Tro’s Chemistry Chapter 15 – Acids and Bases
Page 1 of 12
Acknowledgements: Many of the images are adopted from Tro’s textbook, the only purpose of which is to
enhance student learning.
Key terms, concepts, skills: Refer to pp 708 – 710.
Review questions: 2 – 32 minus 3.
Suggested problems: 37, 39, 41, 45, 47, 51, 53, 55, 63, 67, 79, 85, 87, 89, 103, 107, 115, 121, 123.
15.1 & 2 Introduction – The Nature of Acids and Bases
• the cells that line your stomach produce hydrochloric acid – to kill unwanted bacteria, to help break down
food; to activate enzymes that break down food
• if the stomach acid backs up into your esophagus, it irritates those tissues, resulting in heartburn; acid
reflux; GERD = gastroesophageal reflux disease = chronic leaking of stomach acid into the esophagus
9 mild cases of heartburn can be cured by neutralizing the acid in the esophagus – swallowing saliva
which contains bicarbonate ion; taking antacids that contain hydroxide ions and/or carbonate ions
Properties of acids
• sour taste
• react with “active” metals; i.e., Aℓ, Zn, Fe, but not Cu, Ag, or Au
2 Aℓ + 6 HCℓ Æ 2 AℓCℓ 3 + 3 H2
9 corrosive
• react with carbonates, producing CO2; marble, baking soda, chalk, limestone
CaCO3 + 2 HCℓ Æ CaCℓ2 + CO2 + H2O
• change color of vegetable dyes; blue litmus turns red
• react with bases to form ionic salts
Structure of acids
• binary acids have acid hydrogens
attached to a nonmetal atom; HCℓ, HF
• electronegativity difference
• polarizabilitye
• oxy acids have acid hydrogen(s)
attached to an oxygen atom; H2SO4,
HNO3
• carboxylic acids have COOH group
i.e.; formic acid, HCOOH, acetic acid,
CH3COOH
• the H is on the COOH is the only
acidic H in the formula
Tro’s Chemistry / Chapter 15 – Acids and Bases / Page 2 of 12
Properties of bases
• also known as alkalis
• taste bitter; alkaloids = plant product that is alkaline, often poisonous
• solutions feel slippery
• change color of vegetable dyes – red litmus turns blue
• react with acids to form ionic salts – neutralization
Structure of bases
• most ionic bases contain OH– ions; NaOH, Ca(OH)2
• some contain CO32– ions; CaCO3 NaHCO3
• molecular bases contain structures that react with H+; mostly amine groups (nbp or –ve charge)
15.3 Definitions of Acids and Bases
Arrhenius Theory
• bases dissociate in water to produce OH– ions and cations
9 ionic substances dissociate in water; NaOH(aq) Æ Na+(aq) + OH–(aq)
• acids ionize in water to produce H+ ions and anions
9 because molecular acids are not made of ions, they cannot dissociate
9 they must be pulled apart, or ionized, by the water; HCℓ(aq) Æ H+(aq) + Cℓ–(aq)
9 in formula, ionizable H written in front; HC2H3O2(aq) Æ H+(aq) + C2H3O2–(aq)
Hydronium ion
• the H+ ions produced by the acid are so reactive (bare protons) they cannot exist in water
• instead, they react with a water molecule(s) to produce complex ions, mainly hydronium ion, H3O+
H+ + H2O Æ H3O+
9 there are also minor amounts of H+ with multiple water molecules, H(H2O)n+
Arrhenius Acid-Base Reactions
• the H+ from the acid combines with the OH– from the base to make a molecule of H2O
9 it is often helpful to think of H2O as H––OH
• the cation from the base combines with the anion from the acid to make a salt
acid +
base
Æ
salt
+ water
HCℓ(aq) + NaOH(aq) Æ NaCℓ(aq) + H2O(l)
Problems with Arrhenius theory:
• does not explain why molecular substances, like NH3, dissolve in water to form basic solutions – even
though they do not contain OH– ions
• does not explain how some ionic compounds, like Na2CO3 or Na2O, dissolve in water to form basic
solutions – even though they do not contain OH– ions
• does not explain why molecular substances, like CO2, dissolve in water to form acidic solutions ––
even though they do not contain H+ ions
• does not explain acid-base reactions that take place outside aqueous solution
Tro’s Chemistry / Chapter 15 – Acids and Bases / Page 3 of 12
Brønsted-Lowry Theory
