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Understanding Acids and Bases: Properties and Reactions

This article covers the properties of acids and bases, how they taste, react with other substances, and their role in nature and our bodies. It also includes thermochemical equations and the Arrhenius model.

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Understanding Acids and Bases: Properties and Reactions

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  1. Acids & Bases I. Properties of Acids & Bases -_____ taste ____ and produce a _______ sensation to the touch acids sour burning -______ acid and ________ acid, (also known as _______ __), are _____ _____ responsible for the _______ of ______ and other ______, while ______ ____ makes _______ taste ____, and in our body, the unpleasant ________ and _______ _________ produced by our _____ is due to ___________ ____ in our ________ citric ascorbic Vitamin C weak acids tartness citrus fruits acetic acid vinegar sour sourness Hydrangea – the color varies depending on the relative acidity or basicity of the soil burning sensation vomit hydrochloric acid stomach

  2. Acids & Bases I. Properties of Acids & Bases -because _____ ____ and _______ ________, (and all ______ ______ are made of _______), in ______, they are often used as a _______ acids burn denature proteins living things proteins nature defense -____, ____, ______, and ______ all use ______ ____ to ______ themselves, while the human _______ is guarded against _______ by ___________ ____, the human ______ is guarded against _______ by ______ ____ (produced by _____- _________ _______ of the genus ___________), and even human ____ is guarded by ____ ____ in our _____ bees ants nettles onions formic acid defend stomach bacteria hydrochloric acid vagina bacteria lactic acid sugar fermenting bacteria Lactobacillus skin uric acid sweat Stinging Nettle

  3. Acids & Bases I. Properties of Acids & Bases -_____ react with ______, especially the more ______ ______, to produce ________ ___ acids metals active metals hydrogen gas 1Zn (s) + 2HCl (aq) 1ZnCl2 (aq) + 1H2 (g) 2Al (s) + 6HNO3 (aq) 2Al(NO3)3 (aq) + 3H2 (g) acids carbonates -_____ react with _________ and ________ _________ to produce ______ _______ hydrogen carbonates carbon dioxide They don’t just taste “chalky”, they are chalk! 1CaCO3(s) + 2HCl (aq) 1CaCl2 (aq) + 1H2O (l) + 1CO2 (g) 1NaHCO3(s) + HC2H3O2 (aq) 1NaC2H3O2 (aq) + 1H2O (l) + 1CO2 (g)

  4. Acids & Bases I. Properties of Acids & Bases Write the balanced thermochemical equation for the reaction that occurs between: 1. Magnesium and Nitric acid 1Mg (s) + 2HNO3 (aq) 1Mg(NO3)2 (aq) + 1H2 (g) 2. Aluminum and Sulfuric acid 2Al (s) + 3H2SO4 (aq) 1Al2(SO4)3 (aq) + 3H2 (g) 3. Calcium carbonate and Hydrobromic acid 1CaCO3(s) + 2HBr (aq) 1CaBr2 (aq) + 1H2O (l) + 1CO2 (g) 4. Potassium Hydrogen carbonate and Hydrochloric acid 1KHCO3(s) + 1HCl (aq) 1KCl (aq) + 1H2O (l) + 1CO2 (g)

  5. Acids & Bases I. Properties of Acids & Bases 1. Hypothesis: Which common household materials are acids or bases? 2. Prediction: 3. Gather Data: A. Safety: The acids and bases used in this lab are mildly corrosive and cause irritation of the skin, eyes, and mucous membranes. Avoid contact. Use caution. Goggles mandatory. B. Procedure: 1. Using a pipette, place 3 or 4 drops of each solution in a separate test well of a microplate.

  6. Acids & Bases I. Properties of Acids & Bases 3. Gather Data: B. Procedure: 2. Test each liquid with litmus paper. Record results. 3. Test each liquid with 2 drops of phenolphthalein. Record results.

