Title: Acids and Bases
1Acids and Bases
2Acids Compounds that contain one or more
hydrogen ions (H) when dissolved in
water Bases Compounds that contain one or
more hydroxide ions (OH-) when dissolved in water
3Arrhenius Acid
A substance that dissociates in water to form
hydrogen ions (H) that is, an acid increases
the concentration of H ions in an aqueous
solution
4Arrhenius Base
a substance that dissociates in water to form
hydroxide (OH-) ions that is, a base increases
the concentration of OH- ions in an aqueous
solution.
5Bronsted-Lowry Acid
A molecule or ion that is able to lose, or
"donate," a hydrogen cation (proton,
H) acidbase ? conjugate baseconjugate
acid. The conjugate base is the ion or molecule
remaining after the acid has lost a proton, and
the conjugate acid is the species created when
the base accepts the proton. The reaction can
proceed in either forward or backward direction
in each case, the acid donates a proton to the
base.
6Bronsted-Lowry Base
Substance with the ability to gain, or "accept,"
a hydrogen cation (proton, H).
7Properties of Acids
- Acids taste sour
- Acids have a pH lower than 7
- Acids effect indicators
- Blue litmus turns red
- Universal indicator turns red
- Acids are proton (hydrogen ion, H) donors
- Acids react with active metals, produce H2
- Acids react with carbonates
- Acids neutralize bases
8Acids Have a pH less than 7
9Acids React with Active Metals
Acids react with active metals to form salts and
hydrogen gas.
Mg 2HCl ? MgCl2 H2(g)
10Acids Neutralize Bases
HCl NaOH ? NaCl H2O
Neutralization reactions ALWAYS produce a salt
and water.
11Acids you must know
Strong Acids
Weak Acids
Sulfuric acid, H2SO4
Phosphoric acid, H3PO4
Hydrochloric acid, HCl
Acetic acid, HC2H3O2
Nitric acid, HNO3
12Sulfuric Acid
- Highest volume production of any chemical in the
U.S. - Used in the production of paper
- Used in production of fertilizers
- Used in petroleum refining
13Nitric Acid
- Used in the production of fertilizers
- Used in the production of explosives
- Nitric acid is a volatile acid its reactive
components evaporate easily - Stains proteins (including skin!)
14Hydrochloric Acid
- Used in the pickling of steel
- Used to purify magnesium from sea water
- Part of gastric juice, it aids in the digestion
of protein - Sold commercially as Muriatic acid
15Phosphoric Acid
- A flavoring agent in sodas
- Used in the manufacture of detergents
- Used in the manufacture of fertilizers
- Not a common laboratory reagent
16Acetic Acid
- Used in the manufacture of plastics
- Used in making pharmaceuticals
- Acetic acid is the acid present in vinegar
17Acids are Proton Donors
Monoprotic acids
Diprotic acids
Triprotic acids
HCl
H2SO4
H3PO4
HC2H3O2
H2CO3
HNO3
18Ionization of HCl and formation of hydronium ion,
H3O
H2O HCl ?
H3O Cl-
Proton donor
Proton acceptor
19Strong Acids vs. Weak Acids
Strong acids are assumed to be 100 ionized in
solution (good proton donors).
HCl
H2SO4
HNO3
Weak acids are usually less than 5 ionized in
solution (poor proton donors).
H3PO4
HC2H3O2
Organic acids
20Strong Acid Dissociation
21Weak Acid Dissociation
22Effects of acid on the Environment
- Rainwater is naturally acidicWHY?When CO2 (gas)
H2O H2CO3 (aqueous) react they formCarbonic
acid Carbon dioxide (from the air) dissolves
inrainwater, producing carbonic acid, a weak
acid The normal pH of rainwater is about 5.6
23Effects of acid on the Environment
- Acid rain is rain with a pH less than 5.
-
- Forms when air-polluting gases dissolve in
- Rainwater
- Sulfur dioxide (SO2) Further lowers the pH of
rain.
24Effects of acid on the Environment
- Environmental Impact of Acid Rain
- Dependent on local geology
- Hill Country soil is rich in limestone (CaCO3),
which is basic - Limestone neutralizes the effect of acid rain on
lakes
25Damages Caused by Acid Rain1) Damage to aquatic
life
- In some sensitive lakes and streams,
acidification has completely eradicated - fish species, such as the brook trout, leaving
these bodies of water barren. Hundreds of the
lakes in the Adirondacks have acidity levels
unsuitable for the survival of fish
26Damages Caused by Acid Rain (Cont.)2.) Damage to
vegetation
27Damages Caused by Acid Rain (Cont.)3) Damage to
outdoor artwork (monuments statues)
28Properties of Bases
- Bases taste bitter
- Bases have a pH greater than 7
- Bases effect indicators
- Red litmus turns blue
- Universal indicator turns blue
- Phenolphthalein turns purple
- Bases are proton (H) acceptors
- and usually have hydroxide ions- OH-
- Solutions of bases feel slippery
- Bases neutralize acids
29Examples of Bases
- Sodium hydroxide (lye), NaOH
- Potassium hydroxide, KOH
- Magnesium hydroxide, Mg(OH)2
- Calcium hydroxide (lime), Ca(OH)2
30Bases Effect Indicators
Red litmus paper turns blue in contact with a
base.
Phenolphthalein turns purple in a base.
31Bases have a pH greater than 7
32Bases Neutralize Acids
Milk of Magnesia contains magnesium hydroxide,
Mg(OH)2, which neutralizes stomach acid, HCl.
2 HCl Mg(OH)2
MgCl2 2 H2O
33Products of Neutralization
HCl NaOH ?
NaCl H2O
H2SO4 Ca(OH)2 ?
CaSO4 2 H2O
HNO3 KOH ?
KNO3 H2O
The products of neutralization are always a
______ and _______.
salt
water