Air Flashcards
1
Q
What does the atmosphere surrounding the earth contain?
A
“The atmosphere surrounding the earth contains air. “
2
Q
What is air mainly composed of?
A
“Air is a mixture of gases
3
Q
What are the main components of air by volume?
A
“Nitrogen (78%)
4
Q
How can the constituents of air be separated?
A
“The constituents of air can be separated easily by physical methods. “
5
Q
Describe the process of liquefying air.
A
“If highly compressed air is allowed to escape through a minute aperture
6
Q
How are pure nitrogen and oxygen separated from liquid air?
A
“Pure nitrogen and oxygen can then be separated out at different temperatures by fractionally distilling the liquid air. “
7
Q
Do the constituents of air retain their individual properties?
A
“The constituents of air still retain their individual properties. “
8
Q
What happens when air is passed through caustic soda?
A
“The carbon(IV) oxide in the air is absorbed by the caustic soda. “
9
Q
What happens when air is passed through lime water?
A
“The carbon(IV) oxide is absorbed and the lime water turns chalky. “
10
Q
What property does oxygen retain?
A
“The oxygen retains its oxidizing property. “
11
Q
What happens when air is passed over heated copper?
A
“The copper becomes oxidized by the oxygen in the air to form copper(II) oxide. “
12
Q
What property do nitrogen and rare gases retain?
A
“The nitrogen and the rare gases retain their inertness. “
13
Q
What happens when the constituents of air are mixed together?
A
“If the appropriate proportions of each of the different constituents of air are mixed together under ordinary conditions
14
Q
Can the composition of air be represented by a chemical formula?
A
“The composition of air cannot be represented by a chemical formula as in the case of a compound. “
15
Q
Does the composition of air vary?
A
“The exact composition of air varies from place to place. “
16
Q
What is the most active constituent of air and what percentage does it make up?
A
“Although oxygen makes up only one-fifth by volume of air
17
Q
What is oxygen necessary for?
A
“It is necessary for cellular respiration in all living organisms
18
Q
What is burning or combustion?
A
“Most substances burn in air. Burning or combustion is a chemical reaction which is frequently accompanied by the production of light and heat. “
19
Q
What happens during combustion?
A
“During this reaction
20
Q
What are the products of candle wax combustion?
A
“When candle wax
21
Q
What may be produced when the supply of air is limited during combustion?
A
“When the supply of air is very limited
22
Q
What are flames?
A
“Flames are produced when substances burn. A flame can be described as a region where gases combine chemically
23
Q
Is oxygen always necessary for combustion?
A
“In most cases
24
Q
Are flames homogeneous?
A
“Flames are not homogeneous
25
What does the type of flame produced depend on?
"The type of flame produced depends on the nature of the substance that is burning. "
26
What are the two types of flames?
"A flame may be luminous or non-luminous. "
27
What causes the luminosity of a flame?
"The luminosity of a flame is caused by the presence of solid particles in the flame. "
28
What increases the luminosity of a flame?
"An increase in the temperature or pressure of the burning gases also increases the luminosity of a flame. "
29
Describe a hydrogen flame.
"Hydrogen burns with a very fair non-luminous flame. The structure of the hydrogen flame is simple
30
Describe a candle flame.
"A candle burns with a luminous flame. Four zones can be identified in the flame: the zone of unburnt gas around the wick; the bright yellow luminous zone where there is incomplete burning of the hydrocarbon due to insufficient air supply - the luminosity is caused by the presence of unburnt carbon particles; the barely visible
31
What is a Bunsen burner?
"A Bunsen burner is built with an air inlet at the base of the burner tube so that a stream of air can be supplied to the flame together with the fuel gas. This supplements the external supply of air
32
What is the fuel for a Bunsen burner?
"The fuel for the Bunsen burner is a mixture of hydrocarbon gases (methane and butane) and some hydrogen and carbon(II) oxide. "
33
What are the products of Bunsen burner combustion?
"The products of combustion are mainly water
34
How is a luminous Bunsen flame produced?
"To produce a luminous Bunsen flame
35
How is a non-luminous Bunsen flame produced?
"To produce a non-luminous Bunsen flame
36
What is striking-back in a Bunsen burner?
"If the air-hole of a Bunsen burner is opened too widely or the fuel supply is slowly turned down
37
What is the result of metal corrosion?
"The corrosion of metals results from the combined action of atmospheric oxygen and water. "
38
What accelerates metal corrosion?
"It is accelerated by the presence of carbon (IV) oxide and gaseous pollutants like sulphur (IV) oxide in the air. "
39
Give an example of common metallic corrosion.