  7. Acids & Bases II. Ions in Solutions of Acids & Bases -the relative amounts of ____ and ____ ions in ________ _______ determine the _______ ______, _______, or ________ of the ________ H+ OH- aqueous solution relative acidity basicity neutrality solution aqueous solution -an _______ _______ that contains more ___ than ____ is an ______ _______ H+ OH- acidic solution Red tulip changes color in varying pH aqueous solution -an _______ _______ that contains more ____ than ___ is an _____ _______ OH- H+ basic solution -an _______ _______ that contains _____ amounts of ___ and ____ is _______ aqueous solution equal Purple iris changes color in varying pH H+ OH- neutral http://bradley.bradley.edu/~campbell/demopix5.html

  8. Acids & Bases II. Ions in Solutions of Acids & Bases -_______ ________ that are neither ______ or _____ are _______, but _____ is _______ because it is ____ an ____ and a ____ at the same time, containing _____ amounts of ___ and ____ aqueous solutions acids bases neutral water neutral both acid base equal H+ OH- polarity -because of its _______, _____ ___________: Purple carnation changes color in varying pH water self-ionizes 1H2O(l) 1H+ (aq) + 1OH-(aq) H+ covalent -but the ___ forms a _______ _____ with a ______ _____ ________, producing the __________ ____ bond another water molecule hydronium ion Peony changes color in varying pH 2H2O(l) 1H3O+(aq) + 1OH-(aq) http://bradley.bradley.edu/~campbell/demopix5.html

  9. Acids & Bases III. The Arrhenius Model of Acids and Bases -according to ______ _________, an ____ is a ________ that contains ________ and _______ to produce ________ ____ in _______ _______ Svante Arrhenius acid substance hydrogen ionizes hydrogen ions aqueous solution -according to _________, ________ ________ is an _____ Arrhenius Hydrogen chloride acid 1HCl (g) 1H+ (aq) + 1Cl- (aq) -according to _________, a _____ is a ________ that contains a _________ _____ and _________ to produce _________ _____ in _______ ________ Arrhenius base substance hydroxide group dissociates hydroxide ions aqueous solution -according to _________, ________ _________ is a _____ Arrhenius Sodium hydroxide base 1NaOH (s) 1Na+ (aq) + 1OH- (aq) Svante August Arrhenius 1859 - 1927

  10. Acids & Bases IV. The Brønsted –Lowry Model of Acids and Bases -according to ________-______, an _____ is a _________-____ ______ and a _____ is a ________- ____ ________ Brønsted Lowry acid hydrogen ion donor base hydrogen ion acceptor 1HX (aq) + 1H2O (l) 1H3O+(aq) + 1X- (aq) Base Acid Conjugate Acid Conjugate Base -the _____, ______, _________ in _____ and _______ a ________ ____ to a ______ ________, which acts as a _____ by ________ the ________ ____ acid HX (aq) dissolves water donates hydrogen ion water molecule base accepting hydrogen ion base accepted H+ -a ____ that has ________ a ___ now has the ability to ______ a ___, and so becomes an _____; the _________ _____ donate H+ acid Johannes Nicolaus Brønsted 1879 - 1947 Thomas Martin Lowry 1874 - 1936 conjugate acid

  11. Acids & Bases IV. The Brønsted –Lowry Model of Acids and Bases -according to ________-______, a _________ ____ is the ______ produced when a ____ accepts a ________ ___ from an ____ Brønsted Lowry conjugate acid species base hydrogen ion acid 1HF (aq) + 1H2O (l) 1H3O+(aq) + 1F- (aq) Base Acid Conjugate Acid Conjugate Base -a _________ ____ is the ______ that is left over from the ____ after it donates a ________ ____ conjugate base species acid hydrogen ion How is playing Hacky Sack Like Conjugate Acid-Base Pairs? Player who passed Footbag Conjugate acid Player passing Footbag Acid Footbag Hydrogen ion Player receiving Footbag Base Playing Hacky Sack in Zurich, Switzerland Player who received Footbag Conjugate base http://zurichdailyphoto.blogspot.com/2007/04/hacky-sack.html

  12. Acids & Bases IV. The Brønsted –Lowry Model of Acids and Bases Label the acid, base, conjugate acid, and conjugate base in the following: 1NH3(aq) + 1H2O (l) 1NH4+(aq) + 1OH- (aq) Substances that can act as both an acid and a base are called amphoteric, as water is in these examples. Base Acid Conjugate Acid Conjugate Base 1HBr (aq) + 1H2O (l) 1H3O+(aq) + 1Br- (aq) Acid Base Conjugate Acid Conjugate Base 1CO32-(aq) + 1H2O (l) 1HCO3-(aq) + 1OH- (aq) Conjugate Acid Conjugate Base Base Acid 1HSO4-(aq) + 1H2O (l) 1H3O+(aq) + 1SO42- (aq) Acid Base Conjugate Acid Conjugate Base

