3. þ Produce H + (as H 3 O + ) ions in water (the hydronium ion is a hydrogen ion attached to a water molecule) þ Taste sour þ Corrode metals (react to  H 2 (g)) þ Are electrolytes (conduct electricity) þ React with bases to form a salt and water þ pH is less than 7 þ Turns blue litmus paper to red “Blue to Red A-CID”

4.  Produce OH - ions in water  Taste bitter, chalky  Are electrolytes (conduct electricity)  Feel soapy, slippery  React with acids to form salts and water  pH greater than 7  Turns red litmus paper to blue “Basic Blue”

5. HCl Hydrochloric AcidStomach acid HNO3 Nitric AcidJewelry making H2SO4Sulfuric AcidPaper making; Car batteries H3PO4Phosphoric AcidPreservative in Coca-Cola NaOHSodium hydroxidelye KOHPotassium hydroxideliquid soap Ba(OH) 2 Barium hydroxidestabilizer for plastics Mg(OH) 2 Magnesium hydroxide“MOM” Milk of magnesia Al(OH) 3 luminum hydroxideMaalox (antacid) Al(OH) 3 Aluminum hydroxideMaalox (antacid)

6. Definition #1: Arrhenius (traditional)Arrhenius Acids – produce H + ions (or hydronium ions H 3 O + ) Bases – produce OH - ions (problem: some bases don’t have hydroxide ions!)

7. Arrhenius acid is a substance that produces H + (H 3 O + ) in water Arrhenius base is a substance that produces OH - in water

8. Strong acid- ionizes completely in aqueous solution Strong electrolytes HCl, HNO3 Weak acid- releases few hydrogen ions in aqueous solution HCN and acetic acid (-COOH) Strong base- ionizes completely in aqueous solution Strong electrolytes Weak base- releases few hydroxide ions in aqueous solution

9. HNO 3, HCl, H 2 SO 4 and HClO 4 are among the only strong acids. Strong and Weak Acids/Bases Strong and Weak Acids/Bases The strength of an acid (or base) is determined by the amount of IONIZATION. STRONG=100% IONIZED

10. Weak acids are much less than 100% ionized in water. Weak acids are much less than 100% ionized in water. One of the best known is acetic acid = CH 3 COOH Strong and Weak Acids/Bases

11. Strong Base: 100% dissociated in water. Strong Base: 100% dissociated in water. NaOH (aq) ---> Na + (aq) + OH - (aq) NaOH (aq) ---> Na + (aq) + OH - (aq) Strong and Weak Acids/Bases Other common strong bases include KOH and Ca(OH) 2. CaO (lime) + H 2 O --> Ca(OH) 2 (slaked lime) Ca(OH) 2 (slaked lime) CaO

12. Weak base: less than 100% ionized in water Weak base: less than 100% ionized in water One of the best known weak bases is ammonia NH 3 (aq) + H 2 O (l)  NH 4 + (aq) + OH - (aq) Strong and Weak Acids/Bases

13. Definition #2: Brønsted – LowryBrønsted – Lowry Acids – molecule or ion that is a proton donor Bases – molecule or ion that is a proton acceptor A “proton” is really just a hydrogen atom that has lost it’s electron!

14. A Brønsted-Lowry acid is a proton donor A Brønsted-Lowry base is a proton acceptor acid conjugate base base conjugate acid

15. The Brønsted definition means NH 3 is a BASE in water — and water is itself an ACID

17. Lewis acid - a substance that accepts an electron pair Lewis base - a substance that donates an electron pair Definition #3 – LewisLewis Definition #3 – LewisLewis

18. Formation of hydronium ion is also an excellent example. Electron pair of the new O-H bond originates on the Lewis base.Electron pair of the new O-H bond originates on the Lewis base.

