Download Science Focus 10 Unit 4 Review KEY

Chapter 12 Climate Change and Humans • MHR
ICT OUTCOMES
The Exploring Further item, in combination with the
interview with expert David Phillips, presents an
excellent opportunity for students to satisfy ICT
Outcomes C.5.4.1, C.7.4.1, and F.2.4.7.
UNIT 4 AN ISSUE TO ANALYZE
PROOF OR CONSEQUENCES:
ASSESSING CLIMATE CHANGE
REPORTS
Student Book Pages 476
TR 12-115
Implementing the Investigation
• Explain the investigation to students, highlighting
the perspective of each of the writers using an example.
• Provide students with articles for analysis or allow
students to use various methods (print and electronic
resources) to locate articles. (As an alternative to
print and electronic stories, students could analyze
television or radio news stories.)
• Allow students time to discuss the articles they have
found and choose one to analyze.
• To encourage more meaningful class discussion, have
each group of students analyze an article from a different perspective.
Purpose
• Students find an article on a topic related to climate
change, written from a specific point of view, and
analyze the article and its biases.
Investigation Wrap-up
• Have students answer the Analyze questions based on
their article.
• Discuss Analyze questions in class or collect.
Advance Preparation
Analyze Answers
• Students’ answers will vary. Answers should include
complete references using a standard referencing format. In order to assess students’ responses, you may
wish to use Assessment Rubric 15, Design Your Own
Rubric.
WHEN TO BEGIN
1 week before
WHAT TO DO
• Book computers with Internet access or
search for articles/sources on each
viewpoint for students to use.
APPARATUS
MATERIALS
– computer(s) with Internet
access
– articles on particular
aspects of climate change
presented from a number of
perspectives, or a variety of
resources from which to find
articles
Time Required
• 90 min
- 45 min to search for the articles (individually)
- 45 min to complete the analysis (as a group)
HINTS
&HELPS
• Students may have difficulty finding articles from a variety of
viewpoints. Consider providing a number of articles (one from each
viewpoint) for students to choose from to simplify the investigation.
ASSESSING
STUDENT
INVESTIGATION
Exploring Further, p. 475
ICT OUTCOMES
The Unit Issue to Analyze presents good opportunities
for students to satisfy ICT Outcomes C.2.4.2, C.3.4.1,
C.7.4.1, F.2.4.7, F.3.4.2, F.4.4.1, and F.4.4.3.
UNIT 4 REVIEW ANSWERS
Student Book Pages 478
Understanding Key Concepts
1. The differences between an open, closed, and isolated system are: An open system, such as a biome,
exchanges both matter and energy with its surroundings; a closed system, such as Earth,
LEARNING
CONCEPTS/OUTCOMES
ASSESSMENT OPTIONS
– describe and evaluate the role of science in
furthering the understanding of climate and
climate change through international programs
– describe the role of technology in measuring,
modelling and interpreting climate and climate
change
– use library and electronic research tools to
collect information
– appreciate that scientific understanding evolves
from the interaction of ideas involving people
with different views and backgrounds
– assess students’ class participation and ability
to answer the research questions in the context
of a class discussion
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2.
3.
4.
5.
6.
MHR • Unit 4 Energy Flow in Global Systems
exchanges energy, but not matter with its surroundings; and an isolated system exchanges neither matter nor energy with its surroundings. Some scientists consider the universe itself to be the only truly
isolated system
The biosphere is the place where organisms are
found. Parts of the lithosphere (land), hydrosphere
(water in oceans, rivers, soil, organisms etc.), and
atmosphere (air) also belong to the biosphere.
Earth’s radiation budget is a temperature and energy balance maintained by the fact that Earth reflects
as much energy into space as it absorbs from the
Sun. It is important that Earth “balances” its radiation budget because if the output of energy to space
were greater than the input of energy Earth
receives from the Sun, the temperature on Earth
would drop. Conversely, if the energy output from
Earth were lower than the input of energy from the
Sun, the temperature on Earth would rise. Increases
and decreases in Earth’s average global temperature
would affect climates, and therefore biomes
throughout the world.
The reason the lower atmosphere is warmer than
the upper atmosphere is that visible light from solar
radiation passes through the atmosphere without
heating the atmosphere directly. Solar radiation
reaching Earth’s surface does heat the lithosphere
and hydrosphere, however, which re-radiate the
energy from the Sun as infrared radiation (heat).
