Unit C
Environmental
Chemistry
reference
p 183 - 190 Science in Action 9
What is Environmental
Chemistry
• Environmental Chemistry Summary
• Should you trust Chemists or Cows?
UNIT C
ENVIRONMENTAL CHEMISTRY
Section 1.1 Chemicals in the Environment
• All living things are made of chemicals and
depend upon chemistry for survival.
• Some chemicals that are produced either
naturally or by humans can be harmful to the
living and non-living environment.
• Elements such as carbon and oxygen are
constantly moving throughout the ecosystem in
a cyclic pattern as they form chemical
compounds that are used by living things.
• Water is a compound that cycles through the
environment.
The Nitrogen Cycle
• Nitrogen is an important element since
it is required by plants to make
substances necessary to life.
The concentration of useable nitrogen can be
added or taken away from the soil in several
ways:
• Nitrated are added by:
1. nitrogen fixing plants
2.fertilizers/compost/manure
3. lightning
• Nitrates are taken away by:
1. bacteria that convert soil nitrates into free
N2
2. water carries away nitrates
3. harvesting plants
More on nitrogen fixation
• Nitrogen fixing plants like legumes
(clover, alfalfa, beans) contain bacteria in
their root nodules
• These bacteria convert free nitrogen (N2)
in the air into nitrates that can be used
by plants, so they fertilize the soil!
• Nitrogen and Phosphorus cycles
Processes and Activities that Affect
Environmental Chemicals
A. Natural Processes:
• Chemical Cycles – cycling of elements
and compounds through the
environment, like the nitrogen cycle
• Cellular respiration – food chemicals
and oxygen are used to provide the
body with energy, carbon dioxide is
produced
B. Human Activities:
1. Pollution – any change in the environment
that produces conditions harmful to living
things, such as smog and forest fires
There are many kinds of
pollution
• Noise
• Thermal (Lake Wabamun)
• Chemical
2. Agricultural Activities – farmers use
chemicals to help control the growth of
their crops.
a) Fertilizers - chemicals added to the soil
to increase plant growth.
- usually contain nitrogen, phosphorus and
potassium, three elements essential for
plant growth. Sometimes sulfur is
added.
10 % K
Fertilizers are labeled with a
number that indicates the
percentage of nitrogen,
phosphorus and potassium
Different ratios are used to
achieve different goals
Eg. Root growth, or leaf
growth
problem: too much can harm the crop
b) Crop rotation
Crops that are
nitrogen fixing
increase soil
nitrates
eg. clover,
alfalfa and
peas
c) Pesticides - chemicals used to kill
pests (organisms that harm people,
crops or structures).
- grouped by what they kill: herbicides
kill weeds,
insecticides kill insects, fungicides kill
fungus
Problems:
1. some are not selective and kill both pests
and non-pests (Round-up)
2. some remain in the environment and can be
passed on to other organisms
3. pests can become resistant to them
Organic Foods- are grown in an
environment free of pesticides
PESKY PESTICIDES
• an estimated 20,000 cancer deaths each year in
the U.S. are caused by pesticide residues on
food
• an estimated 3.5 million cases of acute
pesticide poisoning are caused each year in
developing nations due to lack of protection
during pesticide application
• an estimated 900 plant and insect species have
built up resistances to pesticides
• 4.1 billion pounds of pesticides are used
throughout the world each year
• 30 times more pesticides are used today
than were used in 1945
• 30 percent of insecticides are believed to
be carcinogenic
• 60 percent of herbicides are believed to
cause cancer
• 90 percent of fungicides are believed to be
carcinogenic (cause cancer )
• 23 of the 28 most commonly used
pesticides are believed to be carcinogenic
3. Solid Wastes – garbage from homes
and industry that cannot be recycled is
put into landfills which are specially
constructed with plastic liners and
compacted clay to prevent chemicals
leaking into the ground (leaching).
Some solid waste is incinerated or burned
at high temperatures and some of the
gases released contribute to air
pollution.
4. Wastewater or Sewage – water containing
dissolved and undissolved materials, called sewage,
is carried by pipes into a septic tank in rural areas
and to water treatment plants in the city.
Septic tank – underground container where
bacteria break down organic materials before they
are moved out into the soil
Sewage treatment plant – treats
wastewater from homes and industry and releases
it (now called effluent) into rivers and lakes.
Effluent often contains nitrogen and phosphorus.
Storm sewers – large areas used to
collect street water before it is
released into rivers and lakes. This
water contains chemicals washed off
the street.
Waste Water
Sewage
(all
waste
water
from
your
home)
enters
here!
5. Fuel combustion – oxygen is used to burn
fossil fuels and energy, H2O (g), CO2 (g), are
released.
Fossil fuels –fuels formed from dead plants
and animals, such as coal, oil and natural gas.
