Chemistry part 2

Acid Rain and Organic Chemistry

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)

A Buffer Reaction

• The arrows pointing left and right mean the

reaction can go in either direction

• hydrogen carbonate acts as a buffer in human

blood in a way similar buffering in Alberta’s soils

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

Root growth stunted by aluminum ions

leeched from soil be acidic water

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

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)

1908 1968

Stack (380 m) at Sudbury

nickel refinery, used to

disperse SOx gases

http://maps.grida.no/go/graphic/acid_rain_in_europe

Effect of acid rain on a forest, Jizera

Mountains, Czech Republic

• 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

A 360 ton scrubber to help cut a power plant's

pollution by 84 percent

• 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.

• new vehicles have

CATALYTIC

CONVERTERS to remove

NOx from vehicle exhaust.

PHOTOCHEMICAL SMOG

• 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

• Ozone also inhibits photosynthesis in plants

• 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

• Simplest organic molecule is methane

(also known as natural gas)

• The “ball-and-stick” model shows the

position of atoms and the locations of

bonds

• Space-filling models show the space

occupied by each atom (including its

electrons)

•Because carbon

can bond to 4 other

atoms, it can form

an almost infinite

variety of

structures

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

• The oil is refined –

separated in different

products used for

different purposes

• The main component

of gasoline is simple

carbon chain called

OCTANE (C8)

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

Structural Formulas

• 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

Propene: 3 carbons with

a double bond

But-1-ene: 4 carbons,

double bond after the 1st

carbon

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

Branched Alkanes

pentane butane

methyl

Methyl butane

Methyl butane

3-ethyl-2-methylhexane

2,3,5-trimethylhexane

Example

• Determine the name of

2,2,4 trimethylpentane