"The corrosion of iron is common. The most important example of metallic corrosion is that of iron. "
40
What is the chemical name for iron rust?
"Iron rusts by combining with oxygen in the presence of water to form brown hydrated iron(III) oxide (commonly known as rust)
41
Describe the properties of rust.
"Rust is soft and breaks off easily. When this happens
42
What are the methods to prevent rusting?
"Some of the methods used to prevent or reduce rusting are: 1. Alloying the iron with other metals. 2. Coating the iron surface with a non-corrosive metal. 3. Coating the iron surface with paint. 4. Coating the iron surface with oil or grease. "
43
Explain alloying to prevent rusting.
"Alloying is the process of mixing iron with other metals such as chromium and nickel to produce stainless steel which does not rust. "
44
Explain coating with non-corrosive metal to prevent rusting.
"Coating the iron surface with a non-corrosive metal such as tin or zinc prevents oxygen and moisture from coming into contact with the iron surface. Tin is used for coating food cans while zinc is used for galvanizing iron sheets. "
45
Explain coating with paint to prevent rusting.
"If the iron surface is coated with paint
46
Explain coating with oil or grease to prevent rusting.
"Coating the iron surface with oil or grease also keeps out oxygen and moisture. This method is suitable for moving parts of machinery. "
47
What are the main air pollutants?
"Some of the main air pollutants are smoke
48
What is smoke and its effects?
"Smoke consists of very fine solid and liquid particles (mainly carbon) suspended in air. It is produced whenever there is incomplete combustion of fuels such as wood
49
What are the sources of carbon(II) oxide pollution?
"Carbon(II) oxide is produced when carbon-containing fuels such as coal
50
What are the harmful effects of carbon(II) oxide?
"It is very poisonous because it combines with the haemoglobin in the blood
51
What are the sources of sulphur(IV) oxide pollution?
"Sulphur(IV) oxide is produced when sulphur and sulphur-containing compounds such as petroleum burn in air. It is also released during the extraction of metals from sulphide ores. "
52
What are the harmful effects of sulphur(IV) oxide?
"It is a colourless gas with a pungent irritating smell. It causes respiratory problems. In the atmosphere
53
What are the sources of oxides of nitrogen pollution?
"Oxides of nitrogen are formed when atmospheric nitrogen and oxygen combine during thunderstorms and in internal combustion engines. "
54
What are the harmful effects of oxides of nitrogen?
"They are poisonous gases which cause respiratory problems. They also contribute to acid rain and the formation of smog. "
55
What is smog?
"Smog is a mixture of smoke
56
What are the effects of lead compounds as pollutants?
"Lead compounds from motor vehicle exhaust are poisonous and can cause brain damage
57
What are the effects of fluorine compounds as pollutants?
"Fluorine compounds from the manufacture of aluminium and fertilizers can cause bone and teeth diseases in animals. "
58
What are the effects of chlorofluorocarbons (CFCs) as pollutants?
"Chlorofluorocarbons or CFCs are a group of man-made compounds used in refrigerators
59
What is the ozone layer and its importance?
"The ozone layer is found in the stratosphere. It is important because it acts as a shield preventing too much ultra-violet light from reaching the earth's surface. "
60
What are the effects of a diminishing ozone layer?
"A diminishing ozone layer means an increase in the level of ultra-violet radiation that reaches earth. This poses a danger to human health and may cause an increase in cataracts
61
What are some methods of controlling air pollution?
"Some methods of controlling air pollution are as follows: 1. Strict laws should be passed to make factories and users of motor-vehicles keep air pollution down by using anti-pollution devices and taking anti-pollution measures. 2. Machinery should be improved so that more efficient fuel combustion occurs. 3. People should be educated to make them aware of the causes and dangers of pollution. "
62
What are compounds that deplete the ozone layer?
"Chlorofluorocarbons or CFCs are a group of man-made compounds used in refrigerators
63
What is the function of the ozone layer?
"The ozone layer is Question
64
What is the composition of air?
"Air is a mixture of gases
65
What are the percentages of the main components of air?
"Nitrogen (78%)
66
Can air be separated into its constituents by physical methods?
"Yes"
67
Describe the process of liquefying air
"Highly compressed air expands through an aperture
68
How are nitrogen and oxygen separated from liquid air?
"By fractional distillation at different temperatures."
69
Do the constituents of air retain their properties?
"Yes"
70
What happens when air is passed through caustic soda?
"Carbon(IV) oxide is absorbed."
71
What happens when air is passed through lime water?
"Carbon(IV) oxide is absorbed
72
What property does oxygen retain?
"Oxidizing property."
73
What happens when air is passed over heated copper?
"Copper is oxidized to copper(II) oxide."