Some of this infrared radiation is trapped by greenhouse gases in the atmosphere.
The most common greenhouse gas in the atmosphere is carbon dioxide.
Greenhouse gases have properties that allow them
to absorb the energy of infrared radiation. This
absorbed energy raises the temperature of the air.
When the gases re-radiate the energy, some of it
goes back to the ground.
ASSESSING
STUDENT
INVESTIGATION
Unit 4 An Issue to Analyze:
Proof or Consequences:
Assessing Climate Change
Reports, p. 476–477
7. The characteristics of Earth’s motion responsible
for the changing seasons are that it spins on a tilted
axis as it orbits the Sun. Because of this tilt in
Earth’s axis, the northern hemisphere is leaning
toward the Sun during the summer. From March
through September, the southern hemisphere is
leaning toward the Sun and the solar energy is
more concentrated making it summer in the southern hemisphere when it is winter in the northern
hemisphere.
8. Weather represents the day-to-day temperature and
precipitation, while climate is long-term trends in
temperature and precipitation.
9. The relationship between the Sun’s rays and the
three general climate zones is related to the angle at
which the Sun’s rays hit the Earth and their concentration. In the tropical zone, at some location
throughout the year, the Sun’s rays are perpendicular to Earth’s surface; the Sun’s rays are also concentrated over a smaller area than in the other climate zones, making average temperatures warmer
in the tropical zone than in the other zones. In the
temperate zones in both hemispheres, the Sun’s rays
are never perpendicular to Earth’s surface, and since
they are spread over a larger area, the climate is not
as warm as in the tropical zone. Only 5% of the
Sun’s energy reaches the polar zones (the coldest
zones), since the Sun’s rays make such as small
angle with the Earth in the polar zones that the rays
are distributed over a relatively wide area. At some
times during the year, the polar zones have 24 h of
day light and 24 h of darkness.
10. The specific heat capacity (c) of a substance tells
one how much heat in joules is required to raise the
temperature of 1 g of the substance by 1ºC.
11. The large specific heat capacity of water means that
large bodies of water have a moderating effect on
the climate of a region near the water. It takes a rel-
LEARNING
CONCEPTS/OUTCOMES
– assess, from a variety of perspectives, the risks
and benefits of human activity, and its impact
on the biosphere and the climate
– use library and electronic research tools to
collect information
– select and integrate information from various
sources or from several parts of the same
source
– identify and apply criteria for evaluating
evidence and sources of information, including
identifying bias
– identify multiple perspectives that influence a
science-related decision or issue
– seek and apply evidence when evaluating
alternative approaches to investigations,
problems and issues
ASSESSMENT OPTIONS
– collect and evaluate Analyze answers using
Assessment Rubric 15, Design Your Own
Rubric
– use Assessment Checklist 9, Investigating an
Issue/Controversy
– use Assessment Checklist 24, Using the
Internet
Unit 4 Energy Flow in Global Systems • MHR
12.
13.
14.
15.
16.
17.
18.
atively large amount of heat energy to warm the
water, which can therefore absorb heat from nearby
land, without much change in temperature. During
cold spells, when the water cools it emits heat energy, which warms the nearby land.
Three mechanisms of heat transfer are radiation,
conduction, and convection. Solar radiation warms
Earth’s surface, which re-emits the energy as
infrared radiation. As highly energized molecules
from Earth’s surface collide with molecules in the
air, the heat energy is conducted through the atmosphere. Air currents distribute the heat via convection.
The name for the amount of energy that is needed
to convert 1 mol of a substance from a liquid state
into a gas is the heat of vaporization (Hvap).
Because water has a much larger heat of fusion than
most similar substances, the large amounts of ice
and snow that melt in the spring will not heat up
much, even though the weather is getting warmer.
Most of the available heat energy will go towards
melting the snow and ice.
The amount of water that can remain in the vapour
phase depends on the temperature. When water
vapour in the air rises and cools, the temperature
can go below the dew point - the temperature at
which it begins to condense into liquid water. It is
quite likely that the result will be rain or snow.
The hydrologic cycle is the cycle of water on Earth.
For example, precipitation from the atmosphere
falls onto the land and bodies of water, where it
may freeze, or be absorbed by soil, relocated by
rivers and streams, or taken up by living organisms.
