Uses of Methanol and Ethanol – Structure, Uses and Health Hazards of Methanol and Ethanol, Practice Problems and FAQ

Have you heard the term "biofuels"?

Because fossil fuels are non-renewable and contribute to global warming, biofuels are increasingly being considered as potential alternative fuels for the future.

Ethanol is a clean fuel since it burns completely. As a result, pollution is not noticeably increased. It burns with a clean, smokeless flame, releasing water and carbon dioxide.

2C₂H₅OH+6O₂ → 6H₂O+4CO₂

Typically, ethanol and gasoline are mixed to make "gasohol," which has a 10% ethanol content.

When we use ethanol as a fuel, our reliance on naturally occurring fossil fuels like gasoline declines. In countries like Brazil with limited oil reserves, sugar cane is commonly grown. Sugar cane must be fermented to create ethanol. Ethanol is produced during fermentation, which is used as an alternative fuel source.

Sugar cane is renewable because it can be replaced or regrown. It is also an environmentally friendly fuel source. This is so that the plants can take in carbon dioxide from the air and use it to make the glucose required for fermentation. Green plants employ the carbon dioxide produced by the burning of ethanol to make the glucose needed for the fermentation of ethanol.

We are all accustomed to hearing the word "alcohol." It can refer to many different things, such as a recreational drink, a narcotic, a wood spirit, etc.

With at least one hydroxyl group (-OH) linked to a saturated carbon atom, alcohol is a class of organic molecules with the chemical formula C_n H_2n+1 OH. For instance, methyl alcohol has the chemical formula CH₃OH, while ethanol has the formula C₂H₅OH.

We'll get to know more about the Uses, structure and health hazards of methanol and ethanol on this concept page!

TABLE OF CONTENTS

Methanol – Introduction
Methanol – Uses
Methanol – Health Hazards
Ethanol – Introduction
Ethanol – Uses
Ethanol – Health Hazards
Practice Problems
Frequently Asked Questions – FAQ

Methanol – Introduction

Methanol is also called methyl alcohol, wood alcohol, wood spirit, etc. The most simple aliphatic alcohol and a neutral chemical, methanol has no effect on litmus paper. It has an awful smell and is colourless. Methanol dissolves fully in water. Its boiling point is 337 K.

Until recently, methanol was produced through the destructive distillation of wood. The direct reaction of hydrogen and carbon monoxide gas in the presence of a catalyst is the basis for modern methanol production. A growing amount of methanol is created using syngas, a mixture of hydrogen and carbon monoxide derived from biomass.

It produces explosive combinations when it mixes with air and burns with a nonluminous flame. Ingesting mixes containing it has led to several cases of blindness or death. It is both an intoxicant in alcoholic beverages and a lethal poison.

One carbon, one oxygen, and four hydrogen atoms make up methanol (CH₃OH). Since carbon has a valency of 4, it requires four electrons to complete its octet. By forming covalent bonds with three hydrogen atoms and one oxygen atom of the hydroxyl group, the carbon in methanol completes its octet configuration.

The carbon and oxygen atoms in methanol molecules are sp³ hybridised. The molecule has a tetrahedral structure as a result of sp3 hybridisation, but the bond angle H-O-C is less than 109.5^o because of repulsion between the oxygen's lone pair of electrons.

Methanol – Uses

As a feedstock for chemicals

Methanol is frequently used as a chemical feedstock in the catalytic oxidation process to produce methanal or formaldehyde. Additionally, it is employed in the production of acetic acid. Formaldehyde, which is obtained from methanol, is widely used in the production of plastics, including those used in building materials, car parts, paints, explosives, and wrinkle-resistant imitation textures. Researchers and undertakers both use formaldehyde to preserve cadavers and lab specimens.

As a Solvent

For inks, adhesives, resins, paints and dyes, methanol serves as a solvent. To prevent alcohol abuse, methanol is frequently added to ethanol. It is also employed in the pharmaceutical sector as a solvent. Additionally, it is utilised in screenwash and antifreeze for automobile radiators.

As a fuel

Methanol is a fuel additive that helps gasoline burn more efficiently. Several internal combustion engines can use it as fuel. The following is the equation for methanol combustion:

2CH₃OH+3O₂ → 2CO₂+4H₂O

Biodiesel

Methanol and vegetable oils react to create biodiesel. The main output is a biodiesel-grade methyl ester of a long-chain fatty acid. The reaction results in the production of glycerol as a byproduct. In contrast to raw vegetable oil, which can only be used in modified or vintage diesel engines, biodiesel can be used as a replacement fuel in the majority of modern diesel engines.

Other Applications of Methanol

In the production of resin, dyes, and pharmaceuticals, pure methanol and its derivatives are used. For instance, methanol can be transformed into dimethyl alanine, which is crucial for the creation of dye. In a similar manner, synthetic resins can be produced using formaldehyde produced from methanol.

Methanol has received extensive research as a gasoline substitute in the automotive industry because it is a cleaner and greener alternative to fossil fuels.

