11/7/06
Reading: 16.1 (p765-770) 16.3-16.7
(p773-794)

Please turn in your exams by noon on Tuesday, 11/14

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• Equilibrium wrap up
– From last week
– Two everyday examples
– Practice questions
• Acids and Bases
– History
– Models
– pH Scale
– Dissociation
– Identifying acids and bases

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What are the characteristics of an equilibrium reaction? Use each of the following words in a sentence that describes an equilibrium reaction: products and reactants dynamic completion concentrations rates
K eq
Where does the “equal” in equilibrium come from?

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Use
LeChâtelier's Principle to predict what you will see:
Fe(NO
3
)
3
+ KSCN ↔ Fe(SCN) +2 + KNO
3 red
D
H < 0

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CaCO
3
(s) ↔ CaO(s) + CO
2
(g)
ΔH > 0
Using each method, explain what will happen to the concentration of CO to the system?
2 if solid lime (CaO) is added

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• Iodine thermometer
Pictures from: jchemed.chem.wisc.edu/.../
2003/Aug/abs878_1.html

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Salting the roads
Is ice in equilibrium?
http://antoine.frostburg.edu/chem/s enese/101/solutions/faq/why-saltmelts-ice.shtml
Picture from: www.glrc.org/story. php3?story_id=1377
What happens when salt is added to snowy winter roads?

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Apatite, Ca
5
(PO
4
)
3
OH is the mineral in teeth.
Ca
5
(PO
4
)
3
OH(s) 5 Ca +2 (aq) + 3PO
4
-4 (aq) + OH (aq)
On a chemical basis explain why drinking milk strengthens young children's teeth.

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Given the following equilibrium
H
2
+ I
2

2 HI K eq
= 25
If you have 1 mol H
2
, 2 mol I
2
HI?
and 3 mol HI in a 1 L flask, will you make more H
2 or

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CrO
4
-2 (aq) + 2H + (aq) ↔ Cr
2
O
7
-2 (aq) + H
2
O(l)
Explain what will happen to the equilibrium if water is added to this system?

From: www.funsci.com/fun3_en/ acids/acids.htm

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What do you know about acids and bases?
What makes something acidic/basic?
Who can name the most?

A 2000 Top 20 Chemicals Produced in US*
Chemical 10 9 kg 10 9 kg
1. Sulfuric acid 39.62
11. Nitric acid
2. Ethylene 25.15
7.99
12. Ammonium nitrate 7.49
3. Lime
4. Phosphoric acid
20.12
16.16
13. urea
14. Ethyl benzene
5. Ammonia 15.03
15. Styrene
6.96
5.91
5.41
4.34
6. Propylene 14.45
16. Hydrochloric acid
7. Chlorine
8. Sodium hydroxide
12.01
17. Ethylene oxide
10.99
18. Cueme
3.87
3.74
9. Sodium carbonate
10. Ethylene chloride
10.21
19. Ammonium sulfate
9.92
20. 1,3-butatdiene
2.60
2.01
http://scifun.chem.wisc.edu/chemweek/Sulf&top/Sulf&Top.html
*It does not include minerals which do not require processing, such as salt and sulfur, and petrochemical feedstocks, such as ethane and butane, which are considered products of oil companies.

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nefertiti.iwebland.com/ timelines/topics/drink.htm
www.catskillarchive.com/ dwellers/g.htm

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The only acid know to the ancient Egyptians,
Greeks, and Romans was______? It was made by air oxidation of fermented fruit juice (wine)
Among the alkalies known to the ancients were potash (potassium carbonate) obtained from____, soda (sodium carbonate) made by evaporation of alkaline waters, and lime (calcium oxide) made by roasting________. Caustic potash and caustic soda
(potassium and sodium hydroxides) were made by the action of lime on soda and potash.
Kauffman, G. B. "The Bronsted-Lowry Acid-Base Concept" J. Chem Ed. 1988, 65, 2831.