Plants transpire large volumes of water, thereby
returning it to the atmosphere. The hydrologic
cycle transports thermal energy from one place to
another by ocean currents, or when ice and snow
melt, which releases thermal energy to the surroundings.
Ocean currents carry huge amounts of water long
distances around the world. Warm water, such as
the Gulf Stream, can remain warm even after traveling across the Atlantic Ocean and past the British
Isles and toward northern Europe. Since water has
a very large specific heat capacity, it carries a large
amount of thermal energy that can be (and is)
released to the surroundings. The British Isles and
northern Europe are much warmer than they would
be in the absence of the Gulf Stream and the North
Atlantic Drift. Cold ocean currents can have the
opposite effect.
Some deserts are found very close to the coast
because of cool air that is descending, which gets
warmed by compression. Since warmer air can contain more water vapour than cooler air, the percent
humidity goes down. More water can evaporate.
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19. During an El Niño, the prevailing winds reverse
direction over the south pacific. The coast of Peru,
which is normally a desert, experiences heavy rainfalls. Australia and Indonesia become dry. The
widespread change in wind patterns affects the rest
of the world to a lesser degree. The temperature in
central and western Canada is usually warmer.
California might have floods while Ethiopia has a
drought.
20. If Earth was not spinning on its axis, the pattern of
prevailing winds would be simplified: At the equator warm air would rise, move towards the poles
until reaching 30º(N and S), where it would
descend and move back towards the equator.
Similarly convection currents between 30º(N and S)
and 60º(N and S), and between 60º(N and S) and
the poles would also determine the pattern of prevailing winds. Prevailing winds would be to the
north or south.
21. In both hemispheres, the Coriolis effect causes prevailing westerlies between latitudes of 30º and 60º,
and easterlies at other latitudes, because air just
above Earth’s surface rotates at the same speed as
Earth’s surface. Therefore air masses at the equator
travel faster than air masses at 30º latitudes, which
travel faster than air masses at 60º. As a result, air
currents heading from 30º towards the equator continue to rotate more slowly and fall behind the
speed of rotation of Earth’s surface. This creates
westward blowing winds, called easterlies. The
same process occurs between latitudes of 30º and
the poles. Air currents travelling from latitudes of
30º out to 60º retain the greater rotational speed of
Earth’s surface at 30º latitudes, and therefore veer
to the east. Since these winds come from the west
they are called westerlies.
22. Mountains affect climate through orographic precipitation and the rain shadow effect. On the windward side of a mountain range, there will be
increased precipitation caused by adiabatic cooling
while on the leeward side of the mountain, there is
a rain shadow effect (decreased precipitation)
caused by adiabatic warming. These changes in precipitation have an effect on climate.
23. Jets streams are extremely fast moving currents of
air about 10–15 km above Earth’s surface. Jet
streams form at the borders between cold and warm
masses of air, because the colder, denser air pushes
beneath the warmer air, which rises and picks up
speed.
24. A climatograph displays average monthly temperature and total monthly precipitation data for a location.
25. A biome is a large area that experiences a consistent
climate resulting in characteristic plant and animal
species.
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MHR • Unit 4 Energy Flow in Global Systems
26. The subsystems within a biome are the individual
ecosystems, which are each made up of interacting
populations of organisms and their abiotic environment. The location where an organism lives is
called its habitat.
27. Four biomes found in Canada are the tundra, taiga,
deciduous forest, and grassland.
28. With increasing altitude the temperature drops
because warm air moving up a mountainside will
encounter decreasing air pressure; this leads to the
warm air expanding and cooling. As one moves farther away from the equator, the angle at which the
Sun strikes Earth’s surface is smaller, spreading the
same quantity of energy over a larger surface area.
Earth’s surface therefore absorbs less heat energy as
latitude increases. Altitude and latitude also affect
precipitation patterns, but not as predictably as
temperature.
29. Behavioural adaptations that allow animals to stay
warm include migrating to warmer climates during
the winter, shivering, increased activity, huddling
together with others of the same species, sunning
themselves, hibernating, building burrows or shelters, and, in the case of humans, using fires and
machines.
30. Structural adaptations are the physical characteristics organisms have that allow them to survive in
their habitats. Examples will vary, and may include
animal or plant adaptations. For example, cold
weather birds might have feathers on their feet and
legs.