  13. Acids & Bases H O H C C O H H V. Monoprotic & Polyprotic Acids -____ and ___ are _____ according to the _________ _____ because they both contain _________ and they both donate a ________ ___ to an _______ ________ HCl HF acids Arrhenius model hydrogen hydrogen ion aqueous solution HCl HF -both ____ and ___ are also __________ _____ because each donates only ____ _________ ___ per ________ monoprotic acids Chemical burns caused by Hydrofluoric acid one http://www.emedicine.com/emerg/topic804.htm hydrogen ion molecule -_____ (______ _____), ______ (_________ _____), ____ (____________ _____), and _________ (______ or ________ _____) are other __________ ______ HNO3 Nitric acid HClO4 Perchloric acid HBr Hydrobromic acid CH3COOH acetic Even though acetic acid has 4 hydrogen atoms, only 1 of the 4 has a polar enough bond to be ionizable. The other 3 are practically nonpolar bonds. ethanoic acid monoprotic acids

  14. Acids & Bases H C H H C C C C H C H H H O O O S O O P O H H O O H H V. Monoprotic & Polyprotic Acids -_____ that donate _____ than ____ _________ ___ are called _________ acids more one hydrogen ion polyprotic -______(_______ _____) and ______(________ _____) are both _______ _____, while ______ (__________ ____) and ______ (______ _____) are both _________ ______ H2SO4 Sulfuric acid H2CO3 Carbonic acid diprotic acids H3PO4 Phosphoric acid H3BO3 Boric acid triprotic acids Benzene has 6 hydrogen atoms, but none of the covalent bonds are polar enough to be ionizable, so benzene is not an acid at all. Sulfuric acid contains 2 highly polar ionizable covalent bonds Phosphoric acid contains 3 highly polar ionizable covalent bonds

  15. Acids & Bases H O O P O H O H V. Monoprotic & Polyprotic Acids -__________ _____ donate more than ____ ________ ____ to _______ _______ in more than ___ step polyprotic acids one hydrogen ion aqueous solution one -the ________ ____ __________ ____ donates __ ________ ____ in __ steps: triprotic acid Phosphoric acid 3 hydrogen ions 3 1H3PO4(aq) + 1H2O (l) 1H3O+(aq) + 1H2PO4- (aq) 1H2PO4-(aq) + 1H2O (l) 1H3O+(aq) + 1HPO42- (aq) 1HPO42-(aq) + 1H2O (l) 1H3O+(aq) + 1PO43- (aq)

  16. Acids & Bases V. Monoprotic & Polyprotic Acids Write the steps for complete ionization of the following polyprotic acids: H2Se (aq) + H2O (l) H3O+(aq) + 1HSe- (aq) HSe-(aq) + H2O (l) H3O+(aq) + Se2- (aq) H3AsO4 (aq) + H2O (l) H3O+(aq) + H2AsO4- (aq) H2AsO4-(aq) + H2O (l) H3O+(aq) + HAsO42- (aq) HAsO42-(aq) + H2O (l) H3O+(aq) + AsO43- (aq) H2SO3 (aq) + H2O (l) H3O+(aq) + HSO31- (aq) HSO31-(aq) + H2O (l) H3O+(aq) + SO32- (aq)

  17. Acids & Bases VI. Acid & Base Anhydrides -__________ are _______ that form _____ and _____ when added to ______ anhydrides oxides acids bases water 1CO2(g) + 1H2O (l) 1H2CO3 (aq) 2NO2(g) + 1H2O (l) 1HNO3 (aq) + 1HNO2 (aq) 1SO2(g) + 1H2O (l) 1H2SO3 (aq) 1SO3(g) + 1H2O (l) 1H2SO4 (aq) oxides nonmetallic -______ of ___________ elements produce _____ in _______ _______, while ______ of ________ elements produce _____ in _______ ________ acids aqueous solution oxides metallic bases aqueous solution 1CaO (s) + 1H2O (l) 1Ca2+ (aq) + 2OH- (aq) 1MgO (s) + 1H2O (l) 1Mg2+ (aq) + 2OH- (aq)

  18. Acids & Bases VII. Strength of Acids -______ _____ are _____ that ______ _________ strong acids acids ionize completely 1HCl (aq) + 1H2O (l) 1H3O+ (aq) + 1Cl- (aq) -____ (___________ _____), ______ (__________ _____), _____ (______ ____), ____ (____________ _____), ______ (________ _____), and ___ (___________ _____) are all ______ _____ HCl Hydrochloric acid HClO4 Hydrofluoric acid is considered a weak acid because it doesn’t ionize completely; it is expected to be a strong acid, because it is so corrosive, but its corrosiveness is due to the chemical reactivity of its anion, the fluoride ion. The strongest acids, the carborane superacids, are a million times stronger than concentrated sulfuric acid, but not at all corrosive because the anion to the acid is so unreactive. Perchloric acid HNO3 Nitric acid HBr Hydrobromic acid H2SO4 Sulfuric acid HI Hydroiodic acid strong acids -______ _____ are _____ that ______ only ________ weak acids acids ionize partially HC2H3O2 (aq) + H2O (l) H3O+(aq) + C2H3O2- (aq) -________ (______ _____), ______ (________ _____), ___ (___________ ____), ______ (_____ _____), and _____ (___________ ____) are _____ _____ HC2H3O2 Acetic acid H2CO3 Carbonic acid HF Hydrofluoric acid H3BO3 Boric acid HCN Hydrocyanic acid weak acids

