C11 - Air and water Flashcards
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
What two factors does rusting need to work
water and air
what are the different ways to protect metals from corroding
Paint
Grease
Electroplating
In electroplating aluminum is used
to protect the metal from corroding by reacting with oxygen to form a thin layer of aluminum oxide
Coating a metal with zinc is called
galvanizing
A layer of zinc on iron nails helps create
a barrier against water and air and prevents the iron from rusting
Even when there is a scratch when zinc is coated on iron nails it still works because
the zinc corrodes instead of the iron because its more reactive. This is called sacrificial protection
Sulfuric acid is made by
sulfur dioxide + oxygen + water ==> sulfuric acid
SO2 + O2 + H2O ==> 2H2SO4
What gases enter a catalytic converter
CO
unburned hydrocarbons
Oxides of nitrogen
What two ceramic blocks help act as catalysts in a catalytic converter
platinum and rhodium
platinum and palladium
The catalytic converter helps turn
toxic gases into less toxic gases over a hot catalyst
2CO + O2 ==> 2CO2
2NO + 2CO ==> N2 + 2CO2
2NO + N2 + O2
HC (unburned hydrocarbons) + O2 ==> H2O + CO2
The greenhouse effect describes how greenhouse gases (e.g. carbon dioxide and methane) act as
an insulating layer in the atmosphere, re-radiating most of the heat energy which has been reflected off the Earth’s surface back towards Earth.
What are the ways in which CO2 can be released into the athmopshere
Waste product of respiration
Burning of fossil fuels
reactions between acids and metal carbonates
thermal decomposition of metal carbonates
Fertilizers help to
give a plant proper nutrients for it to grow healthy
What elements does a plant need to grow
Nitrogen, Phosphorus and potassium
Why are fertilizers used
Since soil can be depleted of minerals due to crops harvested before taking up the nutrients. Fertilizers help re supply soil with good minerals to help keep plants growth healthy
What are the steps to the haber process
- Collect and purify nitrogen and hydrogen gases
- Pass over iron catalyst at temperature 400 C and atm of 200 (reaction can be reversible)
- Ammonia gas cools in a condenser becoming liquid
Word and symbol equation for haber process
N2 + 3H2 <==> 2NH3
Why can’t plants get nitrogen from the athmosphere
because nitrogen in the air is a double bond meaning it requires a lot of energy to break the bonds
What is the haber process
process in creating ammonia for plants
What does the haber process use
it uses nitrogen from the air and hydrogen which can be obtained from natural gases or cracking
Why does the haber process need 200 atm, 450 C and an Fe catalyst
The temperature allows a faster rate of reaction
The 200 atm allows higher yield of ammonia
The Fe catalyst provides an alternate pathway with a lower activation energy required
What does <==> mean
it is a reversible equation
By condensing the haber process. you can
turn ammonia into a liquid so it can separate
