Research This: Better Lawn Care, page 524
Answers may vary. Sample answers:
A.
The lawn care regulations in my municipality state that certain cosmetic pesticide use is restricted or banned, and the lawn must be satisfactorily maintained.
B.
Two alternatives for urban lawn care are replacing lawn with a naturalized garden or using a push mower.
C.
Replacing Lawn with a Naturalized Garden
Benefits Problems
- minimizes the use of pesticides and herbicides
- preserves the local biodiversity of plants
- reduces the amount of garden maintenance
- may attract wildlife that are beneficial/desired
- may not be typical in your neighbourhood, may not be well received by neighbours
- may attract undesirable wildlife
- will require some maintenance
Using a Push Mower
Benefits
- allows for the grass clippings to decompose into the lawn
- does not release greenhouse gases
- mower requires minimal maintenance
Problems
- can be difficult and/or time consuming to use a push mower if the lawn is very large
- some maintenance is required for the lawnmower
- promotes exercise
D. Imposing a bylaw prohibiting the use of gasoline-powered lawn mowers may not be fair because gasoline-powered mower use is sometimes justified especially for very large areas.
Examples of large areas include large commercial lawns, golf courses, sports fields, and public parks. The bylaw may not always be enforcible since gasoline-powered mower use is widespread. A better plan to reduce air pollution emissions from lawn mowers is through public education. The municipality should encourage citizens to use push mowers and provide
incentives such as rebates to buyers of push mowers.
Section 11.2 Questions, page 525
1.
During flight, compressed air is pumped into the aircraft cabin to ensure a comfortable environment. This is referred to as cabin pressurization. At high altitudes, there are fewer atmospheric gases, which causes the external pressure to be low. If the pressurization fails, the conditions inside the plane will become similar to the external conditions. With less pressure there will be less oxygen present. Oxygen masks are deployed in this situation to ensure passengers and crew have enough oxygen for breathing.
2.
In the troposphere (the layer of the atmosphere closest to Earth) solar energy from the Sun is absorbed by Earth and transferred to air molecules, which increases the temperature of the air.
The temperature in this layer decreases with increasing altitude. In the stratosphere there is an increased concentration of ozone gas. This gas can trap ultraviolet radiation from the Sun causing temperatures to rise in the stratosphere. In this layer, the temperature increases with increasing altitude. The mesosphere contains little ozone and gas concentrations are low, so in this layer the temperature decreases with increasing altitude. The thermosphere contains highenergy gases that absorb solar radiation, so in this layer the temperature increases with increasing altitude.
Copyright © 2011 Nelson Education Ltd. Chapter 11: The Gas State and Gas Laws 11.2-1

3.
Green plants and algae naturally convert carbon dioxide to energy-rich molecules like glucose during photosynthesis. Animals consume molecules like glucose and release carbon dioxide as a waste product of cellular respiration.
4. (a) Radiation from the Sun enters the atmosphere. Much of this radiation is absorbed by
Earth’s surface and is transformed into thermal energy. Warm objects on Earth’s surface emit infrared radiation that is then absorbed by greenhouse gases in the atmosphere. This absorbed radiation is then radiated in all directions, with some exiting the atmosphere into space, some warming the atmosphere, and some returning to Earth’s surface.
(b) Greenhouse gases trap the infrared radiation. These gases re-radiate energy in all directions warming Earth’s surface and the atmosphere.
(c) In the last two hundred years human activity has increased the concentration of greenhouse gases in the atmosphere. This has increased the greenhouse effect.
5.
Answers may vary. Some examples of reducing carbon dioxide emissions are driving less, using public transportation, and carpooling to reduce the use of gasoline; insulating, caulking, and weather stripping to reduce the use of heating fuel; and planting trees that decrease carbon dioxide in the atmosphere to offset daily carbon emissions.
6.
Buying and eating locally grown food might reduce greenhouse gas emissions because local food has not been transported great distances. The amount of carbon dioxide that is released into the atmosphere from transportation is less for local food than food that is not locally produced.
7. (a) Thunder Bay, Ontario is on the shore of Lake Superior. Some scientists predict that water levels of the Great Lakes could decrease due to climate change. This could adversely affect this city, limiting recreation and causing changes to the marine ecosystems.