74
What property do nitrogen and rare gases retain?
"Inertness."
75
What happens when the constituents of air are mixed?
"They form a mixture resembling ordinary air without chemical combination."
76
Can the composition of air be represented by a chemical formula?
"No"
77
Does the composition of air vary?
"Yes"
78
What is the most active constituent of air?
"Oxygen"
79
What percentage of air is oxygen?
"21%"
80
What is oxygen necessary for?
"Cellular respiration
81
What is burning or combustion?
"A chemical reaction with heat and light."
82
What happens during combustion?
"Combustible material combines with oxygen to form oxides."
83
What are the products of candle wax combustion?
"Water and carbon(IV) oxide."
84
What may be produced during incomplete combustion?
"Carbon(II) oxide or soot."
85
What are flames?
"Regions where gases combine chemically
86
Is oxygen always necessary for combustion?
"No"
87
Are flames homogeneous?
"No"
88
What does the type of flame depend on?
"The nature of the burning substance."
89
What are the two types of flames?
"Luminous and non-luminous."
90
What causes the luminosity of a flame?
"Solid particles in the flame."
91
What increases flame luminosity?
"Increased temperature or pressure."
92
Describe a hydrogen flame.
"Non-luminous with two zones: unburnt gas and complete combustion."
93
Describe a candle flame.
"Luminous with four zones: unburnt gas
94
What is a Bunsen burner?
"A burner with an air inlet for more complete combustion."
95
What is the fuel for a Bunsen burner?
"Hydrocarbon gases (methane and butane)
96
What are the products of Bunsen burner combustion?
"Water
97
How is a luminous Bunsen flame produced?
"With a closed air-hole
98
How is a non-luminous Bunsen flame produced?
"With an open air-hole
99
What is striking-back in a Bunsen burner?
"Flame entering the tube due to too much air or low fuel
100
What is the result of metal corrosion?
"Combined action of oxygen and water."
101
What accelerates metal corrosion?
"Carbon (IV) oxide and gaseous pollutants."
102
Give an example of common metallic corrosion.
"Rusting of iron."
103
What is the chemical name for iron rust?
"Hydrated iron(III) oxide ($Fe_{2}O_{3}xH_{2}O$)"
104
Describe the properties of rust.
"Soft
105
What are the methods to prevent rusting?
"Alloying
106
Explain alloying to prevent rusting.
"Mixing iron with metals like chromium and nickel to make stainless steel."
107
Explain coating with non-corrosive metal to prevent rusting.
"Using tin (for cans) or zinc (for galvanizing) to prevent contact with oxygen and moisture."
108
Explain coating with paint to prevent rusting.
"Paint keeps out oxygen and moisture."
109
Explain coating with oil or grease to prevent rusting.
"Suitable for moving parts to keep out oxygen and moisture."
110
What are the main air pollutants?
"Smoke
111
What is smoke and its effects?
"Fine particles causing respiratory issues and reduced visibility."
112
What are the sources of carbon(II) oxide pollution?
"Incomplete combustion of fuels
113
What are the harmful effects of carbon(II) oxide?
"Poisonous
114
What are the sources of sulphur(IV) oxide pollution?
"Burning sulphur-containing compounds and extracting metals from sulphide ores."
115
What are the harmful effects of sulphur(IV) oxide?
"Respiratory problems
116
What are the sources of oxides of nitrogen pollution?
"Thunderstorms and internal combustion engines."
117
What are the harmful effects of oxides of nitrogen?
"Poisonous
118
What is smog?
"Mixture of smoke
119
What are the effects of lead compounds as pollutants?
"Poisonous
120
What are the effects of fluorine compounds as pollutants?
"Cause bone and teeth diseases in animals."
121
What are the effects of chlorofluorocarbons (CFCs) as pollutants?
"Damage the ozone layer."
122
What is the ozone layer and its importance?
"Stratospheric layer that shields Earth from UV light."
123
What are the effects of a diminishing ozone layer?
"Increased UV radiation
124
What are some methods of controlling air pollution?
"Laws
125
found in the stratosphere. It is important because it acts as a shield preventing too much ultra-violet light from reaching the earth's surface."
126
What are the effects of the depletion of the ozone layer?
"A diminishing ozone layer means an increase in the level of ultra-violet radiation that reaches earth. This poses a danger to human health and may cause an increase in cataracts
127
What are the methods for controlling air pollution?
"Some methods of controlling air pollution are: 1. Strict laws for factories and motor-vehicle users to reduce pollution. 2. Improving machinery for more efficient fuel combustion. 3. Educating people about pollution causes and dangers."
128
What is the composition of air?
"Air is a mixture of gases
129
What are the approximate percentages of the main gases in air?
