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Methane is the 1st member of alkane groups. This is the simplest form of hydrocarbon and a major constituent of natural gas. It is an organic compound with the chemical formula CH4.
- Methane was first described by the scientist Alessandro Volta.
- The compound belongs to the group-14 hydrides.
- It is a colourless and odourless gas with a sweet oil smell.
- The IUPAC name of the compound is Carbane.
- The structure of the methane molecule is tetrahedral in shape.
- It is the most common ingredient of Greenhouse gases.
- Methane is available in abundance on Earth which makes it an attractive fuel.
- The compound is released during the transportation of fossil fuels.
Key Terms: Methane, Chemical Formula, Alkane, Hydrogen, Carbon, Fossil Fuels, Carbane, Natural Gas, Greenhouse Gases, Biogas, Hydrides, Bemzene, Methyl Groups, Functional Groups
What is Methane?
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Methane is a chemical compound which is composed of the simplest hydrocarbon. Naturally occurring compounds are found below ground under the seafloor.
- The presence of methane in the atmosphere is due to both natural and anthropogenic activities.
- The release or production of methane in the atmosphere is due to the decomposition of organic matter.
- It is also released due to human activities such as agriculture, production of gases, oil, and sewage treatment plants.
- The chemical formula of the compound is CH4.
- Other names of compounds are Carbon tetrahydride, Natural Gas, Carburetted Hydrogen, and Hydrogen Carbide.
Out of all the reactions the methyl group participated in, methylation is one of the most crucial reactions in the human body. Methylation may be defined as the addition or substitution of functional groups with methyl groups.
Methane
Structure of Methane
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Methane will form a tetrahedral structure having four hydrogen atoms linked through a sigma bond to a central atom C. The significance of this structure is that it provides great stability to molecules.
- Methane is usually a less reactive compound.
- It results in the overlapping of valence orbital on carbon and hydrogen atoms.
- The carbon and hydrogen atoms will form an angle of 109 degrees for almost 28 minutes.
- It has a bond length of 1.113 angstroms.
- The compound will form a three-over-one bonding scheme.
Structure of Methane
Sources of Methane
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The source of methane is divided into two categories which are as follows:
Natural Sources
Methane gas is naturally produced in the environment both atmospherically and geologically through the mantle. Marshland, Volcanoes, wet & swampy, and during the digestive process of termites.
Anthropogenic Sources
Anthropogenic sources of methane mean methane produced due to human activities. It include biogas, oils, agriculture, wastelands, and electricity.
Source of Methane
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Properties of Methane
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The main properties of Methane is divided into physical and chemical categories which are as follows:
Physical Properties of Methane
The physical properties of methane are as follows:
- Methane has a sweet taste.
- It is odourless, colourless, and flammable in nature.
- The melting and boiling points of the compound are 90.7K and 111.6K, respectively.
- It has a molecular weight of 16.04g/mol.
- With a specific gravity of 0.554, the compound is lighter than air.
- The compound partially dissolves in water and fully dissolves in organic solvents like toluene, ether, benzene, etc.
The physical properties of methane are tabulated below:
| Category | Data |
|---|---|
| CH4 | Methane |
| Density | 0.656 kg/m³ |
| Molecular Weight | 16.04 g/mol |
| Boiling Point | −161.50 °C |
| Melting Point | −182.5 °C |
Chemical Properties of Methane
The chemical properties of methane are as follows:
Combustion
Methane will undergo a combustion reaction with oxygen and release a large amount of heat. When methane reacts with oxygen, it forms carbon dioxide, water
CH4 + 2O2 ---------→ CO2 + 2H2O + Heat
Steam Reforming
Steam Reforming is a process when methane wil react with water to form carbon monoxide and hydrogen.
CH4 + H20 -----------→ CO + 3H2
CO + H2O --------→ CO2 + H2
Reaction with Halogen
Methane will react halogen to form compound halomethane which take place in presence of ultraviolet rays. It can form compound such as halomethane, dihalomethane, trihalomethane, and tetrahalomethane.
CH4 + Cl2 -------→ CH3Cl + HCl
CH3Cl + Cl2 -------→ CH2Cl2 + HCl
Uses of Methane
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The uses of methane are as follows:
- Methane is used to generate electricity.
- It is used in biofertilizers.
- Highly used as biogas for cooking in a rural area
- In industries, methane is used as an anti-freezing agent.
- One of the important constituents of the compound is LPG and rocket fuels.
- The compound is used to sanitize products.
- It is used as fuel in ovens, homes, water heaters, kilns, and automobiles.
- Methane acts as a reinforcing agent in rubber, thus highly used in vehicle tires.
Use of Methane
Functions of Methane
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The functions of methane are as follows:
- Methane is one of the cleanest burning fossil fuels.
- It has the ability to cut the carbon content when it is produced through non-fossil sources such as green waste and food.
- The heat, light, and mass-energy released are greater than all other hydrocarbons.
- It will comparatively release fewer pollutants into the atmosphere.
- Methyl, as a functional group, plays a vital role in human physiological functions.
- It supports systems like cardiovascular and nervous systems for certain processes.
- At the DNA level, it helps in the regulation of gene expression and the rate of transcription.
- It also acts as a detoxifying agent and helps remove toxic compounds or heavy metals from the body.