  19. Acids & Bases VII. Strength of Acids -according to ______________, the ____ on the _______ side of the ________ _______ produces a ________ ____ on the ________ side of the _______ _______ by _______ a ________ ___ Brønsted-Lowry acid reactant forward reaction conjugate base product forward reaction donating hydrogen ion 1HX (aq) + 1H2O (l) 1H3O+(aq) + 1X- (aq) Acid Conjugate Base -if the ____ is a ______ ____, then its _________ ____ is _____, that is, if the ____ readily _______ a ________ ___, then its ________ ____ is not very good at ________a ________ ___, or holding on to one, while a ____ ____, which is not very good at _______ a ________ ___ has a ______ ________ ____ acid strong acid conjugate base weak acid donates hydrogen ion conjugate base accepting hydrogen ion weak acid donating hydrogen ion strong conjugate base

  20. Acids & Bases VII. Strength of Acids -the _________ ________ for ___________ _____ is: ionization equation Hydrocyanic acid 1HCN (aq) + 1H2O (l) 1H3O+(aq) + 1CN- (aq) equilibrium constant expression -the __________ ________ __________ for the _________ of ____________ _____ is: ionization Hydrocyanic acid [H3O+]1 [CN-]1 Keq = [HCN]1 [H2O]1 concentration liquid water -the ___________ of ______ _____ is considered to be _______, and so can be _________ with ___ to give the _____ _________ _______, or ___ constant combined Keq acid ionization constant Ka [H3O+]1 [CN-]1 Ka = [HCN]1

  21. Acids & Bases VII. Strength of Acids Write ionization equations and acid ionization constant expressions for the following acids: HClO2(aq) + H2O (l) H3O+(aq) + ClO2- (aq) [H3O+]1 [ClO2-]1 Ka = [HClO2]1 HNO2(aq) + H2O (l) H3O+(aq) + NO2- (aq) [H3O+]1 [NO2-]1 Ka = [HNO2]1 HIO (aq) + H2O (l) H3O+(aq) + IO- (aq) [H3O+]1 [IO-]1 Ka = [HIO]1

  22. Acids & Bases VIII. Strength of Bases -______ _____ are _____ that _________ _________ strong bases bases dissociate completely 1NaOH (s) 1Na+ (aq) + 1OH- (aq) -______ (_______________), _____ (_________________), ______ (_________ _________), _____ (_______________), _______ (________________), and ______ (_______________) are all ______ _____ NaOH Sodium hydroxide KOH Potassium hydroxide RbOH Rubidium hydroxide CsOH Cesium hydroxide Ca(OH)2 Calcium hydroxide Ba(OH)2 Barium hydroxide strong bases -______ _____ are _____ that ________ only ________ weak bases bases dissociate partially CH3NH2 (aq) + H2O (l) CH3NH3+(aq) + OH- (aq) -________ (___________), ________ (__________), ____ (________), and ________ (______) are all _____ ______ CH3NH2 methylamine C2H5NH2 ethylamine NH3 ammonia C6H5NH2 aniline weak bases

  23. Acids & Bases H H H H H H H H C C C C C C N H H H H H H H VIII. Strength of Bases -the ________ ________ for __________ is: ionization equation hexylamine 1C6H13NH2(aq) + 1H2O (l) 1OH-(aq) + 1C6H13NH3+(aq) Conjugate Acid Conjugate Base Base Acid acid ionization constant -the ____ __________ ________ __________ for the _________ of ___________ is: expression ionization hexylamine [OH-]1 [C6H13NH3+]1 Kb = [C6H13NH2]1 Hexylamine