• in a Brønsted-Lowry Acid-Base reaction, an H+ is transferred
9 does not have to take place in aqueous solution; a broader definition than Arrhenius
• acid is H+ donor, base is H+ acceptor
9 base structure must contain an atom with an unshared pair of electrons
• in an acid-base reaction, the acid molecule gives an H+ to the base molecule
: A– + H––B+
H––A + : B
• Brønsted-Lowry acids are H+ donors
9 any material that has H can potentially be a Brønsted-Lowry acid
• HCℓ(aq) is acidic because HCℓ transfers an H+ to H2O, forming H3O+ ions
9 water acts as base, accepting H+
HCℓ(aq) + H2O(l) → Cℓ–(aq) + H3O+(aq)
acid
base
•
•
Brønsted-Lowry bases are H+ acceptors
9 any material that has atoms with lone pairs can potentially be a Brønsted-Lowry base
NH3(aq) is basic because NH3 accepts an H+ from H2O, forming OH–(aq)
9 water acts as acid, donating H+
NH3(aq) + H2O(l)
base
NH4+(aq) + OH–(aq)
acid
Amphoteric Substances
• amphoteric substances can act as either an acid or a base
9 have both transferable H and atom with lone pair of electron
• water acts as base, accepting H+ from HCℓ; HCℓ(aq) + H2O(l) → Cℓ–(aq) + H3O+(aq)
• water acts as acid, donating H+ to NH3; NH3(aq) + H2O(l)
NH4+(aq) + OH–(aq)
Q# 39. H2PO4– is amphoteric. Write equations that demonstrate both its acidic nature and its basic
nature.
Conjugate Pairs
• In a Brønsted-Lowry Acid-Base reaction, the original base becomes an acid in the reverse reaction,
and the original acid becomes a base in the reverse process
• each reactant and the product it becomes is called a conjugate pair
• the original base becomes the conjugate acid; and the original acid becomes the conjugate base
(Refer to Example 15.1 and Practice 15.1 for problem solving help and hint.)
Q# 37. Write the formula for the conjugate base of each of the following acids.
a. HCℓ
b. H2SO3
c. HCHO2
d. HF
15.4 Acid Strength and Acid Dissociation Constant, Ka
Strong vs. weak
• a strong acid is a strong electrolyte – practically all the acid molecules ionize, →
• a strong base is a strong electrolyte – practically all the base molecules form OH– ions, either through
dissociation or reaction with water, →
• a weak acid is a weak electrolyte – only a small percentage of the molecules ionize,
Tro’s Chemistry / Chapter 15 – Acids and Bases / Page 4 of 12
•
a weak base is a weak electrolyte – only a small percentage of the base molecules form OH– ions,
either through dissociation or reaction with water,
Strong acid
• The stronger the acid, the more willing it is to donate H+, use water as the standard base
• strong acids donate practically all their H+’s, 100% ionized in water, strong electrolyte
• [H3O+] = [strong acid]
• List of 6 strong acids
Weak acid
• weak acids donate a small fraction of their H’s
9 most of the weak acid molecules do not donate H to water; <1% ionized in water
• [H3O+] << [weak acid]
Polyprotic acid
• have more than one ionizable H
9 the ionizable H’s may have different acid strengths or be equal
9 1 H = monoprotic, HCℓ; 2 H = diprotic, H2SO4; 3 H = triprotic, H3PO4
• polyprotic acids ionize in steps – each ionizable H removed sequentially
• removing of the first H automatically makes removal of the second H harder –– H2SO4 is a stronger
acid than HSO4−
General Trends in Acidity
• the stronger an acid is at donating H, the weaker the conjugate base is at accepting H
• higher oxidation number = stronger oxyacid
9 H2SO4 > H2SO3; HNO3 > HNO2
• cation stronger acid than neutral molecule; neutral stronger acid than anion
9 H3O+ > H2O > OH–; NH4+ > NH3 > NH2–
9 base trend opposite
Acid Ionization Constant, Ka
• acid strength measured by the size of the equilibrium constant when react with H2O
HA + H2O
A– + H3O+
• the equilibrium constant is called the acid ionization constant, Ka
9 larger Ka = stronger acid
Ka =
[A − ] × [H 3 O + ]
[HA]
Q# 41. Classify each of the following acids as strong or weak. If the acid is weak, write an expression for
the acid ionization constant (Ka).
a.
b.
c.
d.
