Chemistry- Air and water
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- Created by: Kitsune
- Created on: 16-08-16 17:39
What is the composition of air?
78% nitrogen+21% oxygen+ 1% argon, carbon dioxide
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Why isn't air always dry and clean?
It has water vapour and pollutants
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What is the formula for aerobic respiration?
Glucose+oxygen= carbon dioxide + water + energy
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What is air?
A mixture
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How are gases in air separated?
They are cooled to liquid and then separated by fractional distillation
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Why does fractional distillation work?
Because liquids have different boiling points
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Describe steps in fractional distillation of air.
1. air is pumped into plant to remove dust 2. pollutants, water vapour and carbon dioxide are removed by cooling and passing over beads of adsorbent 3.air is compressed, which makes it hot= then it is cooled 4.air passes into large space- cooled more
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Why are the pollutants, water vapour and carbon dioxide removed from fractional distillation?
They would freeze and block the pipes
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At what temperature during fractional distillation are helium and neon removed?
-200 C
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How is air finally separated during fractional distillation?
Liquid air is pumped into fractional column. It is slowly warmed up. Nitrogen boils off first (Lowest boiling point)
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In what order do the gases boil off?
Nitrogen, argon, oxygen, krypton, xenon
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What are the uses of oxygen?
Oxygen masks and tents, coverting impure iron into steel, boxy-acetylene torch
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What are the uses of nitrogen?
Quick freeze food, freeze liquid in cracked pipes, remove oxygen from food packaging
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Where do most pollutants come from?
Burning fossil fuels
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Name the common pollutants.
Carbon monoxide, nitrogen oxides, sulfur dioxide, lead compounds
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Describe CO.
Colourless and odourless
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Describe SO2.
Acidic, sharp smell
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Describe NO and NO2.
Acidic gases
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How is CO formed?
Formed when carbon compounds burn in a limited supply of air
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How is CO dangerous?
Poisonous as haemoglobin can't carry oxygen
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How is SO2 formed?
From burning sulfur compounds in fossil fuels
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How is SO2 dangerous?
Causes acid rain and respiratory problems
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How are NO and NO2 formed?
When nitrogen and oxygen react inside hot car engines
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How are NO and NO2 dangerous?
Causes acid rain and respiratory problems
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How is acid rain dangerous?
It attacks stonework, especially CaCO3, and lowers pH of water, soil, making living organisms die.
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How are lead compounds formed?
From burning lead petrol
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How are lead compounds dangerous?
They damage children's brains Damage kidneys and nervous system in adults.
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How is air pollution reduced?
Flue gas desulfurisation, lead is banned from petrol, catalytic converters in car exhausts
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What is the purpose of a catalytic converter for car exhausts?
To absorb harmful gases onto a catalyst to form harmless gases
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How does a catalytic converter work?
There are two components: A and B. In component A harmful compounds are reduced- 2NO= N2+O2. They flow to component B where oxygen is used to oxidise harmful compounds- 2CO+ O2= 2CO2. Gases flow out of the exhaust pipe.
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How are catalysts placed into catalytic converters?
The are coated on ceramic beads for a large surface area.
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What catalysts are used in catalytic converters?
Transition metals, like platinum
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What is rusting?
The corrosion of iron and steel?
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What steel doesn't rust?
Stainless steel
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What has to be present for rusting to occur?
Water or oxygen
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What are the ways of preventing rusting?
Covering the iron with paint, grease, or another metal (galvanising-used for car bodies) also you can place a more reactive metal like Zn or Mg and let it corrode instead by sacrificial protection
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What are some uses of water?
A solvent in industry, heated to make steam in power stations, for crops and animals on farms, drinking and cooking at home
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What are the two chemical tests for water?
Turns white anhydrous copper sulfate blue. Turns blue copper chloride pink.
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What do river waters contain?
Microbes
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What do microbes in water cause?
Diarrhoea, cholera, typhoid
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How is clean water provided?
A clean water source is found. A coagulant is added to make particles stick together. It passes through flotation tanks-coagulant particles removed. Water passes through sand filter. Chlorination kills microbes. Water is stored in a reservoir
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What can be added to water? For what?
Fluorine to prevent tooth decay.
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Other cards in this set
Card 2
Front
Why isn't air always dry and clean?
Back
It has water vapour and pollutants
Card 3
Front
What is the formula for aerobic respiration?
Back
Card 4
Front
What is air?
Back
Card 5
Front
How are gases in air separated?
Back
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