Chapter 9, Section 1
Read and discuss section 1: weathering.
Summary
Students conduct a simple experiment to model and explore the harmful effects of acid
rain (vinegar) on living (green leaf and eggshell) and non-living (paper clip) objects.
Engineering Connection
Acid rain is a complex environmental problem that concerns many environmental and
chemical engineers. When engineers examine the acid rain damage to water, wildlife,
forests, crops and structures, they consider the impact on human health. Engineers
design many useful technologies that help industry reduce the amount of harmful
pollutants released into our air. Engineers also help to develop laws that prevent or limit
factories and industries from burning fossil fuels (which release pollutants), or require
them to minimize their pollutant output.
Materials List (I begin requesting glass jars from my students about 2 weeks in
advance)
Each group needs:
1 cup vinegar
1 cup distilled water
2 medium-sized eggshell pieces
2 small green leaves
2 paperclips
2 small- or medium-sized glass jars
masking tape and pen (for labeling containers)
two 1.5-inch strips of wide-range (0-14 pH) litmus paper and pH scale
(page 311 in textbook)
Acid Rain Effects Worksheet, 1 per student (for recording data and
answering questions)
Introduction/Motivation
Acid rain is an environmental problem that concerns many environmental and chemical
engineers. Engineers are always considering the possible effects of acid rain on the
health of humans and the environment when they investigate damage to bodies of
water, wildlife, forests and crops, and contamination of the drinking water supply.
Acid rain is defined as any form of wet precipitation (rain, snow, fog, dew or sleet) that
has a pH less than 5.6 (on a scale of 0 to 14, with 7 being neutral). Large quantities can
also be deposited in a dry form through dust. Acid rain is more acidic than normal rain
and forms through a complex process of chemical reactions involving air pollution and
water molecules in the air. The two most important pollutants that contribute to the
formation of acid rain are nitrogen and sulfur compounds, that primarily come from large
industrial and utility sites. Emissions also come from automobiles and other forms of
transportation, and other industrial processes.
The effects of acid rain may not be immediately apparent. For example, at a glance, a
lake might look clear and beautiful, but a closer look may reveal few living organisms.
Some species of fish cannot survive in water with a pH of less than 5. Clams, snails,
crayfish and other crustaceans, brook trout, walleyed pike and bullfrogs are especially
sensitive to acid in their water supply. Thus, the pH does not have to decrease very
much before fish cannot survive. Insects, birds and mammals are also highly affected
by acid rain. Acid rain can alter soil chemistry, nutrient availability and plant growth. In
their weakened condition, trees and shrubs become vulnerable to insects, diseases and
fungus infestations. For more information, see the Acid Deposition Reading and
Approximate pH of Common Substances References Sheet.
Before the Activity
Practice this activity at home prior to using it in your classroom.
Gather materials and make copies of the Acid Rain Effects Worksheet.
With the Students
1. Divide the class into groups of four students each.
2. Distribute supplies to each group.
3. Ask students to use the pH paper to measure the pH of the vinegar and
the distilled water, and record it on their worksheets.
4. Ask the students to make some predictions. If vinegar contains acid
(acetic acid), then how will the items placed in vinegar change? If these items are
placed in water, will they change in the same ways as in the vinegar?
5. Have students use masking tape and pens to label one jar "vinegar" and
the other one "water."
6. Pour 1 cup of vinegar into the vinegar jar. Place a paperclip, piece of
eggshell and a green leaf in the vinegar. Put the lid on the container.
7. Pour 1 cup of distilled water into the water jar. Place a paperclip, piece of
eggshell and a green leaf in the distilled water. Put the lid on the container.
8. Let the jars sit overnight on a windowsill or protected area.
9. The next day, remove the container lids. Observe any changes in the
condition of the items in the jars. Ask students to write their observations on their
worksheets. (Expected results: In the water containers, the items show no
noticeable changes. In the vinegar jars, the eggshells are soft, the leaf may have
brown spots [this may take a few days], and the paperclip shows no noticeable
changes.)
10. After one week, look for more changes. Make observations again, as often
as you wish.
11. Direct students to complete the questions on their worksheets.
12. Have students compare answers and discuss. Share with class.
*Note: If the students predict that acid rain will not have the same effect to other objects,
try to keep asking them questions to explain their conclusion rather than telling them the
correct answers.
Extension: Have students brainstorm ways to reduce pollutants that cause acid rain.
Working in partners, allow them to research what companies and government are doing
to reduce the problem.
Student example: One way that we can help prevent acid rain is by burning less fossil
fuel. Some types of industries that burn a lot of coal and oil include large power plants,
and paper and wood processing plants. Engineers have helped to develop laws that
prevent or limit large factories and industries from burning fossil fuels or that require
them to minimize their pollutant output. Engineers have also developed many useful
technologies to help industry reduce the harmful pollutants in the air, but the companies
must adhere to the laws and use these technologies. These laws and technologies
include...
Chapter 9, Section 2
Delicious Differential Weathering
Read Section 2 and review vocabulary: weathering, erosion, chemical and physical weathering,
differential weathering
Introduction
This a great activity to review both chemical and physical weathering while eating a Baby Ruth
candy bar. We then compare it to what occurs with the weathering of rock.
Bring a bag of Baby Ruth candy bars to class and instruct students to place a piece of the candy
in their mouths. Instruct the students to suck but not bite the candy. While sucking on the candy,
lecture on the difference between chemical and physical weathering. Have them think about what
is happening in their mouth and how this compares to a rock. Include in this lecture the
difference between weathering and erosion.
After the short lecture the chocolate and caramel should be dissolved and the students are left
with only peanuts. Now give students permission to chew the peanuts, demonstrating
physical/mechanical weathering.
Lead a class discussion as to what type of weathering occurred in the students mouths. How
does this compare to differential weathering of a rock? Show pictures online of rocks that have
experience differential weathering asking students to share their thoughts with their partners.
Ask students the following questions to explain to their partner:
1. What is the difference between chemical and physical weathering?
2. What is the difference between weathering and erosion?
3. What is differential weathering?
Finally, for a quick check, or exit ticket, have the students write a short paragraph explaining the
concept of differential weathering.
Chapter 9 Section 3
Layers of the Soil (Horizons)
After reading Section 3 as a class, go to:
https://www.classzone.com/books/ml_science_share/vis_sim/esm05_pg113_soil/es
m05_pg113_soil.swf to better uderstand soil horizons.
After reviewing the simulation, ask students to
1. Draw a picture of the horizons. (layers of soil)
2. Explain to a friend the horizons and why they are layered in their
respective order.