HNO3
HCℓ
HBr
H2SO3
Q# 45. Pick the stronger base from each of the following pairs:
a. F– or Cℓ–
b. NO2– or NO3–
c. F– or CℓO–
15.5 Autoionization of Water and pH
• Water is actually an extremely weak electrolyte
• about 1 out of every 10 million water molecules form ions through a process called autoionization
H2O Æ H+ + OH–
H2O + H2O Æ H3O+ + OH–
Tro’s Chemistry / Chapter 15 – Acids and Bases / Page 5 of 12
•
+
all aqueous solutions contain both H3O and OH–
9 the concentration of H3O+ and OH– are equal in water
9 [H3O+] = [OH–] = 10–7 M @ 25°C
Ion Product of Water
• the product of the H3O+ and OH– concentrations is always the same number
• the number is called the ion product of water and has the symbol Kw
• [H3O+] x [OH–] = Kw = 1 x 10–14 @ 25°C
9 if you measure one of the concentrations, you can calculate the other
• as [H3O+] increases the [OH–] must decrease so the product stays constant – inversely proportional
Acidic and Basic Solutions
• all aqueous solutions contain both H3O+ and OH– ions
• neutral solutions have equal [H3O+] and [OH–]
[H3O+] = [OH–] = 1 x 10–7
+
–
• acidic solutions have a larger [H3O ] than [OH ]
[H3O+] > 1 x 10–7; [OH–] < 1 x 10–7
–
+
[H3O+] < 1 x 10–7; [OH–] > 1 x 10–7
• basic solutions have a larger [OH ] than [H3O ]
(Refer to Example 15.2 and Practice 15.2 for problem solving help and hint.)
pH
• the acidity/basicity of a solution is often expressed as pH
• pH = -log[H3O+], [H3O+] = 10–pH
9 exponent on 10 with a negative sign
9 pHwater = –log[10–7] = 7
9 need to know the [H+] concentration to find pH
• pH < 7 is acidic; pH > 7 is basic, pH = 7 is neutral
• the lower the pH, the more acidic the solution; the higher the pH, the more basic the solution
9 1 pH unit corresponds to a factor of 10 difference in acidity
• normal range 0 to 14
9 pH 0 is [H+] = 1 M, pH 14 is [OH–] = 1 M
9 pH can be negative (very acidic) or larger than 14 (very alkaline)
(Refer to Example 15.3-4 and Practice 15.3-4 for problem solving help and hint.)
pOH
• another way of expressing the acidity/basicity of a solution is pOH
• pOH = −log[OH−], [OH−] = 10−pOH
9 pOHwater = −log[10−7] = 7
9 need to know the [OH−] concentration to find pOH
• pOH < 7 is basic; pOH > 7 is acidic, pOH = 7 is neutral
Relationship between pH and pOH
• the sum of the pH and pOH of a solution = 14.00
9 at 25°C
9 can use pOH to find pH of a solution
Yin-Yang coexistence
[H 3O + ][OH - ] = K w = 1.0 × 10 −14
− log [H O + ][OH - ] = − log 1.0 × 10 −14
( (
))
(
)
(− log([H O ])) + (− log([OH ])) = 14.00
3
+
3
pH + pOH = 14.00
Tro’s Chemistry / Chapter 15 – Acids and Bases / Page 6 of 12
–
Q# 47. Calculate [OH ] in each of the following aqueous solutions at 25 °C, and classify the solution as
acidic or basic.
[H3O+] =
[OH–] =
Acidic or basic
a.
1.2 x 10–8 M
b.
8.5 x 10–5 M
c.
3.5 x 10–7 M
Q# 51. Complete the following table. (All solutions are at 25 °C.)
[H3O+]
[OH–]
a)
b)
pH
3.15
3.7 x 10–9 M
c)
d)
Acidic/Basic
11.1
1.6 x 10
–11
M
Q# 53. Like all equilibrium constants, the value of Kw depends on temperature. At body temperature
(37°C), Kw = 2.4 x 10–14. What is the [H3O+] and pH of pure water at body temperature?
Q# 55. For each of the following strong acid solutions, determine [H3O+], [OH–], and pH.
a. 0.25 M HCℓ
b. 0.015 M HNO3
c. a solution that is 0.052 M in HBr and 0.020 M in HNO3
d. A solution that is 0.655% HNO3 by mass (Assume a density of 1.01 g/mL for the solution.)
