main Chemistry Hydrogen Study Materials
Here, you'll find a comprehensive collection of study resources for Hydrogen designed to help you excel in your JEE Main preparation. These materials cover various topics, providing you with a range of valuable content to support your studies. Simply click on the links below to access the study materials of Hydrogen and enhance your preparation for this challenging exam.
JEE Main Chemistry Study and Practice Materials
Explore an array of resources in the JEE Main Chemistry Study and Practice Materials section. Our practice materials offer a wide variety of questions, comprehensive solutions, and a realistic test experience to elevate your preparation for the JEE Main exam. These tools are indispensable for self-assessment, boosting confidence, and refining problem-solving abilities, guaranteeing your readiness for the test. Explore the links below to enrich your Chemistry preparation.
Thus, among all the elements found in nature, hydrogen has the simplest atomic structure. It is made up of simply one proton and one electron in its atomic form. It is known as hydrogen in its elemental form, where it occurs as a diatomic (H2) molecule. It has the most number of compounds of any element. Do you know that the usage of hydrogen as a source of energy can help to alleviate some of the world's energy concerns? In fact, as known from this article, hydrogen is extremely important in the industry.