Nitrous Oxide - Introduction, Structure, Preparation, Properties, Applications, Practice Problems, FAQs

Try to envision a picture of an auditorium full of royal and political dignitaries!

They gathered together for a luncheon to discuss some serious subjects of public interest. All of a sudden the vibe of the ambience starts shifting from sheer seriousness to soft giggles and laughter.

Gradually the invitees start laughing out louder than ever and the weirdest part is that no one is even aware of the cause of such a laughter outbreak. Finally, the meeting had to be called off and later it was discovered that some opposition parties tried to intentionally disrupt the meeting by using such a ‘funny’ strategy and the root of all the fun that took place was an invisible chemical, a gas, named, “Nitrous Oxide”- The so-called ‘laughing gas’.

Well, the situation portrayed is completely fictitious (and take no offence please!), but the characteristics of the gas that was made to use, are a reality! In fact, nitrous oxide induces a sudden sense of euphoria and causes laughter. Not just that, it has amazing anaesthetic properties too, which is why it is used for relieving pain in some medicinal procedures like dentistry and childbirth.

Most people often go through five stages of sedation: lightheadedness, tingling in the arms and legs, warmth, bliss, and finally sleepiness! Indeed the facts and properties of this gas are very interesting. Let’s find out more about it.

TABLE OF CONTENTS

Nitrous Oxide-Introduction
Structure and Oxidation state of Nitrous Oxide
Preparation of Nitrous oxide
Properties of Nitrous Oxide
Applications of Nitrous Oxide
Practice Problems
Frequently Asked Questions-FAQs

Nitrous Oxide-Introduction

Joseph Priestley in the year 1772 was the first to discover nitrous oxide. Nitrous oxide is a dinitrogen oxide having the chemical formula N₂O. At ambient temperature, it is colourless and it is non-flammable. It is also known as ‘laughing gas’.

Due to its anaesthetic and pain-reducing properties, nitrous oxide has numerous medical applications, particularly in surgery and dentistry. Humphry Davy gave it the nickname "laughing gas" because it causes euphoria when inhaled, a characteristic that has led to its usage as a dissociative anaesthetic for amusement.

It is commonly called as dinitrogen oxide, hyponitrous oxide and dinitrogen monoxide.

N2O is insoluble in water and at higher temperatures, acts as a potent oxidant.

Nitrous oxide smells quite pleasant and it's a colourless gas. It produces excitement and merriment once inhaled in very little amounts.

It is the world's most used inhaled anaesthetic because it relieves pain quickly. Consumption at greater doses can have possible narcotic effects and can cause death by suffocation. Laughing gas is basically N₂O.

Structure and Oxidation state of Nitrous Oxide

Let the oxidation state of N in N₂O be 'x'.

So, 2x+(-2)= 0

∴ x= +1

Hence oxidation state of N in this oxide of nitrogen is +1.

The structure of nitrous oxide can be represented as a resonance hybrid of the following structures:

Preparation of Nitrous oxide

Commercial Method of Preparation:

N₂O can be prepared by decomposition of ammonium nitrate (NH₄N_O3) industrially.

The nitrate of ammonia is always used to make nitrous oxide. The purity of the salt must be taken into consideration; it should not contain ammonia hydrochlorate.
It is created by mixing pure nitric acid with pounded carbonate of ammonia. Concentrated nitric acid may be pre-diluted with half its volume of water as long as there is effervescence and a small amount of carbonate may be left in the liquid at the conclusion.
When the solution's boiling point rises over 250°C and a drop of it touches a cool glass plate, it solidifies.
A portion of this salt is added to a retort and heated by a charcoal portable chafing dish (or heater), whose diffused heat is preferable to the heat from the lamp, in order to produce nitrous oxide.
On applying temperatures above 340oC, ammonium nitrate boils and begins to decompose, releasing nitrous oxide (N₂O) and water. Since cold water absorbs most of it, nitrous oxide has to be collected in a gasometer filled with water at about 90oC.
The entire salt undergoes the same breakdown, leaving nothing in the retort.

Additionally, nitrous oxide is formed when the salt nitrogen sulphate of ammonia is added to acid and when it is dissolved in dilute nitric acid, but subsequent operations do not provide the gas in its pure form.

Laboratory Methods of Preparation:

A mixture of sodium nitrate and ammonium sulphate can also be heated to produce.

2NaNO₃ + (NH₄)2SO₄ → Na₂SO₄ + 2N₂O + 4H₂O

A manganese dioxide-bismuth oxide catalyst has been reported to directly oxidise ammonia.

2NH₃ + 2O₂ → N₂O + 3H₂O

Nitrous oxide is produced when sodium nitrite and hydroxylammonium chloride interact.

NH₃OHCl + NaNO₂ → N₂O + NaCl + 2H₂O

It has also been shown to create nitrous oxide when HNO₃ is treated with SnCl₂ and HCl.

2HNO₃ + 8HCl + 4SnCl₂ → 5H₂O + 4SnCl₄ + N₂O

With a half-life of 16 days at 25 °C and pH 1-3, hyponitrous acid breaks down into nitrous oxide and water.