20. NO, NO 2, CO 2, SO 2, and SO 3 gases from industrial processes can dissolve in atmospheric water to produce acidic solutions. Burning of fossil fuels by coal-burning power plants, factories, and automobiles Very acidic rain is known as acid rain. Acid rain can erode statues and affect ecosystems. example:

22. Amphoteric Compounds Any species that can react as either an acid or a base is described as amphoteric. example: water water can act as a base acid 1 base 2 acid 2 base 1 water can act as an acid base 1 acid 2 acid 1 base 2

23. H 2 O can function as both an ACID and a BASE. In pure water there can be AUTOIONIZATION Equilibrium constant for water = K w K w = [H 3 O + ] [OH - ] = 1.00 x 10 -14 at 25 o C

24. In the self-ionization of water, two water molecules produce a hydronium ion and a hydroxide ion by transfer of a proton. -

26. K w = ionization constant of water K w = [H 3 O + ] [OH - ] = 1.00 x 10 -14 at 25 o C In a neutral solution [H 3 O + ] = [OH - ] so K w = [H 3 O + ] 2 = [OH - ] 2 and so [H 3 O + ] = [OH - ] = 1.00 x 10 -7 M Autoionization

27. Kw = [H +1 ][OH -1 ] = 1E-14 Used to find unknown [H +1 ] or [OH -1 ] if the other is known or given If [H +1 ] =.0003M, find the [OH -1 ] 1E-14 = [.0003M] [OH -1 ] [OH -1 ]=3.33E-11M

29. Base 10 logarithms (log) The log of a number is the power to which 10 must be raised to get that number log 1000 = 3 because 10 3 = 1000 log 0.1 = -1 because 10 -1 = 0.1 Use your calculator to solve log (1.25*10 -3 ) = -2.90 -log (3.64*10 -12 ) = 11.44

30. pH = - log [H + ] Example: If [H + ] =1E-10 pH = - log( 1E-10) pH = - (- 10) pH = 10 Example: If [H + ] = 1.8E-5 pH = - log 1.8E-5 pH = - (- 4.74) pH = 4.74

32. Find the pH of these: 1) A 0.15 M solution of Hydrochloric acid (answer:.8239) (answer:.8239) 2) A 3.00 X 10 -7 M solution of Nitric acid (answer: 6.5229) (answer: 6.5229) STOP STOP

33. If the pH of Coke is 3.12, [H + ] = ??? Because pH = - log [H + ] then - pH = log [H + ] - pH = log [H + ] Take antilog (10 x ) of both sides and get 10 -pH = [H + ] [H + ] = 10 -3.12 = 7.6 x 10 -4 M *** to find antilog on your calculator, look for “Shift” or “2 nd function” and then the log button *** to find antilog on your calculator, look for “Shift” or “2 nd function” and then the log button

34. A solution has a pH of 8.5. What is the Molarity of hydrogen ions in the solution? A solution has a pH of 8.5. What is the Molarity of hydrogen ions in the solution? pH = - log [H + ] 8.5 = - log [H + ] -8.5 = log [H + ] Antilog -8.5 = antilog (log [H + ]) 10 -8.5 = [H + ] 3.16E-9 M = [H + ] pH = - log [H + ] 8.5 = - log [H + ] -8.5 = log [H + ] Antilog -8.5 = antilog (log [H + ]) 10 -8.5 = [H + ] 3.16E-9 M = [H + ]

36. Since acids and bases are opposites, pH and pOH are opposites! Since acids and bases are opposites, pH and pOH are opposites! pOH does not really exist, but it is useful for changing bases to pH. pOH does not really exist, but it is useful for changing bases to pH. pOH looks at the perspective of a base pOH looks at the perspective of a base pOH = - log [OH - ] Since pH and pOH are on opposite ends, pH + pOH = 14

37. [OH - ] [H + ] pOH pH 10 -pOH 10 -pH -Log[H + ] Log[OH - ] -Log[OH - ] 14 - pOH 14 - pH 1.0 x 10 -14 [OH - ] [OH - ] 1.0 x 10 -14 [H + ] [H + ]

38. The pH of rainwater collected in a certain region of the northeastern United States on a particular day was 4.82. What is the H + ion concentration of the rainwater? (answer: 1.51E-5M) The OH - ion concentration of a blood sample is 2.5 x 10 -7 M. What is the pH of the blood? (answer: 7.3979)

39. Calculating [H 3 O + ], pH, [OH - ], and pOH Problem 1: Calculate the [H 3 O + ], pH, [OH - ], and pOH of a solution of 0.0024 M hydrochloric acid at 25°C. [H 3 O + ]= 0.0024 M pH= 2.62 [OH - ]= 4.17 E^-12M pOH= 11.38 End

40. Problem 2: What is the [H 3 O + ], [OH - ], and pOH of a solution with pH = 3.67? Is this an acid, base, or neutral? [H 3 O + ]= 10^ -3.67 = 2.14E-4 M [OH - ]= 10^-14 / (2.14E-4) = 4.67E-11 M pOH= 14 – 3.67 = 10.33 Acid