Q# 63. Determine the pH of an HNO2 solution of each of the following concentrations. In which cases can
you not make the simplifying assumption that x is small?
a. 0.500 M
b. 0.100 M
c. 0.0100 M
Q# 67. A 0.185 M solution of a weak acid (HA) has a pH of 2.95. Calculate the acid ionization constant
(Ka) for the acid.
Tro’s Chemistry / Chapter 15 – Acids and Bases / Page 7 of 12
Q# 79. For each of the following strong base solutions, determine [OH–], [H3O+], pH, and pOH.
a. 0.15 M NaOH
b. 1.5 x 10–3 M Ca(OH)2
c. 4.8 x 10–4 M Sr(OH)2
d. 8.7 x 10–5 M KOH
pK
•
•
•
•
a way of expressing the strength of an acid or base is pK
pKa = −log(Ka), Ka = 10−pKa
pKb = −log(Kb), Kb = 10−pKb
the stronger the acid, the smaller the pKa
9 larger Ka = smaller pKa because it is the –log
Q# 85. Write equations showing how each of the following weak bases ionizes water to form OH–. Also
write the corresponding expression for Kb.
equation
Kb expression
a. NH3
b. HCO3–
c.
CH3NH2
Q# 87. Determine the [OH–], pH, and pOH of a 0.15 M ammonia solution.
Q# 89. Caffeine (C8H10N4O2) is a weak base with a pKb of 10.4. Calculate the pH of a solution containing
a caffeine concentration of 455 mg/L.
15.6 Finding the [H3O+] and pH of Strong and Weak Acid Solutions
Finding the pH of a Strong Acid
• there are two sources of H3O+ in an aqueous solution of a strong acid – the acid and the water
• for the strong acid, the contribution of the water to the total [H3O+] is negligible
9 shifts the Kw equilibrium to the left so far that [H3O+]water is too small to be significant
¾ except in very dilute solutions, generally < 1 x 10–4 M
Tro’s Chemistry / Chapter 15 – Acids and Bases / Page 8 of 12
•
•
+
for a monoprotic strong acid [H3O ] = [HA]
9 for polyprotic acids, the other ionizations can generally be ignored
0.10 M HCℓ has [H3O+] = 0.10 M and pH = 1.00
Finding the pH of a Weak Acid
• there are also two sources of H3O+ in and aqueous solution of a weak acid – the acid and the water
• however, finding the [H3O+] is complicated by the fact that the acid only undergoes partial ionization
• calculating the [H3O+] requires solving an equilibrium problem for the reaction that defines the acidity
of the acid
HA + H2O
A− + H3O+
(Refer to Example 15.5-8 and Practice 15.5-8 for problem solving help and hint.)
Percent Ionization
• another way to measure the strength of an acid is to determine the percentage of acid molecules that
ionize when dissolved in water – this is called the percent ionization
9 the higher the percent ionization, the stronger the acid
Percent Ionization =
•
molarity of ionized acid
× 100%
initial molarity of acid
since [ionized acid]equil = [H3O+]equil
Percent Ionization =
[H 3O + ]equil
[HA]init
×100%
(Refer to Example 15.9 and Practice 15.9 for problem solving help and hint.)
Finding the pH of Mixtures of Acids
• generally, you can ignore the contribution of the weaker acid to the [H3O+]equil
• for a mixture of a strong acid with a weak acid, the complete ionization of the strong acid provides
more than enough [H3O+] to shift the weak acid equilibrium to the left so far that the weak acid’s
added [H3O+] is negligible
• for mixtures of weak acids, generally only need to consider the stronger for the same reasons
9 as long as one is significantly stronger than the other, and their concentrations are similar
(Refer to Example 15.10 and Practice 15.10 for problem solving help and hint.)
15.7 Base Solutions
Strong Bases
• the stronger the base, the more willing it is to accept H+
9 use water as the standard acid
• for strong bases, practically all molecules are dissociated into OH– or accept H+’s
9 strong electrolyte
9 multi-OH strong bases completely dissociated
• [HO–] = [strong base] x (# OH)
• List of 6 strong bases
• Refer to Example 15.11 and Practice 15.11 for problem solving help and hint.
