C11 - Air and water
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What are the two ways in testing for water
cobalt(II) chloride strips in which the strip will turn from blue to pink and anhydrous copper(II) sulfate turns from colorless to blue in presence of water.
What is the importance of water
used for coolants and solvents vital for domestic uses like cooking, cleaning and drinking Used in industries and homes
Drinking water has to have sufficiently low levels of
dissolved salts like sodium chloride
Drinking water cannot have
high levels of microbes and bacteria
Potable water is
water that is safe to drink
Potable water is different to
pure water
Difference between pure and potable water
potable water contains dissolved substances but in the low levels while pure water means no dissolved substances at all
Steps to produce potable water
• Find a good source of fresh water i.e a river • Pass it through a filter to remove materials like leaves and suspended particles • Water is sterilized using chlorine to kill microbes (ozone or ultraviolet can also be used)
What is desalination
process which reduces the levels of dissolved minerals to make it into potable water
What are the two ways to carry out desalination
distillation or reverse osmosis
Why do we use desalination
if there is no good source of fresh water and the only water is the sea
Why is desalination not the best option
it requires large amounts of energy making the process extremely expensive
What is the composition of clean air
Nitrogen: 78% oxygen: 21% Carbon dioxide: 0.04%
What are some common pollutants in the air
Carbon monoxide Sulfur dioxide Nitrogen oxide
How is carbon monoxide and particulates (soot) formed
in the process of incomplete combustion when there isn’t a good supply of O2.
What are the health risks of particulates
can cause respiratory problems create smog Global dimming
What are the health risks of carbon monoxide
Can diffuse into the blood Bind with hemoglobin in which less O2 gets transported around the body Cause fainting, comas and death
How is sulfur dioxide formed
• impurities in hydrocarbons like sulfur atoms are released into the air which bind with O2 to create sulfur dioxide - S + O2 ==> SO2 • From volcanoes
How is nitrogen oxide formed
• In car engines at really high temperatures - N2 + O2 ==> NOx • lightning strikes
Problems with sulfur dioxide and nitrogen oxide
Can cause respiratory problems in the lung Can mix in the clouds to form dilute sulfuric acid and dilute nitric acid which turns into acid rain. Acid rain can corrode metals and damage buildings and statue made from limestone. Can also damage plants and make soil acidic
What is corrision
the process which is the destruction of materials by chemical reactions with substances in the environment
Rusting is an example of
corrosion
Rusting only applies to
iron and alloys of iron like steel
Metals that aren’t iron go through a process of
corroding