Slide 22 picture of Arrhenius and reception to

Slide 22: picture of Arrhenius and reception to work added Slide 25: space added between ref and 1 and 2 Slide 32: fixed subscript Slide 40: added strong and weak acid labels

Intersection 10: Acids and Bases 11/7/06 Reading: 16. 1 (p 765 -770) 16. 3 -16. 7 (p 773 -794)

Outline • Equilibrium wrap up • Acids and Bases – History – Models – Modern production – Dissociation

Equilibrium 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 concentrations dynamic rates completion Keq Where does the “equal” in equilibrium come from?

Equilibrium is Everywhere • Iodine thermometer Pictures from: jchemed. chem. wisc. edu/. . . / 2003/Aug/abs 878_1. html

Equilibrium is Everywhere 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. php 3? story_id=1377 What happens when salt is added to snowy winter roads?

Question 1 Apatite, Ca 5(PO 4)3 OH is the mineral in teeth. Ca 5(PO 4)3 OH(s) 5 Ca+2(aq) + 3 PO 4 -4(aq) + OH-(aq) On a chemical basis explain why drinking milk strengthens young children's teeth.

Muddiest Point from last week Q ? ? If you have the following equilibrium H 2 + I 2 2 HI Keq = 25 If you have 1 mol H 2, 2 mol I 2 and 3 mol HI, will you make more H 2 or HI?

Question 2 Cr. O 4 -2(aq) + 2 H+(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/fun 3_en/ acids/acids. htm

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

2000 Top 20 Chemicals Produced in US* Chemical 109 kg 1. Sulfuric acid 39. 62 11. Nitric acid 7. 99 2. Ethylene 25. 15 12. Ammonium nitrate 7. 49 3. Lime 20. 12 13. urea 6. 96 4. Phosphoric acid 16. 16 14. Ethyl benzene 5. 91 5. Ammonia 15. 03 15. Styrene 5. 41 6. Propylene 14. 45 16. Hydrochloric acid 4. 34 7. Chlorine 12. 01 17. Ethylene oxide 3. 87 8. Sodium hydroxide 10. 99 18. Cueme 3. 74 9. Sodium carbonate 10. 21 19. Ammonium sulfate 2. 60 10. Ethylene chloride 9. 92 20. 1, 3 -butatdiene *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. 2. 01 http: //scifun. chem. wisc. edu/chemweek/Sulf&top/Sulf&Top. html

History of Acids and Alkalies nefertiti. iwebland. com/ timelines/topics/drink. htm www. catskillarchive. com/ dwellers/g. htm

…a Brief History 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.

…a Brief History 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).

…Glauber Mid-1600's Johann Rudolph Glauber Na. Cl + H 2 SO 4 HCl + Glauber’s salt Acid + base = salt + water “Liquor fixus (KOH or K 2 CO 3 solution) and spiritus acidus nitri (HNO 3) 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). ”

… All Acids and Alkali Theory 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 theory of Tachenius and Sylvius?

… Bolye 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. "

… Lemery 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.

Acids: Oxygen or Hydrogen? 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.

Dualistic Theory 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

Arrhenius Model (Ph. D 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: Na. OH Na+ + OH-

Acid Base Reactions HCl + Na. OH HNO 3 + KOH

+ H or Hydronium? H+ proton + H 2 O H 3 O+

Hydronium 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 1 2 3 4 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 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 wa. Briger Losung Z. Phys. Chem. 1 340 -364.

Bronsted-Lowry Model Edward Franklin (1905) : NH 4 Cl + Na. NH 2 Na. Cl + 2 NH 3 Thomas Martin Lowry in England 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.

Bronsted Lowry Practice HCl + Na. OH HNO 3 + KOH HCl + NH 3 Acid: proton donor; Base: proton acceptor; Conjugate acid; conjugate base

Acids and Bases: Comparing Definitions Arrhenius Bronsted Acid provider of H+ in water Proton donor Base provider of OH- in water Proton acceptor Proton transfer Neutralization Formation of water + + OH- H O H 2 Equation Limitations Water only HA + B BH + A Proton transfer

If baseballs were really “base”balls…. +

Measurement of Acids and Bases p. H = -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+ p. H = -log [H 3 O+] = -log[ 1. 0 M] = 0

p. H [H 3 O+] 0 1 M 8 1 x 10 -8 1 0. 1 9 1 x 10 -9 2 0. 01 10 1 x 10 -10 3 0. 001 11 1 x 10 -11 4 1 x 10 -4 12 1 x 10 -12 5 1 x 10 -5 13 1 x 10 -13 6 1 x 10 -6 14 1 x 10 -14 7 1 x 10 -7 How do you measure base [OH-]?

