C11 water and air Flashcards
Eutrophication
The nitrates from excessive use of fertilizers get into water. This causes the growth of algae that eventually die and decay. The bacteria responsible for this decay use up the oxygen in the water causing the amount of dissolved oxygen to decrease and kill animal life
Aqueous solution
A solid dissolved in water
Solvent
Liquid that dissolves solids. Water is the most common solvent and is excellent at dissolving ionic substances. Non aqueous solvents are good at dissolving molecular solids such as oil and grease
Soluble/insoluble
If a solid is able to dissolve of not in a particular solvent
Fractional distillation
A process by which components in a chemical mixture are separated according to their different boiling points. Vapors from a boiling solution are passed along a column. The temperature of the column gradually decreases along its length. Components with higher boiling points condense on the column and return to the solution; components with a lower boiling points pass through the column and are collected
Rusting
The formation of reddish brown ferric oxides on iron by low temperature oxidation, in the presence of water and air
Ammonia
Alkaline has made in the Haber process from nitrogen and hydrogen
Ammonium salts
Ammonium nitrate, sulfate or chloride. Made by neutralizing ammonia with a particular acid. Very soluble and useful as a chemical fertilizer.
Fertilizer
Compounds that contain vital elements requires for healthy growth of plants. These mainly include the elements nitrogen, phosphorous and potassium (NPK)
Litmus paper
Used as a test for the alkaline nature of ammonia gas. Damp red litmus will turn blue
Leaching
High solubility of chemical fertilizers in water means that they may be washed from the land into local streams and rivers causing massive environmental impact (eutrophication). Can be reduced by using less fertilizer and by not using before heavy rain
Haber process
A reversible reaction where nitrogen and hydrogen react to give ammonia. Process is favored by high pressure and low temperatures with an iron catalyst
Chlorination
The process by which chlorine is added to drinking water to kill the bacteria
Sacrificial protection
By attaching a more reactive metal to iron, for example zinc, the zinc will corrode in preference to the iron. As a result the iron does not rust. Ships have zinc blocks attached to them and are periodically replaced
Conditions required for iron to rust
Oxygen and water must be present. Salt also helps to speed up the rusting
How do oil, greasing and painting prevent rust forming? What are the disadvantages to this method?
It forms a barrier to prevent the iron from being exposed to the air and moisture.
The barrier could be scratched/ damaged, and the rusting will start
Galvanising
to coat iron or steel with a protective layer of zinc to form a zinc oxide. This prevents the zinc from corroding and the iron from rusting
Difference between galvanising and sacrificial protection
Galvanising: only occurs with zinc. Must coat all of the iron
Sacrificial protection: Can be used with any metal more reactive than iron. Does not need to cover all of the iron
The composition of clean air
a mixture of 78% nitrogen, 21% oxygen, and small quantities of noble gases, water vapor and carbon dioxide
Common air pollutants
Carbon monoxide, sulfur dioxide, oxides of nitrogen
Tests for water (there’s 2)
1) add anhydrous copper II sulphate to water. It should turn from white to blue
2) Dip in a piece of dry blue cobalt chloride paper. It should turn from blue to pink
causes of carbon monoxide
Burning of fuels (300 million tonnes per year) Forest fires, biological processes (3000 million per year)
causes of sulphur dioxide
burning of coal, oil, and roasting of sulphide ores (146 million a year) Volcanoes (9 million per year)
causes of hydrocarbons
vehicle exhausts, chemical processes (88 million per year) Biological processes (1000 million per year)
causes of nitrogen oxides
Vehicle exhausts, burning of fuels (50 million per year) Bacterial action in soils, electrical storms (160 million per year)
causes of ammonia
Waste treatment (4 million per year) Biological decay (150 million per year)
causes of hydrogen sulphide
Chemical processes, sewage treatment (3 million per year) Volcanoes and biological decay (65 million per year)
Fractional distillation of liquefied air
1) the air is turned into a mixture of liquids. This is done by cooling air so that water can freeze and be removed
2) The remaining air is cooled to -200 degrees celsius where it is liquefied
3) Liquid air is warmed up to -185 degrees celsius in the fractionating column - causes all nitrogen to evaporate and rise up the column
4) Liquid oxygen is piped out at the bottom
Freezing point of carbon dioxide
-79 degrees celsius
Boiling point of oxygen
-183 degrees celsius
Boiling point of Nitrogen
-196 degrees celsius
Boiling point of argon
-186 degrees celsius
How is water purified?
1) goes through a screen- traps any large particles such as twigs
2) a coagulant is added- a chemical to make all the small suspended particles stick together
3) air is blown through the water in flotation tanks, to make the coagulated particles float to the top and be skimmed off
4) Water passed through a bed of sand to filter it. It may go through further filters, e.g charcoal to remove bad tastes /smells
5) Chlorine added to kill bacteria. Fluorine can be added to help fight tooth decay
6) Water pumped into a storage reservoir