  24. Acids & Bases VIII. Strength of Bases Write ionization equations and base ionization constant expressions for the following bases: C3H7NH2(aq) + H2O (l) OH-(aq) + C3H7NH3+ (aq) [OH-]1 [C3H7NH3+]1 Kb = [C3H7NH2]1 CO32-(aq) + H2O (l) OH-(aq) + HCO3- (aq) [OH-]1 [HCO3-]1 Kb = [CO32-]1 HSO3-(aq) + H2O (l) OH-(aq) + H2SO3 (aq) [OH-]1 [H2SO3]1 Kb = [HSO3-]1

  25. Acids & Bases IX. Ion Product Constant for Water -the ________ ________ for ______ is: ionization equation water H2O (l) + H2O (l) OH-(aq) + H3O+ (aq) Conjugate Acid Conjugate Base Base Acid ionization equation -the ________ ________ can be simplified to: H2O (l) OH-(aq) + H+ (aq) equilibrium constant -the __________ _______ __________ is: expression [OH-]1 [H+]1 Keq = [H2O]1

  26. Acids & Bases IX. Ion Product Constant for Water -since _____ is a ______, its _____________ is equal to its _______, which is _______ at a _______ ___________ and ________, so the __________ _______ _________ can be simplified by __________ both sides by ______, creating the ___ _______ _______ ___ _____, ___ water liquid concentration density constant Kw = [OH-]1 [H+]1 constant temperature pressure equilibrium Kw = (1 x 10-7)1 (1 x 10-7)1 constant expression Kw = 1 x 10-14 multiplying [H2O] ion product constant for water Kw 298 K self ionization -at _____, the ____- _________ of _____ produces ____ = _________ and a ______ = _________, so ___ = _______ [H+] water [OH-] 1 x 10-7M Kw 1 x 10-7M 1 x 10-14

  27. Acids & Bases IX. Ion Product Constant for Water What is the concentration of the hydroxide ion in an aqueous solution with a hydrogen ion concentration of 1 x 10-5M? Is the solution acidic, basic, or neutral? Kw = [H+] [OH-] 1 x 10-14 = (1 x 10-5) [OH-] [OH-] = 1 x 10-9 M The solution is acidic, because the [H+] is greater (104) than the [OH-] What is the concentration of the hydrogen ion in an aqueous solution with a hydroxide ion concentration of 1 x 10-3M? Is the solution acidic, basic, or neutral? Kw = [H+] [OH-] 1 x 10-14 = [H+] (1 x 10-3) [H+] = 1 x 10-11 M The solution is basic, because the [OH-] is greater (108) than the [H+]

  28. Acids & Bases X. pH (pondus hydrogenii) -in 1909, _____ ________ developed the ___ (________ _________) _____ as a way of conveniently expressing the ___________ of _____ and _____ Søren Sørensen pH potential hydrogen scale concentration acids bases pH = -log [H+] What is the pH of water? The number of decimal places in the pH is equal to the number of significant digits in the [H+] pH = -log [H+] pH = -log (1 x 10-7) pH = 7.0 1 sig. fig. in [H+], 1 decimal place in pH What is the pH of an aqueous solution in which the [H+] = 1.0 x 10-2M? pH = -log [H+] pH = -log (1.0 x 10-2) pH = 2.00 2 sig. figs. in [H+], 2 decimal place in pH Søren Sørensen 1868 - 1939

  29. Acids & Bases X. pH (pondus hydrogenii) 1. Hypothesis: What is the relationship between the concentration of an acid and its pH? 2. Prediction: 3. Gather Data: A. Safety: The acids used in this lab are corrosive and cause irritation and damage to the skin, eyes, and mucous membranes. Avoid contact. Use caution. Goggles mandatory. B. Procedure: Serial Dilution 1. Using a pipette, place 10 drops of 1.0 M HCl in test well 1A of a microplate.

  30. Acids & Bases X. pH (pondus hydrogenii) 3. Gather Data: B. Procedure: 2. Rinse the pipette, and transfer 1 drop of acid solution from test well 1A to test well 2A, and add 9 drops of distilled water. 3. Repeat Step 2, transferring 1 drop of acid solution from test well 2A to test well 3A and adding 9 drops of distilled water . 4. Repeat Step 2 six more times, each time transferring 1 drop of acid solution from the previous test well and adding 9 drops of distilled water.

  31. Acids & Bases X. pH (pondus hydrogenii) 3. Gather Data: B. Procedure: 5. Test the pH in each well with pH indicator paper. Record. 6. Test the pH in each well with 1 drop of universal indicator solution. Record.