Weak Bases
• in weak bases, only a small fraction of molecules accept H+’s
9 weak electrolyte
9 most of the weak base molecules do not take H+ from water
9 much less than 1% ionization in water
• [HO–] << [weak base]
• finding the pH of a weak base solution is similar to finding the pH of a weak acid
• Refer to Example 15.11&12 and Practice 15.11&12 for problem solving help and hint.
Tro’s Chemistry / Chapter 15 – Acids and Bases / Page 9 of 12
15.8 The Acid-Base Properties of Ions and Salts
• salts are water soluble ionic compounds
• salts that contain the cation of a strong base and an anion that is the conjugate base of a weak acid
are basic
9 NaHCO3 solutions are basic
¾ Na+ is the cation of the strong base NaOH
¾ HCO3– is the conjugate base of the weak acid H2CO3
• salts that contain cations that are the conjugate acid of a weak base and an anion of a strong acid are
acidic
9 NH4Cℓ solutions are acidic
¾ NH4+ is the conjugate acid of the weak base NH3
¾ Cℓ– is the anion of the strong acid HCℓ
Anions as Weak Bases
• every anion can be thought of as the conjugate base of an acid, therefore, every anion can potentially
be a base
9 A–(aq) + H2O(l)
HA(aq) + OH–(aq)
• the stronger the acid is, the weaker the conjugate base is
9 an anion that is the conjugate base of a strong acid is pH neutral
Cℓ–(aq) + H2O(l) ← HCℓ(aq) + OH–(aq)
¾ since HCℓ is a strong acid, this equilibrium lies practically completely to the left
9 an anion that is the conjugate base of a weak acid is basic
F–(aq) + H2O(l)
HF(aq) + OH–(aq)
¾ since HF is a weak acid, the position of this equilibrium favors the right
• Refer to Example 15.13 and Practice 15.13 for problem solving help and hint.
Relationship between Ka of an Acid and Kb of Its Conjugate Base (Ka x Kb = Kw)
[
1.0 × 10 −14 = K w = ⎡⎢⎣ H 3O + ⎤⎥⎦ OH −
]
(Refer to Example 15.14 and Practice 15.14 for problem solving help and hint.)
Tro’s Chemistry / Chapter 15 – Acids and Bases / Page 10 of 12
Polyatomic Cations as Weak Acids
• some cations can be thought of as the conjugate acid of a base,
9 others are the counterions of a strong base
• therefore, some cation can potentially be an acid
9 MH+(aq) + H2O(l)
MOH(aq) + H3O+(aq)
• the stronger the base is, the weaker the conjugate acid is
9 a cation that is the counterion of a strong base is pH neutral
9 a cation that is the conjugate acid of a weak base is acidic
NH4+(aq) + H2O(l)
NH3(aq) + H3O+(aq)
¾ since NH3 is a weak base, the position of this equilibrium favors the right
Metal Cations as Weak Acids
• cations of small, highly charged metals are weakly acidic
9 alkali metal cations and alkali earth metal cations pH neutral
9 cations are hydrated
Aℓ(H2O)63+(aq) + H2O(l)
Aℓ(H2O)5(OH)2+(aq) + H3O+(aq)
• Refer to Example 15.15 and Practice 15.15 for problem solving help and hint.
Classifying Salt Solutions as Acidic, Basic, or Neutral
• if the salt cation is the counterion of a strong base and the anion is the conjugate base of a strong
acid, it will form a neutral solution
NaCℓ
Ca(NO3)2 KBr
• if the salt cation is the counterion of a strong base and the anion is the conjugate base of a weak
acid, it will form a basic solution
NaF Ca(C2H3O2)2
KNO2
• if the salt cation is the conjugate acid of a weak base and the anion is the conjugate base of a strong
acid, it will form an acidic solution
NH4Cℓ
• if the salt cation is a highly charged metal ion and the anion is the conjugate base of a strong acid, it
will form an acidic solution
Aℓ(NO3)3
• if the salt cation is the conjugate acid of a weak base and the anion is the conjugate base of a weak
acid, the pH of the solution depends on the relative strengths of the acid and base
9 NH4F since HF is a stronger acid than NH4+, Ka of NH4+ is larger than Kb of the F–; therefore
the solution will be acidic
• Refer to Example 15.16 and Practice 15.16 for problem solving help and hint.