31. A biome is considered an open system because
there is an exchange of both matter (e.g. water and
organisms) and energy (e.g. thermal energy, incoming and reflected solar energy) across its boundaries.
32. There is considerable evidence of climate change
found in fossils, ice core samples, tree rings, and in
erosion and deposition.
33. Catastrophic events such as volcanic eruptions or a
large asteroid or meteorite colliding with Earth
could cause climate change by putting large
amounts of dust and particulates into the atmosphere, creating a sooty, dusty, or smoggy cloud.
The cloud might reflect or absorb solar radiation,
causing temperatures on Earth to drop. However,
this could be followed quickly by warming due to
the build up of greenhouse gases.
34. In a positive feedback loop, the stimulus has an effect
that causes an increase in the original change. For
example, rising global temperatures could lead to a
melting of the polar ice, effectively reducing the
albedo of Earth’s surface, which would in turn cause
temperatures to rise more. In a negative feedback
loop, the stimulus has an effect that “turns off” the
original change; this is how a thermostat operates.
35. A catastrophic event, such as a large volcanic eruption or a large meteorite hitting Earth, injects enormous amounts of dust and soot into the atmosphere, which can spread over much of the world.
Such an event can cause a cooling of the atmosphere by reflecting sunlight back out into space.
Not only is the air cooled, but also plants do not
receive enough light to photosynthesize at a normal
rate. A cool climate and a reduced amount of vegetation can cause a mass extinction because animals
cannot maintain their optimal body temperature
and they cannot find enough to eat.
36. An increased amount of water vapour in the atmosphere will absorb more infrared radiation from
Earth’s surface and thus make the air warmer. The
warmer temperatures cause even more water to
evaporate. As the amount of water vapour builds up
in the atmosphere, it continues to warm by absorbing infrared radiation. The warm temperatures
cause condensation of the vapour and creates heavy
cloud cover. The cloud cover reflects solar energy
back into space and thus begins to cool the atmosphere. The final result was the opposite of the initial change and is thus called “negative” feedback.
37. Students may mention any of the following pieces
of evidence for global warming: Records indicate
that the average global temperature near Earth’s
surface has increased by 0.6ºC in the past century;
the temperature of the lower atmosphere has risen
in the last 40 years; snow and ice cover has melted;
the global average sea level has risen by 0.1–0.2 m.
38. The natural greenhouse effect is caused by carbon
dioxide and water vapour in the air from natural
sources. Those greenhouse gases absorb just
enough infrared radiation to maintain a constant
average global temperature that supports life. With
no greenhouse gases, Earth would be too cold for
life as we know it. The enhanced greenhouse effect
is the addition of excessive amounts of carbon dioxide into the atmosphere by the combustion of fossil
fuels and by the generation of methane in the atmosphere from sources created by humans. Artificial
compounds such as CFCs are also greenhouse
gases. The presence of these additional greenhouse
gases in the atmosphere has the potential to raise
the average global temperature enough to alter climate conditions around the world.
39. The main reason for the increase in the amount of
carbon dioxide in the atmosphere is the advent of
the Industrial Revolution and the increasing rate at
which people are burning fossil fuels.
40. A carbon sink is an area, such as a forest, that
removes and stores large amounts of carbon dioxide
from the atmosphere. Other carbon sinks are deep
oceans, limestone deposits in Earth’s crust, and fossil fuels.
Unit 4 Energy Flow in Global Systems • MHR
41. Saying that “methane has a global warming potential 21 times that of carbon dioxide,” is a way of
saying that methane can trap heat 21 times more
efficiently than can carbon dioxide.
42. Deforestation can affect climate in several ways.
When a forest burns or when organic matter decays
as a result of exposing the forest floor through logging, large amounts of carbon dioxide are released
into the atmosphere. The increase in atmospheric
carbon dioxide could contribute to global warming.
Deforestation may also lead to desertification of an
area. Deforestation also removes the trees that consume carbon dioxide.
43. Some effects of global warming on humans and
other animal species are: Melting of the polar ice
would cause the polar bear’s habitat to shrink,
therefore putting the polar bear at risk; the prairies
could become even drier, which could lead to loss
of arable lands through desertification; and the incidence of dangerously severe weather could increase.
