Topic 9- Chemistry of the Atmosphere Flashcards
What are the proportions of the different gases in the atmosphere today?
80% nitrogen
20% oxygen
Small proportions of various other gases i.e CO2, H2O and noble gases
Describe the Earth’s early atmosphere and how it was formed
The Earth was hot when it was formed
There was significant volcanic activity
Gases have been released from these volcanoes
These gases included CO2, N2, CH4, NH3 and H2O
At the start of this period, the atmosphere may have been like atmospheres of Mars and Venus today
How did the amount of oxygen in the atmosphere increase?
Algae and plants produced O2 that is now in the atmosphere by photosynthesis
Algae first produced oxygen about 2.7 billion years ago and soon after this oxygen appeared in the atmosphere
Over the next billion years plants evolved and the % oxygen gradually increased to a level that enabled animals to evolve
How did the amount of carbon dioxide in the atmosphere decrease?
Some CO2 was dissolved in the oceans, where it reacted with metal ions to form insoluble carbonates like CaCO3, or was taken in by animals to become a part of skeleton.
When animal dies, this becomes a sedimentary rock
Some CO2 was used in photosynthesis to make oxygen
What are the advantages of complete combustion?
Less soot (carbon particulates) is made with complete combustion
More heat per gram of fuel is released with complete combustion
Poisonous carbon monoxide is not produced with complete combustion
How is pollution caused by combustion?
When a fuel burns, the gases released to the atmosphere include carbon dioxide, water (vapour), carbon monoxide, sulphur dioxide and oxides of nitrogen
Solid particles and unburned hydrocarbons may also be released that form particulates in the atmosphere
What are the issues regarding sulfur dioxide and oxides of nitrogen?
Sulfur dioxide and oxides of nitrogen cause respiratory problems in humans and cause acid rain.
Acid rain damages plants and buildings
What problems do particulates cause?
Particulates, such as carbon particles, cause global dimming by reducing the amount of sunlight that reaches the Earth’s surface
Particulates cause health problems for humans because of damage to the lungs