"Nitrogen is about 78%
130
Can air be separated into its components by physical methods?
"Yes."
131
Describe how air can be liquefied.
"Highly compressed air is allowed to expand rapidly
132
How are pure nitrogen and oxygen obtained from liquid air?
"By fractional distillation at different temperatures."
133
Do the gases in air retain their individual properties?
"Yes."
134
What happens when air is passed through caustic soda solution?
"The carbon(IV) oxide is absorbed."
135
What happens when air is passed through lime water?
"The carbon(IV) oxide is absorbed
136
What property of oxygen is retained in air?
"Its oxidizing property."
137
What happens when air is passed over heated copper?
"The copper is oxidized to copper(II) oxide."
138
What property do nitrogen and noble gases retain?
"Their inertness."
139
When the constituents of air are mixed, do they chemically combine?
"No
140
Can air's composition be represented by a chemical formula?
"No."
141
Does the composition of air vary from place to place?
"Yes."
142
Which gas is the most active component of air?
"Oxygen."
143
What percentage of air is oxygen by volume?
"About 21%."
144
What is oxygen essential for?
"Cellular respiration
145
Define burning or combustion.
"A chemical reaction
146
What happens during combustion?
"A substance combines with oxygen to form oxides."
147
What are the products of candle wax combustion?
"Water and carbon(IV) oxide."
148
What may be produced if combustion is incomplete?
"Carbon(II) oxide or soot (carbon particles)."
149
What are flames?
"Regions where gases chemically combine
150
Is oxygen always necessary for combustion?
"No."
151
Are flames homogeneous?
"No."
152
What does the type of flame depend on?
"The substance burning."
153
What are the two main types of flames?
"Luminous and non-luminous."
154
What causes a flame to be luminous?
"Solid particles in the flame."
155
What increases the luminosity of a flame?
"Higher temperature or pressure."
156
Describe a hydrogen flame.
"It's non-luminous with two zones."
157
Describe a candle flame's structure.
"It has four zones: unburnt gas
158
What is a Bunsen burner?
"A burner with an air inlet for better combustion."
159
What is the fuel used for a Bunsen burner?
"Hydrocarbon gases (methane and butane) and some hydrogen and carbon(II) oxide."
160
What are the products of Bunsen burner combustion?
"Mainly water
161
How is a luminous Bunsen flame produced?
"By closing the air-hole; it's tall
162
How is a non-luminous Bunsen flame produced?
"By opening the air-hole; it's hotter and cleaner."
163
What is 'striking-back' in a Bunsen burner?
"When the flame enters the burner tube; correct by adjusting the air-hole."
164
What causes metal corrosion?
"Oxygen and water."
165
What accelerates metal corrosion?
"Carbon(IV) oxide and pollutants."
166
Give an example of common metallic corrosion.
"Rusting of iron."
167
What is the chemical name for iron rust?
"Hydrated iron(III) oxide."
168
Describe the properties of rust.
"It's soft
169
List methods to prevent rusting.
"Alloying
170
Explain how alloying prevents rusting.
"Mixing iron with other metals to form stainless steel."
171
Explain how coating with non-corrosive metals prevents rusting.
"Using tin or zinc to block oxygen and moisture."
172
Explain how coating with paint prevents rusting.
"Paint keeps out oxygen and moisture."
173
Explain how coating with oil or grease prevents rusting.
"It's suitable for moving parts to keep out oxygen and moisture."
174
Name some main air pollutants.
"Smoke
175
What is smoke and its effects?
"Fine particles that cause respiratory problems and reduce visibility."
176
What are the sources of carbon(II) oxide pollution?
"Incomplete combustion of fuels
177
What are the harmful effects of carbon(II) oxide?
"It's poisonous
178
What are the sources of sulphur(IV) oxide pollution?
"Burning sulphur compounds and extracting metals from sulphide ores."
179
What are the harmful effects of sulphur(IV) oxide?
"Causes respiratory problems and forms acid rain."
180
What are the sources of nitrogen oxides pollution?
"Thunderstorms and internal combustion engines."
181
What are the harmful effects of nitrogen oxides?
"Poisonous
182
What is smog?
"A mixture of smoke
183
What are the effects of lead compounds as pollutants?
"Cause brain damage."
184
What are the effects of fluorine compounds as pollutants?
"Cause bone and teeth diseases in animals."
185
What are the effects of chlorofluorocarbons (CFCs) as pollutants?
"Damage the ozone layer."
186
What is the ozone layer's function?
"It shields Earth from excessive UV light."
187
What are the effects of ozone layer depletion?
"Increased UV radiation
188
What are methods to control air pollution?
"Laws