Read More:
| Class 10 Chemistry Related Concepts | ||
|---|---|---|
| Structure of Amines | Optical Isomerism | Astatine |
| Aldehyde | Amorphous and Crystalline Solids | Glycogen |
Things to remember
- Methane is the simplest compound that belongs to alkane groups.
- 70% of the compound is produced by human activities.
- The largest source of methane is agricultural land.
- These compounds form enolates and carbanions when treated with strong bases.
- Methanogenesis is sometimes also called biomethanation.
- Active methylene compounds have a methylene bridge between electron-withdrawing groups like nitro and carbonyl.
Sample Questions
Ques: Explain the process of halogenation? (3 marks)
Ans: When the ultraviolet rays are present methane acts as a halogen which forms halomethane. The reaction takes place between methyl radical and halogen radicals formed from methyl and halogens.
- It is a swift reaction where halides replace hydrogen atoms.
- This results in several formations of products, from halomethane to trihalomethane in controlled reactions.
- Formula representation:
X⋅+CH4 → HX+CH3
CH3⋅+X2 → CH3X+X
Ques: Name some properties of methane? (5 marks)
Ans: Some of the chemical and physical properties of methane are as follows:
- The heat is released when methane reacts with oxygen.
- In the presence of natural gas and hydrocarbons, methane can produce hydrogen. This process is called steam reformation.
- It has a tetrahedral molecular formation which has 4 covalent sigma bonds, formed between hydrogen and carbon.
- Methane is entirely soluble in solvents which is natural, including ethanol, benzene, etc., and slightly in water
- Its boiling and melting points are 90.7K and 111.6K, respectively.
Ques: Can methane usage be dangerous? Explain? (3 marks)
Ans: When a person inhales methane, it can adversely affect the health of a human being. It may lead to vomiting, suffocation, dizziness, nausea, headache, loss of judgement, consciousness and coordination.
- This happens as in the enclosed area, methane causes a decrease in the level of oxygen which leads to health degradation.
- Moreover, methane can be explosive if volume increases to 5-14% in the atmosphere.
Ques: Does methane affect the environment? (2 marks)
Ans: Methane interaction with the heat of the sun can lead to the increment of greenhouse gases such as carbon dioxide. The increase in the level of greenhouse gases leads to the depletion of the ozone layer resulting in the rise in temperature. Hence, methane leaks can warm up the atmosphere by absorption.
Ques: What are the factors that produce methane gas? (3 marks)
Ans: The production of methane gas can be from both domestic activities or industrial activities. Methane may be released while producing or transferring natural gases, oil and coal. Methane discharges are likewise brought about by animals and other cultivating exercises and the debasement of rural waste in metropolitan concrete waste landfills.
Ques: Mention the uses of methane? (4 marks)
Ans: The applications of methane include:
- One of the ingredients in fertilizers
- Supply the fuel requirement in oven, automobiles and water heaters
- You can sanitize products with the help of methane
- Used to check gas appliances
- Production of electricity
- In industries,it is utilized as an antifreeze component
- Its refined form is utilized as rocket-fuel
Ques: Describe Biomethanation? (4 marks)
Ans: Biomethanation is an interaction by which organic compounds are microbiologically changed under anaerobic conditions to biogas. Three fundamental physiological gatherings of microorganisms are involved: organic acid oxidizing bacteria, bacteria causing fermentation and methanogenic archaea.
- Microorganisms digest these organic matter by means of a series of biochemical changes to methane and carbon dioxide.
- Biomethanation results in a foul smell and restricts the development of rodents and other kinds of insects.
- The emission of biogas during the process is highly valuable for plants and can be used as manure.
Ques: Describe the terms methylation and demethylation? (4 marks)
Ans: Methylation: Methylation can be described as any process of addition of functional group methyl to chemical compounds or replacement of a functional group with a methyl molecule in a chemical compound. This form of reaction is referred to as an alkylation reaction, wherein a hydrogen atom is substituted by a methyl group.
Demethylation: Demethylation can be described as any process of removal of a methyl group or replacement of a methyl group with some other functional group. In other words, this process is the reverse of the methylation process.
Ques: Explain the functions of methane? (4 marks)
Ans: The function of methane are as follows:
- One of the fossil fuels that burns the cleanest is methane.
- It can reduce the amount of carbon when it is created using non-fossil fuels, including food and green waste.
- Compared to other hydrocarbons, there is an unprecedented emission of heat, light, and mass energy.
- Comparatively speaking, it will emit fewer toxins into the atmosphere.
- As a functional group, methyl is essential to human physiological processes.
Ques: What is the valency of methane? (2 marks)
Ans: Methane do not have any valency because it is a molecule. Atoms have the quality of valency. There are eight valence electrons in all in CH4. It consists of four hydrogen atoms and one carbon atom. The valency of each hydrogen atom is 1, while the valency of the carbon atom is 4.
Ques: How methane contribute to greenhouse gas? (4 marks)
Ans: Natural gas like methane (CH4) is a powerful greenhouse gas (GHG). Greenhouse gasses, which escape into the atmosphere, cover the Earth like a blanket, absorbing light and delaying the release of heat from the globe.
- This energy is exceptionally well absorbed in the case of methane.
- Without this naturally occurring phenomenon, often known as the greenhouse effect, the average temperature of our planet would drop below freezing.
- But during the past few centuries, as greenhouse gas emissions have increased, the greenhouse effect has gotten stronger.
- It is now contributing to global warming at a rate that many find concerning.
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