Any reasonable effect — positive or negative — is
acceptable.
44. Climate change could affect a biome because it is
the climate that determines the type of vegetation
that can survive in a biome, and the vegetation and
climate that determines the types of animals that
live in a biome. One biome could be changed into a
different biome.
45. Some ways in which global warming could be
reduced are: decreasing the amount of carbon dioxide in the atmosphere by decreasing the use of fossil
fuels, and by planting forests; decreasing the
amount of methane released to the atmosphere by
changing the diet of beef cattle or burning off
methane released from garbage dumps; decreasing
the amount of dinitrogen monoxide released into
the atmosphere from burning wood and fossil fuels;
banning the use of CFC’s; and, potentially, reducing
photochemical smog.
46. Many glaciers around the world are receding. The
melting in the summer is greater than the accumulation of ice and snow in the winter. These receding
glaciers are a symptom of global warming.
47. The precautionary principle says: “In order to protect the environment, a precautionary approach
shall be widely applied by states according to their
capabilities. Where there are threats of serious or
irreversible damage, lack of full scientific certainty
shall not be used as a reason for postponing costeffective measures to prevent environmental degradation.”
Developing Skills
48. If climate change is gradual, plants will adapt over
time through natural selection. As the temperature
gets warmer and drier, individual species that are
49.
50.
51.
52.
53.
54.
55.
TR 12-119
better able to survive these changes in climate will
survive and produce more offspring with these
traits. Over time, all of the species that survive will
have these traits. If climate change is rapid, there is
no time for natural selection to take place and many
species that are not able to survive the altered conditions will become extinct.
If a room is kept at 18°C in the summer when the
outside temperature is 24°C, the air that enters the
room will not be able to hold as much moisture as
it contained when it was warmer. Water from the
now cooler air will condense on objects in the room
unless it is “dehumidified.” In the winter, the opposite is true. The cold air will have been dried out as
its temperature lowered to –9°C. When that air
enters the warm house and warms up, it will tend to
absorb water from the objects in the house, drying
them unless the air is humidified.
A greenhouse gas is defined as one that traps heat
and keeps it within the atmosphere for a longer
period of time before allowing it to be re-released
into space. Humid places in Canada, such as
Montréal, don’t cool off at night due to the water
vapour in the air, which retains the heat. Dry places
like the Prairies do cool off at night due to the lack
of water vapour in the air. Water vapour, therefore,
classifies as a greenhouse gas.
Climatology is the study of climates today.
Climatology-related careers include hydrology (the
study of water), meteorology (including many subgroups, such as the study of weather), paleoclimatology (the study of past climates), and forecasters
(predicting weather and climate).
Evidence of warming in Canada includes the measurable retreat of glaciers and the thinning of ice in
the Arctic.
Humans have adapted to the places they live by
constructing houses with thick or insulated walls,
small windows, and small doors to keep the heat in
if they live in cold climates. In warm climates, they
build houses that allow a breeze to flow freely. In
areas with significant rain or snowfall, the roofs are
slanted to allow the precipitation to slide off. They
also adjust their clothing to match the climate.
A greenhouse gas delays the solar energy that enters
the atmosphere for a period of time before allowing
it to be released back into space. By absorbing and
radiating the heat, greenhouse gases keep Earth
much warmer than it would be otherwise. Without
the greenhouse effect, the average temperature on
Earth would be much cooler than it is now, and
much of Earth could not sustain life as we know it.
They are both important, but for different reasons.
The natural sources are important in maintaining
Earth at a temperature that sustains life. The
human sources must be carefully monitored as they
MHR • Unit 4 Energy Flow in Global Systems
Problem Solving/Applying
59. Plants and animals from other continents can survive in Alberta because similar temperature and
precipitation patterns (biomes) are found in other
places in the world.
60. The difference is that this climate change is predicted to be occurring at a much more rapid pace
than previous natural climate change. Plants and
animals cannot adapt to changing climate that
quickly.
61. Southern Alberta is predicted to become more like
a desert due to its position in Canada. The entire
world will become warmer. The increase in temperature will lead to increased evaporation resulting in
a drier climate.
