AIR AND WATER
The Carbon Cycle
Photosynthesis by plants removes carbon dioxide from the atmosphere
Air
Water
Rust
Nitrogen and Fertilizers
Tests to Identify
Pollution
Purification
Uses
Involves removing solid particles from the water
Chlorination
filtration
water turns white anhydrous copper(II) sulfate blue
Water turns blue anhydrous cobalt(II) chloride pink
In industry, water acts as a solvent and coolant
At home
In power stations(to make steam to turn turbine)
Industries sometimes discharge toxic waste in water bodies
Nitrate fertilizers in water can cause health problems
Greenhouse gases
Pollutants in the Air
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Composition
0.04% carbon dioxide
0.9% carbon dioxide
21%oxygen
Other gases
75% nitrogen
Carbon dioxide
Methane
Causes global warming
Sulfur dioxide and nitrogen oxiders form acid rain and causes breathing difficulties
lead compounds cause brain damage
Carbon monoxide is a poisonous gas
Respiration and combustion of fossil fuels returns carbon to the atmosphere
Plants are either eaten by animals or fossilized over many years and the carbon is transferred
Methods of rust prevention
Coating the metal with paint/oil/plastic
Galvanizing
Sacrificial protection attaching a more reactive metal
Haber process
Temperature- 400degree
Pressure- 200 atm
Iron as catalyst
Fractional distillation of air
The air is passed to fine filters to remove any solids
The air is then cooled to -80C.At this temperature water vapor and carbon dioxide are solids and are removed as they can severe blockages.
the air without the water carbon dioxide is cooled down further to below 200C at which most of the air liquefies
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The liquid air pumped into a fractional column where it is gradually allowed to warm. They turn into gases, which rise and condense in different fractions according to their boiling points.
The gases are collected separately before being stored in tanks and cylinders ready for use.
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Oxides of Nitrogen
Catalytic converters
The following reactions naturally occur to convert toxic pollutants into less toxic ones
but at extremely slow rates: 2CO + O2 --> 2CO2 2NO + 2CO --> N2 + 2CO2
The catalyst in the converter in the exhaust system speeds up these reactions.
Instead of the reactions taking place in the atmosphere at a slow rate the catalytic converter ensures these reactions take place before gases leave the exhaust.
Presence in car engines
The main source of nitrogen oxide is from internal combustion engines. It is NOT the fuel in the engine that creates the oxides, instead the high temperatures generated by the engine that allow the normally unreactive nitrogen and oxygen to react in the atmosphere.
Incomplete combustion
combustions of fossil fuels
Leaded petrols
Requirement for rusting
Iron needs to come in contact with oxygen and water
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Need in fertilizers
plants need nitrogen, potassium and phosphorus in order to grow well, but can’t absorb it as a pure element- it must be a soluble salt (dissolved in water) that the roots can absorb
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Displacement of ammonia
If an ammonium salt is reacted with a strong base, ammonia will be produced along with water and a salt
Example:
NH4Cl(aq) + NaOH(aq) -> NH3(g) + H2O(l) +NaCl(aq)
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Inadequente suply of water
Irrigation
food shortages
famine
Drinking water
Prices for drinking water will begin to increase, causing people to start drinking unpurified water, leading to diseases
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Greenhouse gases
Some gases that mentain the Earth's temperature high enough to support
These gases trap the Sun's electromagnetic radiation
This causes the atmosphere to warm up and leads in global warming
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CO2 is emitted from respiration and combustion
CO2 is absorbed to make carbohydrates in photosynthesis
Animals eat these plants and the carbon consumed is released as CO2 formed during respiration
These animals and plants eventually die and decomposers feed on these dead organisms, the carbon is returned to the atmosphere as CO2