  32. Acids & Bases X. pH (pondus hydrogenii) 4. Analyze Data: A. What is [H+] in test well A4? ________________. B. What is [H+] in test well A6? ________________. C. What is the theoretical pH in test well A2? _______________. D. What is the theoretical pH in test well B2? _______________. E. The color of pH paper in test well A1 was _______, indicating an approximate pH of _______. F. In test well A2 universal indicator was ________ in color. 5. Draw Conclusions: A. Each step in the serial dilution ____________ the concentration of the hydrogen ion by a factor of _______ and __________ the pH by a factor of _______

  33. Acids & Bases XI. pOH (potential Hydroxide) -the _______, or ________, of a _______ can be expressed by the ____, or ________ _________: basicity alkalinity solution pOH potential Hydroxide pOH = -log [OH-] What is the pOH of water? What is the pH of an aqueous solution in which the [OH-] = 1.0 x 10-3M? pOH = -log [OH-] pOH = -log [OH-] pOH = -log (1 x 10-7) pOH = -log (1.0 x 10-3) pOH = 7.0 pOH = 3.00 What is the pOH of an aqueous solution in which the [OH-] = 1.00 x 10-6M? Kw = [OH-] [H+] pOH = -log [OH-] 1 x 10-14 = (1 x 10-7) (1 x 10-7) pOH = -log (1.00 x 10-6) 14 = pH + pOH pOH = 6.000 pH = 11.00

  34. Acids & Bases XI. pOH (potential Hydroxide) What is the pH and the pOH of an aqueous solution with a hydroxide ion concentration of 1.0 x 10-6M? Is the solution acidic, basic, or neutral? pOH = -log [OH-] pOH = 6.00 pH = 8.00 pOH = -log (1.0 x 10-6) 14 = pH + pOH basic What is the pH and the pOH of an aqueous solution with a hydroxide ion concentration of 6.5 x 10-4M? Is the solution acidic, basic, or neutral? pOH = -log (6.5 x 10-4) pH = 10.81 pOH = 3.19 basic What is the pH and the pOH of an aqueous solution with a hydrogen ion concentration of 3.6 x 10-9M? Is the solution acidic, basic, or neutral? pH = -log (3.6 x 10-9) pOH = 5.56 pH = 8.44 basic

  35. Acids & Bases XI. pOH (potential Hydroxide) What is the hydrogen ion concentration and the hydroxide ion concentration of a person’s blood that has a pH of 7.40 at 298 K? pH = -log [H+] [H+] = 4.0 x 10-8 M 6.60 = -log [OH-] 7.40 = -log [H+] 14 = 7.40 + pOH [OH-] = 2.5 x 10-7 M What is the hydrogen ion concentration and the hydroxide ion concentration of an aqueous solution that has a pH of 2.37 at 298 K? Multiply [H+][OH-] to check your answer 2.37 = -log [H+] 11.63 = -log [OH-] [H+] = 4.3 x 10-3 M [OH-] = 2.3 x 10-12 M Kw = (4.3 x 10-3) (2.3 x 10-12) What is the hydrogen ion concentration and the hydroxide ion concentration of an aqueous solution that has a pH of 11.05 at 298 K? Multiply [H+][OH-] to check your answer 11.05 = -log [H+] 2.95 = -log [OH-] [H+] = 8.9 x 10-12 M [OH-] = 1.1 x 10-3 M Kw = (8.9 x 10-12) (1.1 x 10-3)

  36. Acids & Bases XII. Calculating pH of Strong Acids and Strong Bases What is the pH of a 1.0 M HI solution? pH = -log [H+] 1HI (aq) 1H+ (aq) + 1I- (aq) pH = -log (1.0) pH = 0.00 1.0 M 1.0 M 1.0 M What is the pH of a 0.050 M HNO3 solution? pH = -log [H+] pH = -log (0.050) 1HNO3(aq) 1H+ (aq) + 1NO3- (aq) pH = 1.30 0.050 M 0.050 M 0.050 M What is the pOH of a 2.4 x 10-5M Mg(OH)2 solution? 1Mg(OH)2(s) 1Mg2+ (aq) + 2OH- (aq) pOH = -log [OH-] pOH = -log (4.8 x 10-5) 2.4 x 10-5M 2.4 x 10-5M 4.8 x 10-5M pOH = 4.32 pH = 9.68

  37. Acids & Bases XIII. Calculating pH of Weak Acids and Weak Bases What is Ka of a 0.100 M formic (methanoic) acid solution with pH 2.38? 1HCOOH (aq) 1HCOO-(aq) + 1H+ (aq) 0.100 M 4.2 x 10-3M 4.2 x 10-3M pH = -log [H+] [H+] = 4.2 x 10-3 M 2.38 = -log [H+] [HCOO-] = 4.2 x 10-3 M [HCOOH] = 0.100 M - 4.2 x 10-3 M [HCOOH] = 0.100 M - 0.0042M [HCOOH] = 0.096 M [HCOO-] [H+] (4.2 x 10-3 ) (4.2 x 10-3 ) Ka = Ka = [HCOOH] (0.096 ) Ka = 1.8 x 10-4