62. Circulation of ocean waters is partly a result of different masses of water having different densities.
Salt content and temperature affect the density of
water, therefore, this type of circulation is called
thermohaline circulation. If the density of ocean
water in the North Atlantic were reduced by the
diluting effect of increased rainfall and melting of
the polar ice cap, this would be expected to disrupt
thermohaline circulation. Since thermohaline circulation is partly responsible for bringing warm
waters nearby Northern Europe, a disruption in
this circulation system could mean cooler temperatures in Northern Europe.
63. Scientific inquiry contributes to the decision-making process by providing peer-reviewed ideas
accompanied with a degree of certainty.
64. The precautionary principle is appropriate where
there is a degree of scientific uncertainty accompanied by a considerable risk. The risk of climate
change fits these criteria.
65. By riding a bicycle instead of driving a car, less fossil fuels are burned, which lowers the quantity of
carbon dioxide, dinitrogen monoxide, and ozone
produced.
66. Alberta is home to some of the richest fossil
deposits in the world, including evidence of tropical
plants, suggesting that our climate has changed dramatically over time.
67.
Climatograph
Precipitation (mm)
Temperature (°C)
180
25
160
140
15
120
5
100
-5
80
60
Temperature
(°C)
are the cause of the enhanced greenhouse effect,
which is thought to be leading to climate change.
56. The projected climate change resulting from the
enhanced greenhouse effect is considered a problem
for various reasons: It could potentially alter biomes
and put the species that live there at risk; the pattern of ocean currents could be affected, which
would alter weather patterns and affect aquatic
biomes; it could result in an increase in severe
weather; and it could change farmland into desert.
57. Scientists evaluate the accuracy of computer models
of future climates by using the same model to project into the past. Using data from core samples,
scientists can evaluate how close their modelling
system came to predicting the climate of the past. If
the model was accurate in predicting the past, it has
a better of chance of being accurate in predicting
the future.
58. Burning fossil fuels creates carbon dioxide in the
process of combustion. By cutting down forests,
carbon dioxide is added to the atmosphere in two
ways. The trees that are no longer photosynthesizing do not remove any carbon dioxide from the
atmosphere, and the decomposition of the remaining roots leads to additional carbon dioxide release.
Precipitation
(mm)
TR 12-120
-15
40
-25
20
0
-35
J F M A M J J A S O N D
(a) The warmest month is July.
(b) 11 mm of precipitation falls in the driest month
(August).
(c) The growing season would begin in April (the
first month above 5ºC) and end in October (the
last month above 5ºC).
(d) This location is likely found in a grassland
biome since the total annual precipitation is fairly low (321 mm) and the average temperature is
8.5ºC. To be taiga, the level of precipitation
would have to be significantly higher.
68. Biomes differ from each other with respect to average temperature, overall precipitation, types of animals and plants that inhabit the biome, the distribution of precipitation throughout the year, and the
length of the growing season.
69. Given Mass of air, m = 500 kg = 5.00 × 105 g
J
}
Specific heat capacity of dry air, c = 1.00 }
g•°C
Change of Temperature, DT = 22ºC
Required Heat, Q
Analysis Use Q = mcDT. Solve for Q.
Solution Q = mcDT
J
})(22ºC)
= (5.00 × 105 g)(1.00 }
g•
°C
= 1.10 × 106 J
Paraphrase It takes 1.10 × 106 J of energy to heat
500 kg of dry air by 22 ºC.
Unit 4 Energy Flow in Global Systems • MHR
70. Given Mass of water, m = 35 kg = 3.5 × 104 g
J
}
Specific heat capacity of water, c = 4.19 }
g•°C
6
Heat, Q = 1.4 × 10 J
Required Change of Temperature, DT
Analysis Use Q = mcDT. Solve for DT.
Solution Q = mcDT
c
}
DT = }m
Q
J
})
(3.5 × 104 g)(4.19 }
g•°C
= }}}
6
(1.4 × 10 J)
= 0.10475 ºC
< 0.10ºC
Paraphrase When 1.4 × 106 J of energy are added
to 35 kg of water, the temperature will rise 0.10 ºC.
71. Given Heat, Q = 5.2 MJ = 5.2 × 103 kJ
kJ
}
Heat of fusion of water, Hfus = 6.01 }
mol
g
}
Molar mass of water = 18.02 }
mol
Required Mass of ice (water), m
Analysis Use Q = nHfus. Solve for n..