41. Tests the voltage of the electrolyte Tests the voltage of the electrolyte Voltage changes as hydronium ion concentration changes Voltage changes as hydronium ion concentration changes Converts the voltage to pH Converts the voltage to pH Very cheap, accurate Very cheap, accurate Must be calibrated with a buffer solution Must be calibrated with a buffer solution

42. Indicators are compounds that will change color in the presence of an acid or base. Indicators are either weak acids or weak bases Indicators only work in a specific range of pH Some dyes are natural, like radish skin or red cabbage

43. In aqueous solutions, neutralization is the reaction of hydronium ions and hydroxide ions to form water molecules. H 3 O + (aq) + OH  (aq)  2H 2 O(l) A salt is an ionic compound composed of a cation from a base and an anion from an acid.

44. Titration is the controlled addition and measurement of the amount of a solution of known concentration required to react completely with a measured amount of a solution of unknown concentration. The point at which the two solutions used in a titration are present in chemically equivalent amounts is the equivalence point. The point in a titration at which an indicator changes color is called the end point of the indicator.

45. Setup for titrating an acid with a base

48. 1. Add solution from the buret to the flask. 2. Reagent (base) reacts with compound (acid) in solution in the flask. 3. Indicator shows when exact stoichiometric reaction has occurred. (Acid = Base) This is called the END POINT where NEUTRALIZATION has occurred. This is called the END POINT where NEUTRALIZATION has occurred. Titration Math(short version) Titration Math(short version) M 1 V 1 = M 2 V 2 Moles H 3 O + = Moles OH -

49. Standard Solution = NaOH BURET Solution of Unknown Concentration = HCl

50. Set up the buret and the chemicals the same except no Phenolphthalein is added Set up the Nova with a pH sensor attached and insert the probe into the Unknown solution. Proceed with the addition of the base solution until the graph looks like the one attached The volume where the large jump takes place is the End Point, moles Base=moles Acid Begin calculations

51. Molarity and Titration 1.Start with the balanced equation for the neutralization reaction, and determine the chemically equivalent amounts of the acid and base. 2. Determine the moles of acid (or base) from the known solution used during the titration. 3.Determine the moles of solute of the unknown solution used during the titration using the balanced equation. 4. Determine the molarity of the unknown solution.

52. Problem: Determine the molarity of an acidic solution, 10 mL HCl, by titration. (HCl of unknown molarity in the flask, 5.0 x 10 -3 M NaOH in the buret) Titrate the acid with a standard base solution 20.00 mL of 5.0 × 10 −3 M NaOH was titrated 1. Write the balanced neutralization reaction equation. HCl(aq) + NaOH(aq) NaCl(aq) + H 2 O(l) 1 mol HCL reacts with 1 mol NaOH Determine the chemically equivalent amounts of HCl and NaOH.

53. 3. Calculate the number of moles of NaOH used in the titration. Then calculate the number of moles of HCl initially in the flask. 20.0 mL of 5.0 × 10 −3 M NaOH is needed to reach the end point Amount of HCl = mol NaOH = 1.0 × 10 −4 mol 4. Calculate the molarity of the HCl solution

54. Sample Problem F In a titration, 27.4 mL of 0.0154 M Ba(OH) 2 is added to a 20.0 mL sample of HCl solution of unknown concentration until the equivalence point is reached. What is the molarity of the acid solution?

55. Sample Problem F Solution Given: volume and concentration of known solution = 27.4 mL of 0.0154 M Ba(OH) 2 Unknown: molarity of acid solution Solution: 1. balanced neutralization equation  chemically equivalent amounts Ba(OH) 2 + 2HCl BaCl 2 + 2H 2 O 1 mol 2 mol

56. Sample Problem F Solution, continued 2. volume of known basic solution used (mL)  amount of base used (mol) 3. mole ratio, moles of base used moles of acid used from unknown solution

57. Sample Problem F Solution, continued 4. volume of unknown, moles of solute in unknown  molarity of unknown

58. Sample Problem F Solution, continued 1. 1 mol Ba(OH) 2 for every 2 mol HCl. 2. 3. 3.80 7.61 -4

59. Sample Problem F Solution, continued 4. End 3.8 7.61