Q# 93. Which of the following anions act as weak bases in solution? For those anions that are basic,
write an equation that shows how the anion acts as a base.
a. Br–
b. CℓO–
c. CN–
d. Cℓ–
Q# 99. Determine whether each of the following salts will form a solution that is acidic, basic, or pHneutral.
b. NaF
c. CaBr2
d. NH4Br
e. C6H5NH3NO2
a. FeCℓ3
Q# 103. Determine the pH of each of the following solutions:
a. 0.10 M NH4Cℓ
b. 0.10 M NaC2H3O2
c. 0.10 M NaCℓ
Tro’s Chemistry / Chapter 15 – Acids and Bases / Page 11 of 12
15.9 Polyprotic Acids
• since polyprotic acids ionize in steps, each H+ has a separate Ka
• Ka1 >> Ka2 > Ka3
• generally, the difference in Ka values is great enough so that the second ionization does not
happen to a large enough extent to affect the pH
9 most pH problems just use first ionization
9 except H2SO4 ⇒ use [H2SO4] as the [H3O+] for the second ionization
2−
• [A ] = Ka2 as long as the second ionization is negligible
• Refer to Example 15.17-19 and Practice 15.17-19 for problem solving help and hint.
Q# 107. Write chemical equations and corresponding equilibrium expressions for each of the three
ionization steps of phosphoric acid.
15.10 Acid Strength and Molecular Structure
Strengths of Binary Acids
• the more δ+H––Yδ− polarized the bond, the more acidic the bond
• the stronger the H––Y bond, the weaker the acid
• binary acid strength increases to the right across a period
9 H––C < H––N < H––O < H––F
• binary acid strength increases down the column
9 H––F < H––Cℓ < H––Br < H––I
Strengths of Oxyacids, H––O––Y
• the more electronegative the Y atom, the stronger the acid
9 helps weakens the H––O bond
• the more oxygens attached to Y, the stronger the acid
9 further weakens and polarizes the H––O bond
15.11 Lewis Acids and Bases
• electron sharing
• electron donor = Lewis Base = nucleophile
must have a lone pair of electrons
• electron acceptor = Lewis Acid = electrophile
electron deficient
• when Lewis Base gives electrons from lone pair to Lewis Acid, a covalent bond forms between the
molecules
• Nucleophile: + Electrophile
Nucleophile:Electrophile
product called an adduct
Q# 115. Based on their molecular structure, pick the stronger acid from each of the following pairs of
binary acids. Explain your reasoning.
a. HF and HCℓ
b. H2O or HF
c.
H2Se or H2S
Tro’s Chemistry / Chapter 15 – Acids and Bases / Page 12 of 12
Q# 121. Classify each of the following as either a Lewis acid or a Lewis base.
a. Fe3+
b. BH3
c. NH3
d. F–
Q# 123. Identify the Lewis acid and Lewis base from among the reactants in each of the following
equations:
a. Fe3+(aq) + 6 H2O(I) → Fe(H2O)63+(aq)
b. Zn2+(aq) + 4 NH3(aq) ↔ Zn(NH3)42+(aq)
c.
(CH3)3N(g) + BF3(g) ↔ (CH3)3NBF3(s)
15.12 Acid Rain
What Is Acid Rain?
• natural rain water has a pH of 5.6
9 naturally slightly acidic due mainly to CO2
• rain water with a pH lower than 5.6 is called acid rain
• acid rain is linked to damage in ecosystems and structures
What Causes Acid Rain?
• many natural and pollutant gases dissolved in the air are nonmetal oxides
9 CO2, SO2, NO2
• nonmetal oxides are acidic
CO2 + H2O
H2CO3
2 SO2 + O2 + 2 H2O
2 H2SO4
• processes that produce nonmetal oxide gases as waste increase the acidity of the rain
9 natural – volcanoes and some bacterial action
9 man-made – combustion of fuel
• weather patterns may cause rain to be acidic in regions other than where the nonmetal oxide is
produced
Damage from Acid Rain
• acids react with metals, and materials that contain carbonates
• acid rain damages bridges, cars, and other metallic structures
• acid rain damages buildings and other structures made of limestone or cement
• acidifying lakes affecting aquatic life
• dissolving and leaching more minerals from soil
9 making it difficult for trees
Acid Rain Legislation
• 1990 Clean Air Act attacks acid rain
9 force utilities to reduce SO2
• result is acid rain in northeast stabilized and beginning to be reduced