Solution Q = nHfus
Q
}
n=}
H
fus
5.2 × 103 kJ
= }}
kJ
}
6.01 }
mol
= 865.2246256 mol
m
}
n = }M
m = nM
18.02 g
}
= 865.2246256 mol × }
mol
= 1.5591 × 104 g
< 1.6 × 104 g
Paraphrase If you added 5.2 MJ of energy to some
ice, this would be enough to melt 1.6 × 104 g.
72. Given Mass of water, m = 175 kg = 175 000 g
g
}
Molar mass of water = 18.02 }
mol
Canada. Sceptics will argue that Earth is in a natural
warming phase of this interglacial period, and that
Earth would be warming whether humans were burning fossil fuels or not. Some students may say that the
evidence for human activity leading to an increase in
global warming is more convincing given the correlation between the increase of human-generated greenhouse gases and the increase in temperature over the
last 100 years.
74. Some students may argue that increased temperatures will allow Canadian farmers to grow different
types of crops, and that increased carbon dioxide
levels will promote crop growth. Others will argue
that global warming would probably hurt Canada’s
economy. Although it would be warmer, reducing
our heating costs and making our summers warmer
and more enjoyable, the heat would come at the
price of severe weather and a much drier climate.
The cost of tornadoes, both in dollar values and in
human lives alone, might be too high a price to pay.
Agriculture will be hurt by drought conditions. We
would, in theory, be able to grow more crops with a
longer growing season, but the lack of water and
fairly poor soil might not support these new crops.
75. All of the small plants, shrubs, and animals would
be under water, as would the basements and the
lower part of the first floors of buildings. People
and many of the animals could adapt to this situation by migrating to higher ground. People could
also build structures that would float on the water
or ones that would be above the water (on stilts).
76. Students’ organizers will vary, but may contain
information included in the following web.
H2O(g)
m
}
Number of moles of water, n = }M
m
n = }M}
175 000 g
= }}
g
}
18.02 }
mol
= 9711.431743 mol
kJ
}
Heat of vaporization of water, Hvap = 40.65 }
mol
Required Heat, Q
Analysis Use Q = nHvap. Solve for Q.
Solution Q = nHvap
kJ
})
= (9711.431743 mol)(40.65 }
mol
= 394769.7003 kJ
< 3.95 × 105 kJ
Paraphrase It takes 3.95 × 105 kJ of energy in
order for 175 kg of water at 100ºC to evaporate.
73. Scientists have been tracking an increase in temperature over the last 30 years, which matches with an
increase in greenhouse gas concentration in the
atmosphere. They have also noted glacial melting and
have been tracking the retreat of some glaciers in
TR 12-121
N2O(g)
Respiration
Transpiration
Evaporation
Forest and brush fires
Lightning Fossil fuel combustion
Nitrogen fixation in soil and water
Agriculture Nylon
O3(g)
halocarbons
Smog
Atmosphere
CO2(g)
Forest and brush fires
Respiration Fermentation
Volcanoes Decay
Fossil fuel combustion
(cars, heating, power)
Agriculture Deforestation
Leakage from pipelines
Refrigeration and air conditioning
Solvents
Spray can propellants
Foaming agents
CH4(g)
Deposits in permafrost
and ocean floors
Fermentation in cows and termites
Decomposition in landfills
Ranching
Biomass burning
Rice cultivation
Leakage from pipelines
TR 12-122
MHR • Unit 4 Energy Flow in Global Systems
77. In Alberta, we would suffer severe drought due to
the increase in temperature and changing wind patterns. This would lead to a water shortage. In the
cities, our grass would die as would many other
plants. We would be restricted in how much water
we use to wash and cook, either by rationing or
increasing the cost so people would conserve water.
In rural areas, farming would be hurt by the lack of
water. If irrigation costs became too high, farmers
would abandon their crops, likely leading to desertification and a drastic downturn in the economy.
Critical Thinking
78. If Earth were the size of the Moon, instead of a
three-cell model for air circulation, Earth would
probably have a simple convection current model
where the air would circulate from the equator to
the Poles. The Arctic would be much wetter with
this model. If Earth were twice the size, perhaps it
would follow a six-cell model for air circulation
instead of a three-cell model. This would result in
the Poles being even drier.
