Air Composition Properties

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Composition of Air

The world we reside in is covered with air, called the atmosphere. Our atmosphere is composed of several gases. The gases it contains are:

  • Nitrogen

  • Oxygen

  • Argon

  • Carbon Dioxide

  • Neon 

  • Helium 

  • Hydrogen

  • Ozone, etc.

The most important gases are Oxygen, Nitrogen, and Carbon Dioxide. Air also contains water vapor and dust particles.

By volume, 78.084% of N2, 20.946% of O2, and 1% of trace gases together; these gases make the atmosphere. Trace gases are lesser in volume, but they are essential to us. The following diagram shows the constituents of air.

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What is the Composition of Air?

What do we take in for survival? We intake the oxygen. However,  the air we breathe doesn’t contain oxygen only; it has a composition of several gases. The characteristics of these gases are:

  1. Nitrogen & oxygen are present in bulk in the atmosphere.

  2. Carbon Dioxide, Helium, Ozone, Argon are present in a lesser amount.

  3. Minute dust particles are also present in the atmosphere.

  4. Plants require nitrogen for their survival, which they can’t take directly, so they take CO2 from the atmosphere. 

Therefore, bacteria present in the soil and the roots of plants take N2 and convert it into the form that is usable for plants.

Nitrogen is the plenteous gas in the atmosphere. Now, we will talk about other essential gases.


Oxygen

  • Oxygen is the second most copious gas in the air.

  • During photosynthesis, plants release oxygen in the atmosphere.

  • Humans and other living creatures take in oxygen for their survival.


Carbon Dioxide

  • Carbon dioxide is another essential gas in the atmosphere after N2 and O2.

  • Green plants utilize carbon dioxide (CO2) to prepare their food and release O2 in the atmosphere.


Point to Ponder:

The amount of carbon dioxide expelled by humans or other living beings appears to be equivalent to the amount used by the plants, thereby making an exact balance in the atmosphere. However, this statement doesn’t maintain verity, do you know why?


If We Talk about the Below-mentioned Factors:

  • Industries

  • The burning of fossil fuels

  • Release of carbon dioxide by living beings.

The continuous discharge/emission of carbon dioxide is producing (creating) an imbalance in the atmosphere. That’s why the above statement is wrong.


Chemical Composition of Air

 The table lists the chemical composition of air:


Important Gases


Name of the Gas

Chemical Formula

In Percentage

In ppmv

Nitrogen

N2

78.084

780,840

Oxygen

O2

20.946

209,460

Carbon Dioxide 

CO2

0.039445 〜 0.04

394.45 〜 400

Trace Gases (out of 1%)

Helium 

He

0.00052

5.24

Neon 

Ne

0.001818

18.18

Argon 

Ar

0.934

9,340

Krypton 

Kr

0.00011

1.14

Methane

CH4

0.000179

1.79

Hydrogen

H2

0.000055

0.55

Xenon 

Xe

0.000009

0.09

Ozone

O3

0.0-0.000007

0.0-0.07

Carbon Monoxide

CO

0.00001

0.1

Nitrogen Dioxide

NO2

0.000002

0.02


The gases mentioned in the table are also known as the Principal Gases of Air.


Air and its Properties

Air has the following properties:

  1. Air takes up volume.

Air takes up the volume of the container it is kept in.

  1. Air has mass/weight.

Take a balloon, measure its weight. Now, fill another balloon with air and measure its weight. You will note a difference in their weights.

  1. Air is affected by altitude/height.

The higher we go, the lower is the air pressure. Everest climbers use oxygen tanks because, at higher altitudes, the oxygen becomes thin. These tanks help climbers breathe normally. 

  1. Air is affected by temperature.

Higher is the temperature of the air, the faster the motion of air molecules.

  1. Air exerts pressure in all directions.

On shaking the cold-drink bottle and removing its cap, carbon dioxide comes out with pressure and spreads in all the directions.

  1. Air is compressible.

Carbon dioxide inside the cold-drink bottle comes out with pressure on removing the cap of the bottle.


The Table Below Shows the Properties of Air:

Parameters

Value

Density 

1.229 kgm⁻³

Pressure 

1.013 kN/m²

Specific Volume

0.814 m³/kg

Temperature

15⁰C / 288 K

Specific heat ratio

1.4

Gas Constant

0.286 J/g/K

Viscosity

1.73 x 10⁻⁵N - s/mc

Molecular Weight 

28.97 grams per mole

Thermal Conductivity at 0 ⁰C

24.35 W/mK

Thermal Conductivity at 20 ⁰C

0.026 W/m/K

Gravity Acceleration

9.8 ms⁻²

Specific heat capacity (CP)

1.006 kJ/kgK

Specific heat capacity (CV)

0.7171 kJ/kgK

Enthalpy at 0 ⁰C

11.57  kJ/mol or 399.4  kJ/kg

Entropy at 0 ⁰C

0.1100 kJ/mol K or 3.796 kJ/kg K 

Triple Point Temperature

59.75 K or - 213.40 ⁰C or - 352.12°F

Triple Point Pressure

0.05196 atm

0.05265 bar 

5265 Pa 

0.7636 psi

FAQ (Frequently Asked Questions)

Question 1: Write the Chemical Properties of Carbon Dioxide?

Answer: The properties are:

  1. It is colorless.

  2. It is odorless at low concentrations.

  3. It has a sharp, acidic smell at higher concentrations.

  4. At standard temperature & pressure (STP),  the density of CO₂ is 1.98 kg/m³.

Question 2: Write the Properties of Nitrogen.

Answer: The properties of N₂ are:

  1. N₂ gas is inert, nonmetallic, odorless, and tasteless.

  2. Its atomic number is 7, with an atomic mass of 14.0067.

  3. The density of N₂ at 0 ⁰C is 1.251 g/liter.

  4. Its specific gravity is 0.96737.

Question 3: Write the Uses of Air.

Answer: Uses of air are:

  1. Air is the protective shield that protects the earth from the following impacts:

  • Harmful radiations like UV rays

  • Destruction creating celestial particles like X-rays, cosmic rays, asteroids.

  1. Greenhouse effect: Air contains carbon dioxide that protects the earth from infrared radiation.

  2. Causes changes in weather

  3. Air helps to see the blue sky.

  4. Air helps in pollination.

Question 4: Write Two Atmospheric Properties.

Answer: The two atmospheric properties lie hereunder:


1. Temperature


The temperature of the air is closely linked to the following atmospheric properties:

  • Pressure

Molecules in the air create pressure through both their weight and movement.

  • Volume

  • Density


2. Humidity