Transcript Acids and Acid Rain - Hudson City School District

VOCABULARY TERMS:
 IONIZATION
 Atoms can gain or lose electrons in order to form ions
DISSOCIATION
 When ionic compounds dissolve in water, their ions
separate from one another
 Steve Spangler Acids and Bases Youtube
Ionization of Water youtube (29 secs)
H+ will quickly
attach to
another water
molecule
What determines if it is becoming
an acid or a base?
reversible
 Dissociation of Water Podcast (2:37) –southern accent
Equilibrium
constant
What is Kw?
 Kw is essentially just an equilibrium constant for the
reactions shown. You may meet it in two forms:
 Based on the fully written equilibrium . . .
 . . . or on the simplified equilibrium:
FYI
A hydrogen ion is also just
a proton.
Nice Nerdy Explanation
 Dissociation of Water (youtube 4:33)
pH
 Indicates the acidity [H3O+] of the solution
 pH = - log [H3O+]
 From the French pouvoir hydrogene
(“hydrogen power” or power of
hydrogen)
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pH
In the expression for [H3O+]
1 x 10-exponent
the exponent = pH
[H3O+] = 1 x 10-pH M
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pH Range: each number is 10 times more
concentrated H+ than the number above it
0
1
2
3 4 5
6
7 8 9 10 11 12 13 14
Basic
Acidic
Neutral
[H+]>[OH-]
[H+] = [OH-]
LecturePLUS Timberlake
[OH-]>[H+]
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Some [H3O+] and pH
[H3O+]
pH
1 x 10-5 M
5
1 x 10-9 M
9
1 x 10-11 M
11
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pH of Some Common Acids
gastric juice
1.0
lemon juice
2.3
vinegar
2.8
orange juice
3.5
coffee
5.0
milk
6.6
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pH of Some Common Bases
blood
7.4
tears
7.4
seawater
8.4
milk of magnesia
10.6
household ammonia
11.0
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Learning Check
A. The [H3O+] of tomato juice is 1 x 10-4 M.
What is the pH of the solution?
1) - 4
2)
4
3)
8
B. The [OH-] of an ammonia solution is
1 x 10-3 M. What is the pH of the solution?
1) 3
2)
11
LecturePLUS Timberlake
3)
-11
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Learning Check
A. The [H3O+] of tomato juice is 1 x 10-4 M.
What is the pH of the solution?
1) - 4
2)
4
3)
8
B. The [OH-] of an ammonia solution is
1 x 10-3 M. What is the pH of the solution?
1) 3
2)
11
LecturePLUS Timberlake
3)
-11
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Learning Check
The pH of a soap is 10. What is the [H3O+] of
the soap solution?
1) 1 x 10 - 4 M
2) 1 x 1010 M
3) 1 x 10 - 10 M
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Solution
Kw = [H3O+ ][OH-] = 1.0 x 10 14
A. [H3O+] = 1.0 x 10 -14
1.0 x 10-10
[OH- ] =
10-4
LecturePLUS Timberlake
or pH 4
27
Buffers
 solution in which the pH of the solution is "resistant"
to small additions of either a strong acid or strong
base.
Buffer Animation
Carbonic acid is a good
blood buffer
Buffer exampls
Where are buffers used?
 chemical research,
 biological research
 industry
 Your body uses buffers to maintain a blood pH of
7.35-7.45,
 massive number of biochemical reactions
involving enzymes.
Acid Rain
Unpolluted rain has a pH of 5.6
Rain with a pH below 5.6 is “acid rain“
CO2 in the air forms carbonic acid
CO2 + H2O
H2CO3
Adds to H+ of rain
H+ (aq) + HCO3-(aq)
H2CO3
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 Formation of acid rain:
 1.
Emission of sulfur and nitrogen oxides
 SO2
26 million tons in 1980
 NO and NO2
22 million tons in 1980
 Mt. St Helens (1980) 400,000 tons SO2
Sources of Acid Rain
Power stations
Oil refineries
Coal with high S content
Car and truck emissions
Bacterial decomposition, and lighting
hitting N2
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 2. Reactions in the atmosphere form SO3

2SO2 + O2
2 SO3
 3. Reactions with atmosphere water form acids



SO3 + H2O
NO + H2O
HNO2 + H2O
H2SO4 sulfuric acid
NO2 nitrous acid
HNO3 nitric acid
Effects of Acid Rain
Leaches Al from soil, which kills fish
Fish kills in spring from runoff due to
accumulation of large amounts of acid in snow
Dissolves waxy coatings that protect leaves from
bacteria
Corrodes metals, textiles, paper and leather
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Criteria Air Pollutants: NOx
and SOx
 200+ now-fishless
lakes in Adirondacks
 Little Echo Pond,
Franklin, NY
pH = 4.2
 Thousands of lakes in
Canada (Ontario,
Quebec, New
Brunswick) nowfishless
http://www.elmhurst.edu/~chm/vchembook/194acidraineffects.html
pH Scale Matching
 Quia - The pH Scale
 Write the order you think these are from pH 1-14.
 1 Stomach Fluids
 7 Pure Water
 11 Rolaids, Tums
 13 Bleach
 2 Lemon Juice
 5 Coffee
 3 Vinegar
 8 Blood
 10 Borax
 14 Lye
 4 Tomatoes
 6 Milk
 9 Baking Soda
 12 Household Ammonia
ACID RAIN MOVIE
 Acid Rain - Our Changing Planet
– UMAC
 When precipitation goes below pH 5.6.
 Comes from burning of fossil fuels (cars, factories,
airplanes). Sulfur and nitric oxides form sulfuric
acid and
nitric acid.
Main Pollutant of Acid Rain
Forest Destroyed by Acid Rain
Canada
U.S.
Not just in US.
 China Guangzhou Shajiao on the Pearl River
 India Korba
England
Effects on Wildlife
Generally, the young of most species are
more sensitive to environmental conditions
than adults.
At pH 5, most fish eggs cannot hatch.
At lower pH levels, some adult fish die.
Some acid lakes have no fish.
Young fish
Wuhan dead fish
(China)
Acid Rain Stream
Norilsk, in Russia's remote Artic region, is
accused of being world's largest producer of
acid rain.