Transcript Science 30 Chemistry

Science 30 Chemistry
Chapter 2: Chemical legacy of
human activity.
Body Chemistry
2.1- Organic compounds
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3 main types of organic compounds:
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Alkanes – single bonds, saturated.
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Alkenes- double bonds, unsaturated.
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General formula CnH2n+2
General formula CnH2n
Alkynes- triple bonds, unsaturated.
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General formula CnH2n-2
Classifications of Hydrocarbons
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Hydrocarbons can be classified as follows:
A) Naming system for Hydrocarbons
1.
2.
Name the longest chain
• for root of the word see Data Booklet pg 10
(meth, eth . . .)
• Ending = ane, ene or yne
Number the chain so branches are at the lowest
possible position numbers.
- If a double or triple bond, number closest to the bond.
3.
Name the branches
• Root of word same as above
• Ending = yl
Naming cont.
4. Put names together in this order: position #,
branch, parent chain
• Multiple branches? Put branches in
alphabetical order.
• Numbers are separated by commas.
• Words and numbers are separated by dashes.
• Multiples of the same kind of branch use a
prefix to indicate how many (di, tri . . .).
• Double or triple bonds must have the carbon
# inserted and then the ending.
Name the Following Hydrocarbons
H H H H H H H H
H C C C C C C C C H
H H H H H H H H
H
C
H
H
H
C
C
C
C
C
C
C
H
H
H
H
H
H
H
CH = C-CH2-CH2-CH3
H
B) Cyclic Hydrocarbons
These are hydrocarbons that form rings;
are also referred to as aromatic or phenyl
rings.
 Are double bonded alkenes; general
formula is CnHn
 Benzene is a hexagonal structure, all
aromatic compounds are.

naphthalene
benzene
Benzene
Aromatics are naturally occurring, present
in natural resources (coal and petroleum).
 Benzene is a carcinogen and the level in
natural gas is regulated in Canada.
 When natural gas spills, the soil is
contaminated with water soluble
aromatics.
 Clean up must be completed through
remediation (removal from groundwater,
soil or surface water).

1) Remediation
Involves the removal or breakdown of
hydrocarbons in the gasoline.
 Harmful aromatics can contaminate
drinking water, ground water and cause
illness.
 Bacteria in soil naturally breakdown
organics, but benzene is very stable and is
not easily broken down.
 Because of the high stability, benzene is
classified as a POP (persistent organic
pollutant).

Soil remediation
Whyte Avenue soil remediation
Bioremediation
2) Benzene structure and stability
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Benzene has properties similar to both
alkanes and alkenes.
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Resonance is responsible for this:
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Stability- high stability similar to alkenes.
Reactivity- high reactivity similar to alkanes.
Within aromatic ring, electrons are shared by
all carbons.
Responsible for stability.
High temperatures needed to break down
benzene = contained in gasoline
emissions.
3) PAH’s
Polycyclic Aromatic hydrocarbons
produced by incomplete combustion of
oils.
 Found on charbroiled foods, smoke in
forest fires and vehicle exhaust,
 Combine with DNA to form structures that
result in mutations.