79. If global warming occurs to the extent predicted by
the IPCC, many highly populated areas that are
associated with agriculture will experience extensive
drought. If this should happen, water will become a
resource in high demand, as was oil during the late
twentieth century. The present conflict over the
water in the Colorado River is one that will be
waged all over the world.
80. Climate projections into the next century are based
on current data and computer simulations. A simulation must make many educated guesses to predict
climate 100 years into the future. If any of those
guesses are incorrect, the final outcome will be significantly different. The range in predictions
accounts for potentially incorrect guesses. Even
accounting for the inaccuracy of guessing, these
predictions might be completely incorrect if greenhouse gas emissions change significantly from what
is currently projected.
81. Students may argue that a reduction of over 25% is
not realistic given the rate of increase in Canada’s
population, the downturn in the economy, and with
no inexpensive easy-to-implement alternative energy source likely to be available in the near future. If
Canadians are willing to make major changes in
their lifestyle (everyone takes the bus, creates significantly less garbage, uses alternative energy sources
wherever possible), a drastic reduction could be
achieved. The Kyoto Protocol allows for other
mechanisms to “reduce” greenhouse gas emissions,
which may make the target attainable (purchasing
credits from other countries if coupled with some
lifestyle changes.)
82. Students’ responses should note that, while extinctions have occurred naturally in the past, changes in
biomes tended to occur slowly enough that some
species could adapt to the changing conditions.
Rapid changes in environments, such as predicted
global warming trends as a result of human activities, do not give species a long enough period of
time adapt, which could lead to mass extinction.
83. Answers will vary. Some possibilities are: Some
crops are more greenhouse gas-friendly than others
(rice contributes significantly to methane emissions)
and by cultivating these “friendlier” crops, some
emission reductions may be achieved. The methane
that is produced could be effectively trapped with
technology, which allows for cost recouping as the
methane is used as an energy source. Genetically
modified crops that increase crop yields without
more land clearing might be a cost-effective way to
produce food and minimize gaseous emissions.
Wherever possible, land that has been abandoned
should be reforested to restore the soil to its previous fertility and provide carbon dioxide sinks.
84. Albertans may seize the opportunity to help
decrease greenhouse gases if changes do not cost
more to raise cattle. Education programs on how to
raise cattle and sheep without overgrazing the land
(leading to desertification) and on low methaneproducing feed (as long as it is comparable in price)
will provide farmers with the knowledge they need
to help the environment. The government would
be closer to achieving Kyoto targets by reducing
emissions from agriculture, so could offer a tax
break to farmers using low methane-producing feed
(or conversely, increase the taxes on regular feeds).
By educating the public on the amount of energy
used in raising beef, individuals may choose to
change their eating habits to consume less meat.
Although this would, in the short term, decrease
the profits of the ranchers, a growing population
will continue to require beef. New technology that
could trap the methane produced by cattle that
would later be used as an energy source is another
(albeit far-fetched) alternative.
85. Answers will vary but may include the following:
Large boulders can be used to cover the soil and
protect it from the wind; “sand fences” can be used
to keep the sand from spreading; placing straw grids
around an area will decrease the speed of wind, and
vegetation can be planted in this sheltered area; if
irrigation is an option, dunes can be stabilized by
growing shrubs on the windward side, and, after
high speed winds level off the tops of the dunes,
trees can be planted there.
All of these initiatives require some money and
labour. There are also technological issues.
Unit 4 Energy Flow in Global Systems • MHR
Although the building of sand fences is technologically simple, providing irrigation is not.
Environmentally and politically, restoring land is a
positive move as it will help restore economic and
social stability to a nation. The cultural issues
would vary country to country; however, most
countries view efforts to restore and prevent further
destruction to be utmost in importance.
86. Answers will vary, although students should note
that in the twenty-first century, should the IPCC’s
predictions hold true, Alberta will become much
drier and warmer, and other parts of Canada will be
much wetter. In Alberta, skiing and skating may not
be available. We might have to travel to the Yukon
or Northwest Territories to ski. Crop farming may
no longer be possible in Alberta, or, perhaps different types of crop would be grown. Sheep and cattle
ranches may be impossible to sustain, so farmers
may raise desert-adapted livestock, or stop farming
in Alberta. If water is rationed, swimming may also
be a pastime that we will no longer enjoy. Having a
bath may be a luxury that most families will not be
able to afford, and we may take a two-minute showers only once per week.
TR 12-123