  38. Acids & Bases XIII. Calculating pH of Weak Acids and Weak Bases What is Ka of a 0.220 M arsenic acid solution with pH 1.50? 1H3AsO4(aq) 1H2AsO4-(aq) + 1H+ (aq) 0.220 M 3.2 x 10-2M 3.2 x 10-2M pH = -log [H+] [H+] = 3.2 x 10-2 M 1.50 = -log [H+] [H2AsO4-] = 3.2 x 10-2 M [H3AsO4] = 0.220 M - 3.2 x 10-2 M [H3AsO4] = 0.220 M - 0.032M [H3AsO4] = 0.188 M [H2AsO4-] [H+] (3.2 x 10-2 ) (3.2 x 10-2 ) Ka = Ka = [H3AsO4] (0.188 ) Ka = 5.4 x 10-3

  39. Acids & Bases XIII. Calculating pH of Weak Acids and Weak Bases What is Ka of a 0.0400 M chlorous acid solution with pH 1.80? 1HClO2(aq) 1ClO2-(aq) + 1H+ (aq) 0.0400 M 1.6 x 10-2M 1.6 x 10-2M pH = -log [H+] [H+] = 1.6 x 10-2 M 1.80 = -log [H+] [ClO2-] = 1.6 x 10-2 M [HClO2] = 0.0400 M - 1.6 x 10-2 M [HClO2] = 0.0400 M - 0.016M [HClO2] = 0.024 M [ClO2-] [H+] (1.6 x 10-2 ) (1.6 x 10-2 ) Ka = Ka = [HClO2] (0.024 ) Ka = 1.1 x 10-2

  40. Acids & Bases XIII. Calculating pH of Weak Acids and Weak Bases What is Ka of a 1.000 M propanoic acid solution with pH 2.43? 1HC3H5O2(aq) 1C3H5O2-(aq) + 1H+ (aq) 1.000 M 3.7 x 10-3M 3.7 x 10-3M pH = -log [H+] [H+] = 3.7 x 10-3 M 2.43 = -log [H+] [C3H5O2-] = 3.7 x 10-3 M [HC3H5O2] = 1.000 M - 3.7 x 10-3 M [HC3H5O2] = 1.000 M - 0.0037M [HC3H5O2] = 0.9963 M [C3H5O2-] [H+] (3.7 x 10-3 ) (3.7 x 10-3 ) Ka = Ka = [HC3H5O2] (0.9963 ) Ka = 1.4 x 10-5

  41. Acids & Bases XIV. Neutralization -when an ____ and a ____ _____, the resulting _______ has _________ that are characteristic of _______ an ____ or a ____ acid base react solution properties neither acid base neutralization reaction double -a ____________ _______ is a ______- ___________ _______ in which an ____ and a ____ react in _______ ________ to produce a ____ and _____ replacement reaction acid base aqueous solution salt water 1Mg(OH)2(aq) + 2HCl (aq) 1MgCl2 (aq) + 2H2O (l) base acid salt water Milk of Magnesia is a Magnesium hydroxide suspension used to neutralize stomach acid -a ____ is an _____ _________ made up of the ______ from the ____ and the _____ from the ____ salt ionic compound cation base anion acid net ionic equation neutralization -the ___ _____ ________ for a ____________ _______ is: reaction OH-(aq) + H+ (aq) H2O (l)

  42. Acids & Bases XIV. Neutralization Write the complete balanced thermochemical equations for the following neutralization reactions and name the products: Nitric acid + Cesium hydroxide 1HNO3 (aq) + 1CsOH (aq) 1CsNO3 (aq) + 1H2O (l) acid base Cesium nitrate water Hydrobromic acid + Calcium hydroxide 2HBr (aq) + 1Ca(OH)2(aq) 1CaBr2 (aq) + 2H2O (l) acid base Calcium bromide water Sulfuric acid + Potassium hydroxide 1H2SO4(aq) + 2KOH (aq) 1K2SO4 (aq) + 2H2O (l) acid base Potassium sulfate water