- these are also called hydrocarbons since they
are made up of hydrogen and carbon though
they may contain oxygen, nitrogen and sulfur
- when burned, these fuels often release
pollutants such as sulfur dioxide, nitrogen
oxides and traces of mercury and lead
6. Industrial Processes – including
electrical power generation, mineral
processing and fertilizer production
• Natural gas – natural gas is composed of
various compounds that can be separated and
used. Methane, propane and butane are used
for heating and ethane is used to make
plastics.
• An unwanted substance is the poisonous
chemical hydrogen sulfide. If gas contains
this chemical, it is called “sour”. To remove
it, sulfur and sulfur dioxide are made. Since
sulfur dioxide is a pollutant, there are
restrictions on the amount released.
• The sulfur is recovered and used to make
fertilizers, paints and steel.
What can YOU DO?
• Use phosphate free laundry
detergent
• biological controls instead of
pesticides
• walk or ride your bike instead
of consuming fossil fuels and
creating pollution
• reduce your solid wastes
• P 181 Quicklab
• Do questions 1-11 on page 190
Topic 1.2
ACIDS AND
BASES
The pH Scale
• pH is a measure of the concentration of
hydrogen ions in solution
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Most Acidic
7= neutral
Most Basic
• pH is a base 10 logarithmic scale.
• Every increment is a power of 10.
• A pH of 5 is 10 times more acidic than
a pH of 6 and 100 times more acidic
than a pH of 7!
• A pH of 12 is 10 times more basic than a
pH of 11.
ACIDS
 taste sour
 soluble in water
 corrosive
conduct electricity
react with metals
most formulas begin with H (hydrogen)
 Examples: HCl - hydrochloric acid
H SO - sulfuric acid
- acids you would find at home include
acetic acid (vinegar) and citric acid (found in
fruits)
2
4
• Acid – a compound that dissolves in
water to form a solution with a pH
lower than 7
- acid rain is produced when chemical
released from industrial processes
combine with water to form acids
that fall with the rain,
SO2 + H2O H2SO3 sulfurous acid,
Nox + H2O  HNO2 and HNO3
nitrous and nitric acid,
CO2 carbonic acid
Acid Rain
• When gases in the atmosphere combine
with water to form rain that is more acid
than normal.
• Kills and deforms living organisms, causes
amphibian eggs not to hatch, increases rate
of rust formation, chemical degradation of
limestone statues and buildings.
• Coal Combustion Acid Rain
• BBC Acid Rain
• Buffers - The slayes of Acid Rain
• Taste bitter
• soluble in water
• feel slippery
• corrosive
• conduct electricity
• react with acids
• found in soaps, detergents
• end in OH (Hydroxide )
Eg. NaOH - sodium hydroxide, fish oils
• Base – a compound that dissolves in
water to form a solution with a pH
higher than 7
- many household cleaners are basic,
from Draino to shampoo and soaps
• Neutral – a pH of 7, it is neither
acidic nor basic
e.g. Distilled Water
Acids can be neutralized by
adding a base (liming), and
bases can be neutralized by
adding an acid.
Neutralization – a reaction where an acid and base
come together to produce water and a salt. This
reaction can be used to neutralize stomach acid or
basic chemical spills, and can help combat the
effects of acid rain.
• In some parts of Canada, rain can have a pH as low
as 3. Acid rain can have devastating effects on
the biotic and abiotic parts of the ecosystem.
•
One way to decrease its effect is to neutralize
lakes by adding lime (calcium hydroxide), producing
water with a neutral pH.
Neutralization
Reaction
• A reaction between an acid and a base
where water (HOH) and salt are formed
• E.g.
HCl + NaOH
hydrochloric acid + Sodium Hydroxide
HOH + NaCl
water +
sodium chloride (salt)
Buffers
• A buffer is a substance that can
neutralize either an acid or a base
• An example of some bases which can
buffer acids are antacids : eno, tums,
pepto bismol.
• Baking soda is basic and can also
buffer an acid.
Measuring pH
1. pH meter – the probe is dipped into a
solution and the meter indicates the
solution’s pH
2. pH indicators – substances which
change in color to indicate pH
ie. litmus paper– blue litmus turns red
in acid, red litmus turns blue in base
- pH paper is more accurate
• a universal indicator – shows a wide variety of
colors, each indicating a different pH when
compared to a color chart (They are a different
color in an acid than in a base)
• There are many other natural indicators
e.g. red cabbage
• Lab: measuring acids and bases
• Bromothymol Blue:
– With acid-yellow
– With base- blue
– In neutral-green
• Lab: Neutralizing Acids p.194
• 5 Human Impacts on the Environment
Unit C Section 1.3
Common Substances Essential to
Living Things
• Of the 25 elements are needed for
growth of living things, carbon, oxygen
and hydrogen are the most common.
• They make up molecules of
carbohydrates, lipids, proteins and
nucleic acids.
• molecules that contain carbon are
organic
• those without carbon are called
inorganic
Nutrients
• elements and compounds needed for living, growing
and reproducing
Macronutrients
• 9 elements that are needed in large amounts.
• C, H, O, N, P, K, Mg, Ca, S.
Micronutrients
• elements needed only in trace amounts
• Eg. Fe, Se
Nutrient
Importance in Plants
Importance in Humans
Nitrogen (N)
- proteins & chlorophyll
- leaf and stem growth
- composition of proteins &
nucleic acids
- growth and repair of tissue
Phosphorus (P)
- root and flower growth
- cellular respiration &
photosynthesis
- composition of bones, teeth &
DNA
- metabolic reactions
Potassium (K)
- stimulates early growth
- starch and protein production
- disease resistance
- chlorophyll production & tuber
formation
- muscle contraction & nerve
impulses
Magnesium (Mg)
- chlorophyll structure
- photosynthesis
- composition of bones & teeth
- absorption of calcium &
potassium
Calcium (Ca)
- cell wall structure
- cell division
- composition of bones & teeth
- blood clotting
- muscle & nerve function
Sulfur (S)
- production of fruits and grains
- protein synthesis
- enzyme activation
- detoxification
Optimum Amounts
• too much or too little of a nutrient can
be harmful to an organism.
• eg. Selenium is an element required in
trace amounts in our diet – too little is
linked to cancer and heart disease, too
much can lead to death.
Types of Organic Molecules
1. Carbohydrates
• made up of C, H and O.
• Foods like pasta, rice and potatoes are rich in complex
carbohydrates.
• There are two categories of carbohydrates:
Simple Sugars:
-one or two subunits long
-glucose is a simple sugar made by
photosynthesis
Complex Carbohydrates:
- long repeating chains of glucose
joined together
- eg. starch, cellulose and
glycogen.
• Starch: used for energy storage in plants
• Glycogen: used for energy storage in
animals
• Cellulose (fibre): found in plant cell walls
2. Lipids
• made up of many C, H and O atoms.
• fats, oils or waxes
•
produced by both plants and animals.
3. Proteins – C, H, O, N
• meats, fish, eggs and dairy all contain protein.
• used for growth and repair and as a source of energy.
• Enzymes are specialized proteins that control the
rate of chemical reactions in the body.
• Proteins are made up of repeating units of amino
acids
• There are 20 different kinds of amino acids.
• Each protein has its own number and arrangement of
amino acids
• Proteins are long chains of amino acids
4. Nucleic Acids – C, H, O, N, P
• largest and most complex molecules in living
things.
• play a major role in heredity and controlling
cell activities.
• Two nucleic acids are DNA (deoxyribonucleic
acid) and RNA (ribonucleic acid)
• They are made of a phosphate, a simple sugar,
and a nitrogenous base.
Unit C Section 1.4
How Organisms Take in Substances
Nutrients
Animals
• Consumers rely on organic
compounds made by plants
for their energy, growth and
repair.
Plants
• Plants rely on inorganic
compounds which they turn
into organic compounds.
PLANTS
1.Passive Transportation
• movement of molecules that does not
require an input of energy
a) Diffusion – the natural movement of
molecules from an area of high concentration
to an area of low concentration. Nutrients
move into plant roots this way until the
concentration on the outside is equal to the
concentration on the inside.
• Diffusion Animation
b) Osmosis – the movement of water molecules
across a membrane due to a concentration
gradient (from high to low concentration).
Water moves into plant roots this way.
• osmosis vs diffusion
osmosis demo with an egg
2. Active Transport
• energy is used to move molecules against the
concentration gradient, from low to high
concentration.
• Roots of plants take up some nutrients this
way.
active and passive transport
ANIMALS
1. Ingestion
• taking food into the body. Animals ingest, then breakdown the
food particles for absorption.
2. Mechanical breakdown
• the physical breakdown of food by chewing.
3. Chemical breakdown
• enzymes breakdown food into its smallest particles through a
process called hydrolysis.
• This happens in the mouth, stomach and intestine.
Hydrolysis
• the addition of water breaks down large food particles into its
smallest form. These molecules have been hydrolyzed.
• Nutrients are transported through the body by the
bloodstream.
NUTRIENT UPTAKE IN DIFFERENT ENVIRONMENTS
• Where an organism lives affects how it takes up
nutrients.
• Substrate – the material on which an organism lives.
Some organisms simply attach themselves to the
substrate, but others actually feed off their
substrate.
Assignment:
• Page 209 # 1 to 7
• and page 211 # 1 to 9