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 (Kw) of this reaction. • In water, the [H 3 O+] and [OH-] ions are always in equilibrium with water having an equilibrium constant (Kw) of 1 x 10 -14 • In pure water [H 3 O+] = [OH-] = 1 x 10 -7 M. What about the p. H?

p. OH = - log[OH-] Remember that a low p. H corresponds to a high concentration of H 3 O+ (acidic) solution. Therefore, a low p. OH corresponds to a high concentration of OH- (basic) solution. Kw = [H 3 O+]*[OH-] = 1 x 10 -14 -log ([H 3 O+]*[OH-]) = - log (1 x 10 -14) -log [H 3 O+] - log[OH-] = 14 p. H + p. OH = 14

p. H [H 3 O+] p. OH [OH-] battery acid, concentrated HF 0 1 M 14 1 x 10 -14 HCl secreted by stomach lining 1 0. 1 13 1 x 10 -13 lemon juice, gastric acid, vinegar 2 0. 01 12 1 x 10 -12 grapefruit, orange juice, soda 3 0. 001 11 1 x 10 -11 tomato juice, acid rain 4 1 x 10 -4 10 1 x 10 -10 soft drinking water, black coffee 5 1 x 10 -5 9 1 x 10 -9 urine, saliva 6 1 x 10 -6 8 1 x 10 -8 "pure water" 7 1 x 10 -7 sea water 8 1 x 10 -8 6 1 x 10 -6 baking soda 9 1 x 10 -9 5 1 x 10 -5 Great Salt Lake, milk of magnesia 10 1 x 10 -10 4 1 x 10 -4 ammonia solution 11 1 x 10 -11 3 1 x 10 -3 soapy water 12 1 x 10 -12 2 1 x 10 -2 bleaches, oven cleaner 13 1 x 10 -13 1 1 x 10 -1 liquid drain cleaner 14 1 x 10 -14 0 1

Can you explain the following? Acid p. H [H 3 O+] 0. 1 M HCl 1. 0 0. 1 M acetic acid CH 3 COOH 2. 9 1. 26 x 10 -3 0. 1 M nitric acid HNO 3 1. 0 0. 1 M nitrous acid HNO 2 2. 2 6. 3 x 10 -3 0. 1 M hypochlorous acid HOCl 4. 2 6. 3 x 10 -5

Another Equilibrium Constant Ka For the reaction HA(aq) + H 2 O(l) → A- (aq) + H 3 O+(aq) Ka = ([H 3 O+][A-]) / [HA] Find the Ka for 0. 1 M HNO 2 using the p. H = 2. 2

Vocabulary 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

Strong Acids Bases 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) + H 2 O(l) → H 3 O+(aq) + Cl-(aq) acid 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. HCl. O 2(aq) + H 2 O(l) H 3 O+(aq) + Cl. O 2 -(aq) acid conj base Ka = ([H 3 O+][Cl. O 2 -]) / [HCl. O 2]

Strong Bases 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. Na. OH(aq) + H 2 O(l) → OH-(aq) + Na+(aq) base 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 N(aq) + H 2 O(l) → (CH 3)3 NH+(aq) + OH-(aq) base conj. acid Kb = ([(CH 3)3 NH+][OH-]) / [(CH 3)3 N]

Strong Acid Weak Acid

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

Practice Trimethylamine (CH 3)3 N has a Kb of 6. 5 x 10 -5. Write out its chemical reaction with water: What is the [OH-] of a 0. 010 M solution of triethylamine? What is the p. OH? What is the p. H?

What kinds of hydrogen atoms (protons) are acidic? H-halogen (HF, HCl, HBr, HI) H 2 O H 2 S (Ka 1 = 8. 9 x 10 -8) Oxoacids (H-polyatomic ions) (H 2 CO 3, HNO 3, etc. ) HCN

Organic Acids RCOOH

Bases OH R 3 N

Collecting Samples 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!

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