Benzopyrene
C) Functional groups
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In addition to hydrogen and carbon organic
compounds can also contain other elements, often
in specific arrangements.
Functional Group:
 certain arrangement of atoms within a molecule
 determines properties of the molecule
Molecules are classified based on functional group
Example of a functional group
 Hydroxyl
• functional group for alcohol
• R – OH
• NOTE: R represents any # of carbons
Halogenated Hydrocarbons
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Functional group:
 One or more H is replaced by a halogen
 Halogens include:
fluorine, chlorine, bromine, and iodine
Naming Halogenated Hydrocarbons:
 Use a prefix to indicate the number of halogens
 Write chloro, fluoro, bromo, or iodo to indicate which
halogen is present
 Name the parent chain
Examples:
trichloromethane
tetrachloromethane
CFCs
Was used as a cleaner,
found to be a carcinogen
Damages
ozone layer
CFC’s
(ChloroFluoroCarbons
formed from carbon and
halogens) are products
common in air
conditioners, aerosols,
solvents and styrofoam
packaging. These
products make their way
to the upper atmosphere
and break ozone down.
Cl + O3 = ClO + O2
ClO + O = Cl + O2
Ozone Layer
A single chlorine atom removes about 100,000 ozone
molecules before it is taken out of operation by other
substances.
Ozone
The chemical formula for ozone is O3. It can be
produced in the upper atmosphere when UV rays strike
O2.
O2 + UV -> O + O (1)
O + O2 -> O3 (2)
Ozone is also continually being broken down by UV
rays.
O3 + UV->
O2 + O
(3)
O + O3 ->
O2 + O2
(4)
A balance between these two reactions has resulted in a
layer of ozone surrounding the planet.
These reactions are
responsible for
absorption of 9799% of the sun's
high frequency UV
waves..
Ultraviolet light is light with
wavelengths between 150
and 300nm
UV-B radiation exposure causes
increased cancer, eye cataracts,
weakened immune system and
reduced plant yields.
"There has been a great deal of recent attention to the
suspected increase in amphibian deformities. However, most
reports have been anecdotal, and no experiment in the field
under natural conditions had been performed previously,"
Even though the ozone is
being destroyed naturally, it
is disappearing faster than
possible without other
factors influencing it.
The first global agreement to restrict CFCs came
with the signing of the MONTREAL PROTOCOL in
1987 ultimately aiming to reduce them by half by the
year 2000. The main CFCs will not be produced by
any of the signing countries after the end of 1995,
except for a limited amount for essential uses, such
as for medical sprays.
Other Halogenated Compounds
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Many other compounds cause damage to
the environment:
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DDT – used for mosquito control
Dioxin – byproduct of chlorinated processes
Furan – byproduct of chlorinated processes
2.2) Alcohols, Carboxylic Acids and Esters
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3 types of functional groups in organic
compounds:
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Alcohols: OH group
Carboxylic acids: COOH
Esters: OH and COOH
a) Alcohols
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Have hydroxyl in them (OH)
and end in –ol.
Hydroxyl group attracts water
particles; causes antifreeze to
slow freezing of gas lines.
Uses and common examples:
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Solvents, fuels, disinfectants,
pharmaceuticals.
Methanol, ethanol, glycol and
isopropanol.
Alcohols contain Hydroxyl
•
•
•
Naming Alcohols:
 Omit ‘e’ at end of the name
 Change ending to ‘ol’
Properties:
 Hydroxyl group does not dissociate in water, therefore
alcohols are NOT basic
 Liquid at room temp
 Distinct odour
Examples:
Methanol
poisonous
Ethanol
in alcoholic
beverages
isopropanol
Rubbing alcohol
b) Carboxylic acids
Carbon atom joined to a
single oxygen atom and one
oxygen joined to a
hydrogen (COOH).
 Lactic acid is the name of a
carboxylic acid produced
during exercise;
biphosphate is used to
buffer it in the body.
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Carboxylic Acids Contain Carboxyl
Groups
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Naming Carboxylic Acids:
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Properties:
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Omit ‘e’ at end of the name
Change ending to ‘oic acid’
Weak acids because the OH donates a proton
NOTE: the OH in carboxylic acids behaves differently
than the OH in alcohols
Examples:
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Vinegar
Citric acid
Lactic acid
c) Esters
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Formed by carboxylic acids and
alcohols reacting.
Naturally occurring (fatty acids in
bodies) and artificially
(cosmetics/food industry).
Water is a by product of the
formation of an ester.
Used to add a smell or color to a
compound (e.g. Licorice).
Esters
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Examples of esters:
 Cologne
 Aftershave
 pleasant odours / flavours in food
Alcohols and carboxylic acids react to form esters
An H is removed from the alcohol and an ‘OH’ from
the acid- water is formed.
Functional group for ester:
Naming an ester:
 R’ is the alcohol, change the ending to ‘yl’
 R is the acid – drop ‘ic acid’ and change ending
to ‘ate’
d) Polyesters
Polyester forms plastic: created by many
alcohols and carboxylic acids reacting,
forming long chains (polymers).
 These filaments are used to make many
products:
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Towropes
PFD straps
T-shirts
Wakeboards
Dacron
e) Bioplastics
Plastics are not
biodegradable; they do
not breakdown in land
fills (up to 300 years).
 Bioplastics are
completely
biodegradable but have
the strength of plastics.
 Produced by tissues of
plants or from bacteria
cells.

Water Pollution