In 1774, Joseph Priestly showed that air contains oxygen gas
Composition of Air
- Nitrogen – 78%
- Oxygen – 21%
- Argon – 0.9 %
- Carbon dioxide – 0.01%
- Varying quantities of dust, smoke, water vapour
- During burning of any substance, oxygen is used up and Carbon di oxide is given out
- The amount of water vapour in air varies from place to place and time to time
- Amount of water vapour in air is known as Humidity
- Coastal areas are rich in humidity Ex: Mumbai
- The amount of dust particles in air varies from place to place and time to time
- Dust in air are harmful to our respiratory system
- Fine hair, mucus in nostrils prevent the dust from entering into our respiratory system
- Process of breathing in, getting energy from food and breathing out is called as Respiration
- Humans and most animals breathe in oxygen through Nose and goes into our lungs
- Living things in soil breathe oxygen from soil
- Animals living in water breathe in dissolved oxygen
- Solubility of air reduces as the temperature goes up
- Plants have small openings called Stomata on upper sides of leaves
- Tape grass breathe in oxygen through their body surface
- Nitrogen is required by plants for their growth
- Nitrogen in air is brought to Earth in the form of Nitric acid through Lightening and rain.
- Microorganism in soil convert them into Nitrate compounds which are absorbed by plants
- Nitrogen in air is used to make fertiliser for plants
- Plants use carbon di oxide for preparing its food and gives out oxygen for the entire living organism to the world
- The percentage of oxygen in air remain same even after respiration and burning. This is because of photosynthesis process
- The Natural cycle of consumption of oxygen for respiration and burning and oxygen release by photosynthesis process is called Oxygen cycle
- Oxygen cycle is affected by excessive burning of fossil fuels and deforestation
USES OF AIR:
- Air helps to rotate windmills which in turn generate electricity
- Birds, Insect, aeroplanes, balloons, parachute, fly and work because of air
- Air helps in the dispersal of seeds, pollination and water cycle
- Atmosphere is responsible for weather changes
- Blowing of storms and cyclones are due to the movement of air
- Water vapour in the air is responsible for snowfall and rainfall
- The atmosphere act as a blanket and help Earth’s surface to maintain the right temperature
- The upper atmosphere contains a layer of gas called Ozone
- Ozone filters out the harmful UV rays from the sun that can cause eye problems and skin cancer
Contamination of air by undesirable substances is known as Pollutants
- Main Pollutants of air are Minute dust particles Dust, Smoke
- Harmful gases carbon monoxide, Oxides of sulphur and Nitrogen from fuel in vehicles. Factories, home
- Air pollution can cause number of respiratory problems such as asthma , cough etc.
Methods to control Air Pollution:
- Planting more trees
- Reduce, Reuse and Recycle of waste products
- Use filters in vehicles to prevent harmful gases escaping into the Earth
- Save electricity and reduce burning of fossil fuel
If Unable to download Click here
Useful Links: