acid rain and organic chemistry - linville · chemistry part 2 acid rain and organic chemistry ....
TRANSCRIPT
Two main factors affect the amount of acid precipitation
1) The amount of NOx and SOx emissions locally
2. Prevailing wind directions
•Wind patterns like the
Jet Stream tend to
push acid clouds
toward Northern
Ontario and Northern
Quebec
• The type of soil has a big impact on the
damage done by acid rain.
– Alberta has mainly sedimentary deposits
which is rich in natural buffer compounds
such as CALCIUM CARBONATE (CaCO3)
– Carbonate ions react with hydronium ions
helping to prevent the soil`s pH from dropping
• Carbonate ions in the
soil act as a buffer
• Alberta’s soil is
alkaline in most
regions due to the
presence of
carbonate.
Acid rain on
limestone (calcium
carbonate rock)
Plant Effects
• Low pH levels can hamper plant growth
• Acid can leach important plant nutrients
from the soil, such as nitrates, phosphates
and potassium
• Some metal ions become soluble at low
pH’s
• One of these is aluminum ions which
cause
– decreased root growth
– decreased absorption of calcium by roots
– kills important bacteria that help to release
nutrients in the soil
Effects on Animals • Low pH can kill animal (such as fish)
directly
• Fish hatchlings are more sensitive to low pH
• Acid can dissolve or soften the shells of some organisms
• Aluminum ions cause excessive mucous production in fish gills, which can lead to suffocation
• Acid can also leach other toxic metal ions such
as, mercury and lead
• Because these metal ions are not removed from
the tissue of animals in the food chain, the
concentration builds up in each trophic level.
Biomagnification
• The tendency for a
pollutant to become
concentrated at
higher levels in a
food chain
SOLUTIONS TO THE PROBLEM OF
ACID RAIN
• The old approach: build stacks tall enough
that the effects spread over a greater area
and become insignificantly small. This did
not work.
• New approach: reduce the emission of
NOx(g) and SOx(g)
• New technologies have been developed to
“catch” the emissions before they are
released.
– ELECTROSTATIC PRECIPITATORS use
electric forces to remove fly ash from coal-
fired power plant stacks (NOx and SOx can
stick to fly ash particles)
Coal burning power plants
• Sulphur compounds are common in some coal deposits
• Can contain more than 5% sulfur
• Coals in Alberta are generally low in sulphur and therefore burn cleaner than coals found elsewhere around the world.
•SCRUBBERS can also be
used to remove NOx and
SOx from gas being emitted
from power plants or other
industrial processes
• the cost of adding scrubbers to old small plants
to meet pollution limits would make them too
expensive to run.
• makes sense to shut down old plants when
prices are low.
• A major component of smog is ground-
level (or “tropospheric”) ozone O3(g) which
is caused by photochemical reactions
involving energy from sunlight
• Ozone irritates and
damages the lungs and
can cause premature
death in people with
respiratory illnesses like
asthma and cystic
fibrosis
• Another dangerous component of smog is
PAN (peroxyacetyl nitrate)
• It is a strong irritant to the lungs
• It results from the reaction of NOx with O3
and VOCs (volatile organic compounds)
PAN
• PAN becomes an issue
when ethanol is used as
an automotive fuel
• carrier for NOx into rural
regions and
causes ozone formation
near the surface
ALTERNATIVE ENERGY
SOURCES
• Alternative energy technologies decrease
the emissions of NOx and SOx by
decreasing fossil fuel combustion
LEGISLATION
• Governments play a large role in
preventing air pollution by setting laws and
regulations
ORGANIC CHEMISTRY AND THE
ENVIRONMENT
• Organic chemistry is the study of complex, carbon-based molecules
• Organic compounds make up or come from living things
• Carbonate (CO3-2), CO2 , CO and
cyanides (CN-) compounds are not considered organic
• Because carbon has four valence
electrons, it can bond to four other atoms
• It forms COVALENT bonds involving the
sharing of electrons
Molecular Models Assignment
Construct the following table. Build each molecule
using the description.
Organic
Compound
Description Drawing of
Structure
Chemical
Formula
Source/Use/Issue
Methane
(Natural
Gas)
A single carbon
bonded to 4
hydrogen atoms
CH4 • Combusted in
my house’s
furnace
• A potent
greenhouse gas
Propane A chain of three
carbons connected
by single bonds
Ethyne
(aka
acetylene)
Two carbons
connected by a
triple bond
Ethanol 2 carbons with a
hydroxyl group
(R-OH)
Benzene A six carbon ring.
Each carbon has
only 1 hydrogen
SIMPLE CARBON CHAINS
• The simplest organic compounds are
called HYDROCARBONS
• Hydrocarbons are made up of carbon and
hydrogen
• They are the main components of fossil
fuels
ALKANES
Hydrocarbon chains that have only single
bonds # of Carbons Name Structure
1 Methane CH4
2 Ethane CH3CH3
3 Propane CH3CH2CH3
4 Butane CH3(CH2)2CH3
5 Pentane CH3(CH2)3CH3
6 Hexane CH3(CH2)4CH3
7 Heptane CH3(CH2)5CH3
8 Octane CH3(CH2)6CH3
9 Nonane CH3(CH2)7CH3
10 Decane CH3(CH2)8CH3
• Because alkanes only have single bonds
between carbons, they have the maximum
number of hydrogen atoms, and are called
SATURATED
• Unsaturated hydrocarbon chains have one
or more double bonds between carbons
• This results in fewer hydrogen atoms, so
are called unsaturated
• Unsaturated fats are easier for enzymes to
break down
ALKENES
• Hydrocarbon chains that have one or more
double bonds.
Ethene: 2 carbons with
a double bond
but-1,3-diene
•4 carbon chain: but
•Double bond: -ene
•2 double bonds: diene
•Bonds are after carbon 1 and carbon 3
ALKYNES
Hydrocarbon chains that have one or more
triple bonds.
• H – C ≡ C – CH3 propyne
• CH3 – CH2 – C ≡ C – CH2 – CH3
hex-3-yne