(b) Iqaluit, Nunavut is in the artic. Climate change is predicted to reduce polar ice. This would result in a loss of habitat for polar bears and many other species. The permafrost in this area could also melt, causing damage to buildings, homes, and roads. Warming could cause sea ice to melt and increase water levels. This could damage shorelines and cause flooding.
(c) Texel, the Netherlands is an island in the North Sea. The North Sea has experienced changes in marine ecosystems due to climate change and overfishing. Decreases in fish stock will also decrease sea bird populations. Changing climate is also expected to change storm patterns and water levels in this region.
(d) Zhengzhou is a city in central China that is located on the Yellow River. Climate change could alter water levels of the river. This could have a significant affect on industries that rely on water. Climate change could also greatly alter the amount of precipitation received in this region.
This region also experiences some tropical storms, and the number and strength of these storms could be altered by climate change.
8.
Answers may vary. Sample answer: Temperature, humidity, and other conditions contribute to the type of crystal formation seen in snowflakes. Paul Shepson and Travis Knepp are studying snow crystals and why transitions in crystal formation occur at different temperatures. The differences in crystal formation are linked to the thin layer of water that often occurs on the surface of snow flakes. This layer will interact with environmental conditions like temperature and humidity, altering snowflake development. According to Shepson’s and Knepp’s research, chemical reactions between the thin water layer on the snow surface can cause the release of chemicals that reduce ground ozone.
Copyright © 2011 Nelson Education Ltd. Chapter 11: The Gas State and Gas Laws 11.2-2

9. (a) Carbon sequestration is the process of removing carbon dioxide and other forms of carbon from the atmosphere and then storing it. Two common types of carbon sequestration are biological and geological.
(b) Answers may vary. Sample answer: Geological carbon sequestration involves injecting carbon dioxide into underground reservoirs. One particular type of geological carbon sequestration is done by injecting carbon dioxide into saline formations. Saline formations are composed of porous rock saturated with salt water. These formations are enclosed by impermeable rock formations. This type of sequestration can hold greater amounts of carbon dioxide and trap it better compared to other methods, and the rock formations required for this type of sequestration are fairly common. More research is required to determine the ability of saline formations to store carbon dioxide over long periods of time.
10.
Answers may vary. Sample answer: Trifluoromethyl sulfur pentafluoride (CF
3
SF
5
) is a recently discovered greenhouse gas. It is one of the most potent greenhouse gases ever discovered–it is 18 000 times better at trapping thermal energy compared to carbon dioxide.
Trifluoromethyl sulfur pentafluoride is stable in our atmosphere, having a lifetime in the range of
1000 years. Research suggests that this gas was not present in the atmosphere prior to the 1960s.
Scientists suspect that this gas is produced by the breakdown of insulating compounds used in high voltage equipment.
11. (a) Answers may vary. Sample answer: The current gasoline price is $1.20 per litre.
(b) The cost in dollars of idling for 10 minutes is:
10 min !
1 h
60 min
!
3.5 L of ga s
1 h
!
$1.20
1 L of ga s
The cost in CO
2
of idling for 10 minutes is:
= $0.70
10 min !
1 h
60 min
!
3.5 L of ga s
1 h
!
2.4 kg of CO
1 L of ga s
2 = 1.4 kg of CO
2
(c) The cost in dollars of idling 10 minutes, 5 times per week, over an entire year is:
$0.70
!
5
1 week
!
52 weeks
1 year
= $182 for 1 year
The cost in CO
2
of idling 10 minutes, 5 times per week, over an entire year is:
1.4 kg !
5
1 week
!
52 weeks
1 year
= 360 kg for 1 year
(d) Answers may vary. Sample answer: The “environmental cost” is more significant than the
“dollar cost.” The “dollar cost” is relatively cheap compared to the cost of driving and maintaining a car. The “environmental cost” accumulates with every person who lets their car idle, creating a significant impact on the environment.
(e) Answers may vary. Sample answer: The carbon dioxide generated by cars in cities can disperse throughout the atmosphere and affect carbon dioxide levels worldwide. Since carbon dioxide can travel throughout the atmosphere, carbon dioxide generated in one location can affect climate in distant locations. One example of this is the increase in carbon dioxide levels in
Antarctica over the last century, where there are no cities.
Copyright © 2011 Nelson Education Ltd. Chapter 11: The Gas State and Gas Laws 11.2-3