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IGCSE Chemistry > C11 - Air and water > Flashcards

C11 - Air and water Flashcards

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1
Q

What are the two ways in testing for water

A

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.

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2
Q

What is the importance of water

A

used for coolants and solvents
vital for domestic uses like cooking, cleaning and drinking
Used in industries and homes

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3
Q

Drinking water has to have sufficiently low levels of

A

dissolved salts like sodium chloride

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4
Q

Drinking water cannot have

A

high levels of microbes and bacteria

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5
Q

Potable water is

A

water that is safe to drink

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6
Q

Potable water is different to

A

pure water

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7
Q

Difference between pure and potable water

A

potable water contains dissolved substances but in the low levels while pure water means no dissolved substances at all

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8
Q

Steps to produce potable water

A
  1. Find a good source of fresh water i.e a river
  2. Pass it through a filter to remove materials like leaves and suspended particles
  3. Water is sterilized using chlorine to kill microbes (ozone or ultraviolet can also be used)
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9
Q

What is desalination

A

process which reduces the levels of dissolved minerals to make it into potable water

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10
Q

What are the two ways to carry out desalination

A

distillation or reverse osmosis

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11
Q

Why do we use desalination

A

if there is no good source of fresh water and the only water is the sea

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12
Q

Why is desalination not the best option

A

it requires large amounts of energy making the process extremely expensive

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13
Q

What is the composition of clean air

A

Nitrogen: 78%
oxygen: 21%
Carbon dioxide: 0.04%

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14
Q

What are some common pollutants in the air

A

Carbon monoxide
Sulfur dioxide
Nitrogen oxide

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15
Q

How is carbon monoxide and particulates (soot) formed

A

in the process of incomplete combustion when there isn’t a good supply of O2.

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16
Q

What are the health risks of particulates

A

can cause respiratory problems
create smog
Global dimming

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17
Q

What are the health risks of carbon monoxide

A

Can diffuse into the blood
Bind with hemoglobin in which less O2 gets transported around the body
Cause fainting, comas and death

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18
Q

How is sulfur dioxide formed

A
  1. impurities in hydrocarbons like sulfur atoms are released into the air which bind with O2 to create sulfur dioxide - S + O2 ==> SO2
  2. From volcanoes
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19
Q

How is nitrogen oxide formed

A
  1. In car engines at really high temperatures - N2 + O2 ==> NOx
  2. lightning strikes
20
Q

Problems with sulfur dioxide and nitrogen oxide

A

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

21
Q

What is corrision

A

the process which is the destruction of materials by chemical reactions with substances in the environment

22
Q

Rusting is an example of

A

corrosion

23
Q

Rusting only applies to

A

iron and alloys of iron like steel

24
Q

Metals that aren’t iron go through a process of

A

corroding

25
Q

What two factors does rusting need to work

A

water and air

26
Q

what are the different ways to protect metals from corroding

A

Paint
Grease
Electroplating

27
Q

In electroplating aluminum is used

A

to protect the metal from corroding by reacting with oxygen to form a thin layer of aluminum oxide

28
Q

Coating a metal with zinc is called

A

galvanizing

29
Q

A layer of zinc on iron nails helps create

A

a barrier against water and air and prevents the iron from rusting

30
Q

Even when there is a scratch when zinc is coated on iron nails it still works because

A

the zinc corrodes instead of the iron because its more reactive. This is called sacrificial protection

31
Q

Sulfuric acid is made by

A

sulfur dioxide + oxygen + water ==> sulfuric acid

SO2 + O2 + H2O ==> 2H2SO4

32
Q

What gases enter a catalytic converter

A

CO
unburned hydrocarbons
Oxides of nitrogen

33
Q

What two ceramic blocks help act as catalysts in a catalytic converter

A

platinum and rhodium

platinum and palladium

34
Q

The catalytic converter helps turn

A

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

35
Q

The greenhouse effect describes how greenhouse gases (e.g. carbon dioxide and methane) act as

A

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.

36
Q

What are the ways in which CO2 can be released into the athmopshere

A

Waste product of respiration
Burning of fossil fuels
reactions between acids and metal carbonates
thermal decomposition of metal carbonates

37
Q

Fertilizers help to

A

give a plant proper nutrients for it to grow healthy

38
Q

What elements does a plant need to grow

A

Nitrogen, Phosphorus and potassium

39
Q

Why are fertilizers used

A

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

40
Q

What are the steps to the haber process

A
  1. Collect and purify nitrogen and hydrogen gases
  2. Pass over iron catalyst at temperature 400 C and atm of 200 (reaction can be reversible)
  3. Ammonia gas cools in a condenser becoming liquid
41
Q

Word and symbol equation for haber process

A

N2 + 3H2 <==> 2NH3

42
Q

Why can’t plants get nitrogen from the athmosphere

A

because nitrogen in the air is a double bond meaning it requires a lot of energy to break the bonds

43
Q

What is the haber process

A

process in creating ammonia for plants

44
Q

What does the haber process use

A

it uses nitrogen from the air and hydrogen which can be obtained from natural gases or cracking

45
Q

Why does the haber process need 200 atm, 450 C and an Fe catalyst

A

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

46
Q

What does <==> mean

A

it is a reversible equation

47
Q

By condensing the haber process. you can

A

turn ammonia into a liquid so it can separate

IGCSE Chemistry (16 decks)

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