_H2N₂O₂→ H₂O + N₂O

Properties and Reaction of Nitrous Oxide

N₂O is a colourless, non-flammable gas that tastes and smells mildly sweet at normal temperature.
Nitrous oxide is a potent oxidizer at high temperatures, much like molecular oxygen.
Nitrous oxide can relight a blazing splint by promoting combustion by releasing the dipolar bound oxygen radical.
It is a stable and relatively unreactive gas.
It is colourless and a neutral oxide.
Its boiling point is -88.48 °C and its melting point is −90.86 °C.
Its molar mass is 44.013 g mol^-1.
Density of nitrous oxide is 1.98 kg m^-3.

Nitrous oxide reacts with sodium amide (NaNH₂) to form sodium azide (NaN₃), ammonia and sodium hydroxide.

2NaNH₂+N₂O NaN₃+NH₃ +NaOH

Applications of Nitrous Oxide

In rocket motors, it serves as an oxidizer.

It is used as a culinary component and as an aerosol spray propellant.

It is a substance used in the manufacturing of semiconductors.

In medicine, it serves as an anaesthetic and analgesic.

It is used as a flavouring component.

It is used as a gasoline additive in cars.

In addition to producing several compounds, it is employed in dental operations and treatments.

The food business also makes use of nitrous oxide.

It contributes to the amount of aerosol whipped cream.

It serves as the propellant in cooking spray. To protect your potato chips from getting crushed, it is used to make potato chip bags puffy.

Medicinal Use: Women can utilise nitrous oxide during labour, and hospitals and birthing facilities are using it more frequently. Although it doesn't completely eliminate the pain, it helps lessen its intensity. It can be used at any point during labour, has no harmful side effects, doesn't call for an intravenous (IV) or catheter, and allows women to continue moving around while giving birth.

When your child visits the dentist, nitrous oxide is thought to be extremely safe to use. They can relax because of it. He or she can continue to be awake as the dentist fills the cavity since once it is switched off, it is promptly flushed from the body. However, smaller kids might not want to use the nitrous oxide mask, and it might make some kids feel nausea. Before administering nitrous oxide to your child, consult a general dentist.

Actually, the nitrous oxide used at the dentist is often a blend of 70% oxygen and 30% nitrous oxide. The ratio is frequently 50/50 for medicinal purposes.

Practice Problems

Q. 1. Many substances easily burn in the presence of nitrous oxide (N₂O) instead of air. This is due to:

Activation energy is elevated on increasing the temperature
It is reactive at very high temperatures
It can dissociate to give oxygen
Dissociated to form more nitrogen than in air

Answer: (C)

Solution:

Nitrous oxide dissociates to form N₂ and O₂ as it is itself unstable. So it readily produces oxygen which is a supporter of combustion.

So, option (C) is the correct answer.

Q.2. The oxidation state of nitrogen in nitrous oxide is:

+1
+2
-1
-2

Answer: (A)

Solution: Let the oxidation state of N in N₂O be 'x'.

So, 2x+(-2)= 0

∴ x= +1

Hence, the oxidation state of N in this oxide of nitrogen is +1. So the correct answer is option A.

Q.3. N2O is a:

Acidic oxide
Neutral oxide
Basic oxide
Amphoteric oxide

Answer: (B)

Solution:

Nitrous oxide does not react with a base or an acid and hence it is termed as a neutral oxide. So option B is the correct answer.

Q.4. In the medicinal field, nitrous oxide is used as:

Antipyretic agent
Anti-inflammatory agent
Analgesic and Anaesthetic agent.
None of the above

Answer: (C)

Solution:

Option (C) is the correct answer. General anaesthesia, procedural sedation, dental anaesthetic, and the management of excruciating pain are all possible uses of nitrous oxide gas. Nitrous oxide's powerful analgesic effects can be effective in providing analgesia in settings such as the obstetrical ward or emergency room.

Frequently Asked Questions-FAQs

Q.1. Can nitrous oxide cause allergic reactions during dental procedures?
Answer: Nitrous oxide is not an allergen for everybody. It is safe for those with diabetes, epilepsy, liver, heart, or cerebrovascular illness, but you should talk to your dentist if you have a respiratory condition.

Q.2. What is the longevity of the anaesthetic effect of nitrous oxide
Answer: Nitrous oxide has an immediate sleepy effect that dissipates as soon as the gas is shut off. The time it takes for sedation to take effect can range from 30 seconds to three or four minutes.

Q.3. Is nitrous oxide responsible for global warming?
Answer: Nitrous oxide N₂O makes up 6% to the greenhouse effect, which is the largest contributor. Nitrous oxide absorbs radiation and retains heat in the atmosphere, where it can survive for an average of 114 years, just like other greenhouse gases.

Over a period of 100 years, one pound of N₂O heats the atmosphere 300 times more than one pound of carbon dioxide does. N₂O is a risky climate change contributor due to its strength and lengthy life. It ranks third among the greenhouse gases that cause global warming in our atmosphere, behind only CO₂ and methane.

Q.4. What are the natural sources of N₂O?
Answer: Natural sources of nitrous oxide emissions include the soil, oceans, and atmosphere of the planet. Nitrous oxide is produced more from human sources than from natural emissions. Modernising technology and converting to alternative fuels are efficient strategies to lower nitrous oxide emissions from industry, which are typically produced by the combustion of fossil fuels.