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Later, during the middle ages, the alchemists learned to make aqua frotis (nitric acid), aqua regia (a nitric-hydrochloric acid mixture), and oil of vitriol (sulfuric acid).

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Mid-1600's Johann Rudolph Glauber
2 NaCl + H
2
SO
4
 2 HCl + Glauber’s salt (Na
2
SO
4
)
Acid + base = salt + water
KOH + HNO
3

KNO
3
+ H
2
O
“Liquor fixus (KOH or K nitri (HNO
3
2
CO
3 solution) and spiritus acidus
) are in their nature…totally unlike, foes and adversaries of each other…and when the two are brought together…and the one part has overcome and killed the other, neither a fiery liquor nor a spiritus acidus can be found in their dead bodies, but the same has been made, as both were before and from which they were derived namely ordinary saltpeter (KNO
3
).”

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Otto Tachenius and Francois Sylvius tried to simplify the chemistry of life processes by reducing all chemical interactions within the living organism to acid-base reactions.
What evidence can you think of to support or discredit the theory of Tachenius and
Sylvius?

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Boyle (1663) noted that acids, in addition to their sour taste, had exceptional solvent power, the ability to color certain blue vegetable dyes red, and a precipitating action on dissolved sulfur.
Alkalies, on the other hand, had a slippery feel and detergent properties, the ability to dissolve oils and sulfur, and the capacity to counteract acids and destroy their properties. Boyle's tests showed that some substances were neutral and did not classify either as acids or alkalies."

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Nicholas Lemery (1675) described acids as having sharp spiky atoms, which produced a pricking sensation on the skin, and alkalies as being made up of round particles, which made them feel slippery or soapy.
When acids and bases were mixed, he pictured the sharp needles of the acids as penetrating the porous alkali globules, thus producing salts, which were neither stinging nor slippery to the touch.

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Antoine Lavoisier named the gaseous element oxygen in 1777. When sulfur or phosphorus was burned in oxygen, the products dissolved in water to form acids, so he concluded that oxygen was the element common to all acid materials.
Claude Louis Berthollet (1789) showed that prussic acid (HCN) did not contain oxygen
Humphry Davy proved Lavoisier's error more convincingly with muriatic acid (HCl), a very strong acid.

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Following the development of the battery by Alessandro
Volta (1800), chemists began to use this new device to decompose all kinds of substances. Jons Jacob
Berzelius and William Hisinger (1803) found that when salt solutions were subjected to electrolysis, bases were found at the negative pole and acids at the positive pole. They interpreted this to mean that acids and bases must carry opposite electrical charges.
Berzelius concluded that acid-base reactions were simply the result of electrical attractions. His dualistic theory
(1812) explained all chemical interactions in terms of neutralization of opposite electrical charges

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(PhD describing this work received lowest possible rating from his University)
Svante August Arrhenius, during his study of electrochemistry, observed that solutions of salts, acids, and bases were the only liquids that would conduct an electric current. He suggested (1884) that when these compounds dissolved in water they dissociated into charged particles, which he called "ions."
According to the Arrhenius theory acids are compounds that produce hydrogen ions in water solution: HCl

H + + Cl and bases are substances that provide hydroxide ions in water solution: NaOH

Na + + OH -

A
+
HCl
(aq)
H +
(aq)
(proton) + Cl -
(aq)
H
2
O
H
3
O +
(aq)
(hydronium)

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1
2
3
4
H
3
O + (H
2
O)
6 ref 1
H
3
O + (H
2
O)
20 ref 2
H
9
O
4
+ ref 3
H
5
O
2
+ ref 4
Figures: http://itl.chem.ufl.edu/2045/lectures/lec_x.html
http://cwx.prenhall.com/petrucci/medialib/media_portfolio/17.html
Zavitsas, A.A. (2001) Properties of water solutions of electrolyes and nonelectrolytes J. Phys. Chem. B 105
7805-7815.
Hulthe, G.; Stenhagen, G.; Wennstrom, O.; Ottosson, C.H. (1997) Water cluster studied by electrospray mass spectroscopy. J. Chromatogr. A 512 155-165.
Zundel, G.; Metzger, H. (1968) Energiebander der tunnelnden Ubershub-Protenon in flussigen Sauren. Eine
IR-spektrokpische Untersuchung der Natur der Gruppierungen H
5
O
2
+ Z. Phys. Chem. 58 225-245.
Wicke, E.; Eigen, M. Ackermann, Th. (1954) Uber den Zustand des Protons (Hydroniumions) in waBriger
Losung Z. Phys. Chem. 1 340-364.