  43. Acids & Bases XV. Titration -a _______is a method for determining an ________ ____________ of a solution by _______ a ______ ______ of a _______ solution of ______ ____________ titration unknown concentration reacting known volume different known concentration -to find the ________ ___________ of a ______ ______ of ____ solution, you can ______ the solution with a ______ ______ of an ____ solution of ______ ____________ unknown concentration known volume base titrate known volume acid known concentration electronic pH meter 1HCl (aq) + 1NaOH (aq) 1NaCl (aq) + 1H2O (l) acid base salt water 1 L HCl sol. 1 mole HCl 1 mole NaOH 1 mL HCl sol. x ______________ x ___________ x _______________ = 0.001 mole NaOH 1000 mL HCl sol. 1 L HCl sol. 1 mole HCl 0.001 mole NaOH 1000 mL NaOH sol. M = _______________ x _______________ = 0.1 M NaOH 10 mL NaOH sol. 1 L NaOH sol.

  44. Acids & Bases XV. Titration What is the molarity of a CsOH solution if 30.0 mL of the solution is neutralized by 26.4 mL of 0.250 M HBr solution? 1HBr (aq) + 1CsOH (aq) 1CsBr (aq) + 1H2O (l) 1 L HBr sol. 0.250 mole HBr 1 mole CsOH 26.4 mL HBr sol. x ______________ x ___________ x _______________ = 0.00660 mole CsOH 1000 mL HBr sol. 1 L HBr sol. 1 mole HBr 0.00660 mole CsOH 1000 mL CsOH sol. M = _______________ x _______________ = 0.220 M CsOH 30.0 mL CsOH sol. 1 L CsOH sol. What is the molarity of a nitric acid solution if 20.00 mL of the solution is neutralized by 43.33 mL of 0.1000 M KOH solution? 1HNO3 (aq) + 1KOH (aq) 1KNO3 (aq) + 1H2O (l) 1 L KOH sol. 0.1000 mole KOH 1 mole HNO3 43.33 mL KOH sol. x ______________ x ______________ x _______________ = 4.333 x 10-3 mole HNO3 1000 mL KOH sol. 1 L KOH sol. 1 mole KOH 4.333 x 10-3 mole HNO3 1000 mL HNO3 sol. M = _______________ x _______________ = 0.2167 M HNO3 20.00 mL HNO3 sol. 1 L HNO3 sol.

  45. Acids & Bases XV. Titration -during the course of a _______, a known _______ of a _______ of known ___________ is added until the __________ _____ is reached, at which the _______ of ______ of ____ equals the _______ of ______ of _____ titration volume solution concentration equivalence point number moles H+ number moles OH- -corresponding closely with the __________ _____ is the ___ _____, at which the ________ changes _____ equivalence point end point indicator color Adding indicator Titrating End Point

  46. Acids & Bases H+ Adding an acid, raising [H+] OH- Adding a base, raising [OH-] XVI. Buffered Solutions -_______ are _________ that _____ changes in ___ buffers solutions resist pH buffer mixture weak acid -a ______ is a _______ of a _____ ____ and its _________ ____ conjugate base Weak acid Conjugate base HF (aq) H+ (aq) + F- (aq) Human blood is buffered by the weak acid carbonic acid (H2CO3) and its conjugate base, hydrogen carbonate (HCO3-) HF (aq) H+ (aq) + F- (aq) Equilibrium shifts to the left, lowering [H+] H2O (l) H+ (aq) + OH- (aq) H2O (l) H+ (aq) + OH- (aq) Equilibrium shifts to the left, lowering [OH-]

  47. Acids & Bases OH- Adding a base, raising [OH-] H+ Adding an acid, raising [H+] XVI. Buffered Solutions -a ______ can also be a _______ of a _____ ____ and its _________ ____ buffer mixture weak base conjugate acid Weak base Conjugate acid NH3 (aq) + H2O (l) NH4+ (aq) + OH- (aq) NH3 (aq) + H2O (l) NH4+ (aq) + OH- (aq) Equilibrium shifts to the left, lowering [OH-] H2O (l) H+ (aq) + OH- (aq) H2O (l) H+ (aq) + OH- (aq) Equilibrium shifts to the left, lowering [H+]

  48. Acids & Bases XVI. Buffered Solutions What is the pH of buffer system made by mixing equal amounts of H2PO4- and HPO42-? H2PO4-(aq) H+(aq) + HPO42- (aq) [H+] [HPO42-] Ka = [H2PO4-] [H+] [HPO42-] 6.2 x 10-8 = [H2PO4-] 6.2 x 10-8 = [H+] pH = -log (6.2 x 10-8) pH = 7.21

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