Methanol is a reliable organic solvent that can be used to make antifreeze and rocket fuel.

Additionally, it provides energy for cooking fuel.

Because of their sweet aroma, methanol and ethanol are used in perfumery.

Methanol is used as a de-staining agent during polyacrylamide gel electrophoresis in laboratories to get rid of extra stains that could interfere with the observation.

Methanol – Health Hazards

Though the consumption of methanol is rare, its negative effects on the body cannot be overlooked. Methanol is non-toxic in and of itself, but when consumed, it is converted to formic acid in the body. This formic acid is extremely toxic and can cause severe metabolic acidosis. Furthermore, even at low concentrations of 10 mL, methanol can disrupt the optic nerve and cause permanent blindness.

Methanol is oxidised in the body by the alcohol dehydrogenase enzyme in the liver, first to methanal and subsequently to methanoic acid, which can be fatal and result in blindness. Treatment for methanol poisoning involves administering diluted ethanol intravenously to the patient. The kidneys have time to eliminate methanol because the enzyme that converts aldehyde (HCHO) to acid is overworked.

Because ethanol is much safer than methanol, it is used in the manufacture of hand sanitisers.

Ethanol – Introduction

The main component of ethanol is ethane, which has had one of its hydrogen atoms replaced by a hydroxy group. It is a clear, colourless liquid with a pronounced vinous smell and flavour, that is entirely soluble in water.

Distilled spirits, beer, and wine all include ethanol, which is an intoxicating substance.

The two main processes for producing ethanol are ethylene hydration and carbohydrate fermentation, which is the process used to make alcoholic beverages. Using yeast cells, the process of fermentation turns carbohydrates into ethanol.

Sugar crops like beets and sugarcane, as well as grain crops like corn, are the raw materials that are frequently fermented in the manufacturing of industrial alcohol (maize).

It is possible to hydrate ethylene by combining it with a sizable volume of steam, an acidic catalyst, and high pressure and temperature.

Kerosene, benzene or methanol are frequently used to denature ethanol for industrial use, rendering it unfit for human use.

The boiling point of pure ethanol is 78.5 °C. It has a beautiful ethereal aroma and a burning flavour and is a transparent, combustible liquid. The central nervous system is harmed by ethanol. Larger doses impair judgement and coordination, finally resulting in coma and death, but moderate amounts, through reducing inhibitory processes in the brain, relax the muscles and appear to stimulate the body. It is a very addictive chemical for some people, which can result in alcoholism.

The chemical formula of ethanol is C₂H₆O, which contains one oxygen atom and two carbon atoms. A little more information is provided by the structural formula for ethanol C₂H₅OH, which shows that the 2-carbon chain ends in a hydroxyl group (-OH).

Ethanol – Uses

As a Component in Alcoholic Drinks

Over two billion people drink ethanol (also known as ethyl alcohol) every day. Yeast, sugars, and starch are fermented to create this kind of alcohol. Despite the fact that humans have been consuming it for centuries, excessive consumption is harmful to human health. Only a small amount of ethanol can be metabolised by the human liver. Additionally, it affects cognitive and motor abilities and depresses the central nervous system (CNS).

There are two types of alcoholic beverages

a. Distilled Alcohol

A fermented substance is transformed into another substance through distillation, which has an even higher alcohol content. Removing the water and other ingredients from a fermented substance concentrates alcohol. Spirits and liquors are distilled alcoholic drinks. By volume, they have more alcohol than non-distilled beverages. An alcoholic beverage that has been distilled typically has a higher alcohol proof.

b. Undistilled Alcohol

Fermented drinks are another name for undistilled alcohol. The process of fermentation is how bacteria or yeast chemically transform sugar into ethanol. Both beer and wine are fermented, undistilled alcoholic drinks. While breweries ferment barley, wheat, and other grains to make beer, wineries ferment grapes to make wine.

To produce Methylated spirit

Ethanol and methanol are frequently combined. Denaturing ethanol is the name given to this procedure. It is also known as methylated spirit. It is poisonous. Since methylated spirit can burn, it can be used in campfire stoves and lamps.

Ink can be removed from a variety of surfaces, including metals and plastics, using methylated spirit. Methylated spirit is a common ingredient in glass cleaners and other household cleaning supplies.

As a Solvent

In order to dissolve many organic compounds that are insoluble in water, ethanol is used as a solvent. It is a component of paints, cosmetics, detergents, inks, and perfumes.

Due to its ability to inhibit or stop the growth of microorganisms, ethanol has antibacterial properties (germs). The microorganisms' protein shapes are changed, which makes them incapable of carrying out their intended functions. When the bonds holding the protein together to maintain its specific shape are broken, a process known as denaturation takes place. This makes the protein lose its shape. Because of this, ethanol is a component of hand sanitisers and hand wipes.

Some analgesics and mouthwashes use ethanol as a solvent (in concentrations ranging from 1 % to 25 %). Ethanol is a component of cooling baths in many laboratories due to its -114.1^o C melting point. Many spirit thermometers use it as the active fluid as well.