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HCl
(aq)
+ NaOH
(aq)

H
2
O
(l)
+ NaCl
(aq)
HNO
3 (aq)
+ KOH
(aq)

H
2
O
(l)
+ KNO
3 (aq)

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Edward Franklin (1905) :
NH
4
Cl + NaNH
2

NaCl + 2 NH
3
Thomas Martin Lowry in England and
Johannes Nicholas Bronsted in Denmark
(1923) independently arrived at a more inclusive definition of the neutralization reaction as the transfer of a hydrogen ion
(a proton) from an acid to a base
.

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HCl
(aq)
+ NaOH
(aq)

H
2
O
(l)
+ NaCl
(aq)
HNO
3 (aq)
+ KOH
(aq)

H
2
O
(l)
+ KNO
3 (aq)
HCl + NH
3

NH
4
Cl
Acid: proton donor; Base: proton acceptor;
Conjugate acid; conjugate base

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Acid
Base
Arrhenius provider of H + in water
Bronsted proton donor provider of OH in water proton acceptor
Neutralization formation of water proton transfer
Equation H + + OH -

H
2
O HA + B

BH + A
Limitations water only proton transfer

If baseballs were really “base”balls….
+

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pH = -log[H
3
O + ]
HCl + H
2
O → H
3
O + + Cl -
A 1.0 M solution of HCl would produce 1.0 M H
3
O + pH = -log [H
3
O + ]
= -log[ 1.0M]
= 0

M
5
6
3
4
7 pH
0
1
2
[H
3
O + ] pH
1 M 8
0.1
9
0.01
10
0.001
11
1x10 -4 12
1x10 -5 13
1x10 -6 14
1x10 -7
How do you measure base [OH ]?
[H
3
O + ]
1x10 -8
1x10 -9
1x10 -10
1x10 -11
1x10 -12
1x10 -13
1x10 -14

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Water undergoes an equilibrium process called autoionization.
2 H
2
O
(l)
→ H
3
O +
(aq)
+ OH -
(aq)
• Write out the expression for the equilibrium constant (K w of this reaction.
)
• In water, the [H
3
O + ] and [OH ] ions are always in equilibrium with water having an equilibrium constant
(K w
) of 1x10 -14
• In pure water [H
3 pH?
O+] = [OH-] = 1x10 -7 M. What about the

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pOH = - log[OH ]
Remember that a low pH corresponds to a high concentration of H
3
O + (acidic) solution. Therefore, a low pOH corresponds to a high concentration of
OH (basic) solution.
K w
= [H
3
O + ]*[OH ] = 1 x10 -14
-log ([H
3
O + ]*[OH ]) = - log (1 x10 -14 )
-log [H
3
O + ] - log[OH ] = 14 pH + pOH = 14

M battery acid, concentrated HF
HCl secreted by stomach lining lemon juice, gastric acid, vinegar 2 grapefruit, orange juice, soda 3 pH
0
1 tomato juice, acid rain 4 soft drinking water, black coffee 5 urine, saliva 6
"pure water" sea water
7
8 baking soda 9
Great Salt Lake, milk of magnesia 10 ammonia solution soapy water
11
12 bleaches, oven cleaner liquid drain cleaner
13
14
[H
3
O + ] pOH
1 M 14
0.1
13
0.01
12
0.001
1x10 -4
1x10 -5
1x10 -6
11
10
9
8
1x10 -7
1x10 -8
7
6
1x10 -9 5
1x10 -10 4
1x10 -11 3
1x10 -12 2
1x10 -13 1
1x10 -14 0
[OH ]
1x10 -14
1x10 -13
1x10 -12
1x10 -11
1x10 -10
1x10 -9
1x10 -8
1x10 -7
1x10 -6
1x10 -5
1x10 -4
1x10 -3
1x10 -2
1x10 -1
1

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Acid
0.1 M HCl pH [H
3
O + ]
1.0
0.1 M
0.1 M acetic acid CH
3
COOH 2.9
1.26x10
-3
0.1 M nitric acid HNO
3
1.0
0.1 M
0.1 M nitrous acid HNO
2
2.2
6.3 x10 -3
0.1 M hypochlorous acid HOCl 4.2
6.3 x10 -5

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HA
(aq)
+ H
2
O
(l)
→ A -
(aq)
+ H
3
O +
(aq)
What is the expression for the equilibrium constant?
K a
= ([H
3
O + ][A ])
[HA]
Find the K a if a 0.1 M HNO
2 measures a pH = 2.2

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Strong (16 definitions): ionizing freely in solution
Weak (10 definitions): ionizing only slightly in solution
Favorable reaction..
Strong Reaction goes to completion exothermic spontaneous product favored

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An acid that dissociates completely (the equilibrium is shifted all of the way to its conjugate base and hydronium ion) is said to be a strong acid .
HCl
(aq) acid
+ H
2
O
(l)
→ H
3
O +
(aq)
+ Cl -
(aq) conj. base
An acid that does not dissociate completely (an equilibrium is established in solution between the acid, its conjugate base, and hydronium ion) is said to be a weak acid .
HClO acid
2(aq)
+ H
2
O
(l)
↔ H
3
O +
(aq)
+ ClO
2
conj base
(aq)
K a
= ([H
3
O + ][ClO
2
]) / [HClO
2
]

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A base that dissociates completely (the equilibrium is shifted all of the way to its conjugate acid and hydroxide) is said to be a strong base .
NaOH base
(aq)
+ H
2
O
(l)
→ OH -
(aq)
+ Na +
(aq) conj. acid
A base that does not dissociate completely (an equilibrium is established in solution between the base, its conjugate acid, and hydroxide) is said to be a weak base .
(CH
3
)
3 base
N
(aq)
+ H
2
O
(l)
↔ (CH
3
)
3
NH +
(aq) conj. acid
+ OH -
(aq)
K b
= ([(CH
3
)
3
NH + ][OH ]) / [(CH
3
)
3
N]

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Strong Acid
Weak Acid

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There are six strongly dissociating acids :
HCl HNO
3
HBr HClO
4
HI H
2
SO
4
There are also five bases that dissociate completely in solution (strong):
LiOH Ca(OH)
2
NaOH Ba(OH)
2
KOH
You should commit the strong acids and bases to memory.
Appendix F in your text book lists K a and K b values for many weakly dissociating acids and bases.

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Trimethylamine (CH
3
)
3
N has a K b of 6.5 x10
Write out its chemical reaction with water:
-5 .
What is the [OH ] of a 0.010 M solution of triethylamine?
What is the pOH?
What is the pH?

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H-halogen (HF, HCl, HBr, HI)
H
2
O
H
2
S (K a1
= 8.9x10
-8 )
Oxoacids (H-polyatomic ions) (H
2
CO
3
, HNO
3
, etc.)
HCN
O
H OH
O
C C
C
HO C
OH
H OH

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R
O
C
RCOOH
+ H
2
O
OH
R
O
C
O
-
+ H
3
O
+
R
O
-
C
O

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OH
R
3
N
H
2
N
O
CH C
CH
3
OH
H
2
N
O
CH C
CH
2
CH
2
C O
OH
OH
HN
O
C
OH

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Obtain Whirl pack bags
How do you fill the bags?
How many samples should you take?
How to store samples?
Filter (acid wash all glassware)
You may need special sampling techniques!

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• Field blank
– Controls for contamination during travel
• Lab Blank
– Controls for contamination during analysis