As Fuel

Biofuels are being looked at more and more as potential replacement fuels for the future because fossil fuels are non-renewable and contribute to global warming.

Because ethanol burns completely, it serves as a clean fuel. As a result, it does not significantly increase pollution. It produces water and carbon dioxide as it burns with a clear, smokeless flame.

2C₂H₅OH+6O₂ → 6H₂O+4CO₂

Medical Uses

Alcohol is used in a variety of medical settings as an antiseptic, disinfectant, and antidote in addition to other medical applications. Among other things, alcohol is applied to the skin to disinfect it prior to a needle stick or surgery. Alcohol can be used to clean both the patient's skin and the hands of the medical professionals delivering the treatment. In addition to being used in mouthwashes and toothpaste, it can be used to clean other body parts.

This substance serves a purpose in the medical industry and is frequently found in antibacterial hand sanitiser gels, where its bactericidal and antifungal properties act as antiseptic. Microorganisms are killed by ethanol's antimicrobial properties, which dissolve the lipid bilayer of their membranes and denature their proteins. In addition to being effective against viruses, it also possesses antibacterial and antifungal qualities. It has been demonstrated that ethanol works as an effective antidote for methanol and ethylene glycol poisoning.

Ethanol – Health Hazards

Lethargy, ataxia, recumbency, and vomiting are all signs of ethanol poisoning. In severe cases, symptoms like hypothermia, tremors, acidosis, diarrhoea, seizures, disorientation, vocalisation, hypotension, tremors, tachycardia, and coma can all be fatal. Alcohol makes you throw up by directly irritating your stomach.

Emesis is brought on by excessive alcohol consumption, which increases the blood's ethanol concentration. Vomiting happens when one is intoxicated because of high blood ethanol levels. The muscle becomes paralysed as a result, raising the possibility of aspiration.

Hypoxia is brought on by impaired mitochondrial oxidative function brought on by ethanol intoxication.

Alcohol poisoning results in a drop in body temperature, which leads to hypothermia.

Practice Problems

Q1. Which alcohol is referred to as a wood spirit?

A. Ethanol
B. Methanol
C. Propanol
D. Butanol

Answer: B

Solution: Methanol is also referred to as wood spirit because it was first created by destructively distilling wood.

So, option B is the correct answer.

Q2. Among the following, which is not a use of methanol?

A. Solvent for paints
B. Manufacturing of formaldehyde
C. Antifreeze in car radiators
D. Production of alcoholic drinks

Answer: D

Solution:

Methanol is frequently used as a chemical feedstock in the catalytic oxidation process to produce methanal or formaldehyde.
For inks, adhesives, resins, paints and dyes, methanol serves as a solvent.
Additionally, it is utilised in screenwash and antifreeze for automobile radiators.
Methanol is extremely poisonous; ingesting small amounts can result in blindness while ingesting large amounts can even result in death.

So, option D is the correct answer.

Q3. What are the two main alcohols that are used as fuel in the engine?

A. Butanol and methanol
B. Propanol and butanol
C. Ethanol and propanol
D. Methanol and Ethanol

Answer: D

Solution: Alcohols have long been used as engine fuels; the two most common alcohols used as fuel in engines are methanol and ethanol.

So, option D is the correct answer.

Q4. A reagent that is used in liquid methanol to remove ketones and aldehydes is

A. Manganate
B. Chromate
C. Dichromate
D. Permanganate

Answer: D

Solution: Permanganate is used to remove ketones and aldehydes from depressurised liquid methanol, and a stripper is used to get rid of light ends. High molecular weight molecules are divided using fractionation.

Frequently Asked Questions – FAQ

Q1. At room temperature, why is ethanol liquid?
Answer: Because of the hydrogen bonds that keep the molecules of ethanol closely bound to one another, it is a liquid at room temperature. The oxygen atoms of one molecule form a hydrogen bond with the hydrogen atoms of an adjacent ethanol molecule, which keeps the two molecules tightly bound.

Q2. What is distilled ethanol?
Answer: About 95% of ethanol is present in distilled ethanol, which is typically enough for uses in the chemical, solvent, cosmetic, and pharmaceutical industries. Distillation is unable to provide a higher concentration of ethanol due to its azeotrope point with water.

Q3. What is the purpose of adding ethanol to fuel?
Answer: A biofuel, or one made through the processing of organic material, is ethanol. The auto fuels we frequently use are also referred to as fossil fuels because they are primarily produced by the gradual geological process of fossilisation. In India, fermentation is primarily used to produce ethanol from sugarcane. Because ethanol contains a lot of oxygen, it can burn fuel more completely in an engine.

It can help lower vehicle emissions and can be added to fuel in various amounts. Additionally, because it is made of plants, it is regarded as a renewable fuel.

Q4. What makes methanol so polar?
Answer: Because of the unequal charge distribution of the atoms and its asymmetric molecular geometry, methanol is polar in nature. Because oxygen is more electronegative than hydrogen and carbon, oxygen gains a partial negative charge, and hydrogen and carbon gain a partial positive charge.