1. Acids and Bases

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4. Acids and Bases Acids and Bases are one way of classifying matter through its properties.

5. Properties of Acids and Bases

6. Acids Sour taste

7. Acids Reacts with carbonates to form CO 2 gas MgCO 3(s) + 2HCl (aq) → MgCl 2(aq) + H 2 O (l) + CO 2(g) carbonate acid salt water carbon dioxide *Remember that you can test for CO 2 using a burning splint. The CO 2 gas will put out the flame of the burning splint.

8. Acids React with metals to form a salt compound and hydrogen gas (pop!) 2 HCl + Mg  MgCl 2 + H 2 acid metal salt hydrogen gas *Remember that you can test for H 2 using a burning splint. The H 2 gas will make a popping sound and put out the flame of the burning splint.

9. Acids Electrolytes - chemicals that dissociate when in water

10. Acids

11. Turn litmus paper red

12. Acids No color change with phenolphthalein indicator

13. Acids ph < 7

14. Acids

15. Bases Bitter taste

16. Bases Feel slippery

17. Bases Electrolytes

18. Bases Turn litmus paper blue

19. Bases Turns pink with phenolphthalein indicator

20. Bases ph > 7

21. Neutral solutions Substances that have neither acidic nor basic properties do not change the color of red or blue litmus paper or phenolphthalein pH equals 7 nonelectrolytes chemwiki

22. Definitions of Acids and Bases

23. Arrhenius Definition Arrhenius acids - give (donate) hydrogen ions (H + ) in aqueous solution. *an H + ion is a proton

24. Arrhenius Acid

26. Arrhenius bases – give (donate) hydroxide ions (OH) -1 in aqueous solution.

27. Arrhenius Base

28. Practice Using the Arrhenius definition, classify the following as an acid or a base in water 1.HI 2.HNO 3 3.Ca(OH) 2 4.H 2 SO 4 5.Mg(OH) 2 Acid, in water HI  H + + I - Acid, in water HNO 3  H + + NO 3 - Base, in water Ca(OH) 2  Ca +2 + 2OH - Base, in water Mg(OH) 2  Mg +2 + 2OH - Acid, in water H 2 SO 4  2H + + SO 4 -2

29. Brönsted-Lowry Definition Acids donate a proton or H + Bases accept a proton or H +

30. Brönsted-Lowry Definition

32. A conjugate base is the remainder of the original acid, after it donates its hydrogen ion A conjugate acid is the particle formed when the original base gains a hydrogen ion

33. Practice: Brönsted-Lowry Acids and Bases Identify the B-L acid (a), conjugate base (c.b.), B-L base (b), and conjugate acid (c.a.) 1. HCl + H 2 O ↔ H 3 O + + Cl - 2. HNO 2 + H 2 O ↔ H 3 O + + NO 2 - 3. SO 3 -2 + H 2 O ↔ HSO 3 - + OH - Ans: acid + base ↔ c.a. + c.b Ans: base + acid ↔ c.a. + c.b

34. The pH concept Acidic Alkaline (basic) Neutral www.fcs.ext.vt.edu

35. pH scale 35 [H + ] [OH - ] 1407

36. pHpH (8:53) formula: pH = -log[H + ] where [H + ] = concentration of H + ions

37. Example 1: What is the pH of a solution with [H + ] = 1 x 10 -3 M? formula: pH = -log[H + ] where [H + ] = concentration of H + ions Example 2: What is the pH of a solution with [H + ] = 1 x 10 -8 M?

38. The pH concept 1. [H + ] = 0.01 M 2. H + ] = 0.0001 M 3. [H + ] = 10 -7 M 4. [H + ] = 0.015 M 5. [H + ] = 3.2 x 10 -10 M 6. [H + ] = 6.5 x 10 -4 M 7. [H + ] = 4.5 x 10 -8 M pH = 2, acid Practice: Find the pH of the following solutions and state whether the solution is an acid, base or neutral. pH = 4, acid pH = 1.8, acid pH = 9.5, base pH = 3.2, acid pH = 7, neutral pH = 7.3, base

39. Strong Acids and Bases Strong acids completely dissociate and release [H + ] ions. HCl  H + + Cl - Strong bases completely dissociate and release [OH - ] ions. NaOH  Na + + OH - These are the ONLY strong acids: HCl, HBr, HI, HNO 3, HClO 4, H 2 SO 4 Some strong bases – NaOH, KOH, LiOH

40. Strong acids Weak Acids s-owl.cengage.com

41. Particle diagrams 41 strong acid – complete dissociation weak acid – partial dissociation

42. H + concentration of Strong and Weak Acids en.wikibooks.org How is the pH related to the H + ion concentration of weak and strong acids?

43. Acid Base Concentration Molarity- The number of moles of solute dissolved in 1.00 L of solution Molarity (M) = Moles of solute Liter of solution Example: What is the molarity of the solution if 2.0 moles of hydrochloric acid are added to 5.0 L of solution? M = 2.0 mol = 0.40 M 5.0 L 43

44. Concentrated vs. Dilute Concentrated acids and bases have a relatively large # of moles (of acid or base) per liter of solution. Dilute acids and bases have a relatively small # of moles (of acid or base) per liter of solution. 10.0 M HF is more concentrated than 2.0 M HF. 2.0 M KOH is more dilute than 10.0 M KOH. 44

46. Two acids, HCl and HC 2 H 3 O 2 are both 0.10 M. Which has a higher pH and why? H + Concentration of Strong and Weak Acids

47. Diluting Solutions Diluting Solutions: V 1 M 1 = V 2 M 2 Example: What volume of 2.0 M H 2 SO 4 would you need to prepare 100. mL of 0.40 M H 2 SO 4 ? 47

48. Indicators Chemicals that change color in the presence of an acid or a base Used to determine the pH of a solution Examples: litmus paper (red and blue), pH paper, phenolphthalein, red cabbage juice www.erowid.org catalog.flatworldknowledge.com

49. Indicators

50. Acid Vocabulary Binary acid – acid that contains only H and one other type of atom Ex. HBr, H 2 S Ternary acid – acid that contains H and a polyatomic ion Ex. H 2 SO 4 Monoprotic acid – acid that only has one H atom Ex. HBr, HI Polyprotic acid – acid that has more than one H atom Ex. H 2 S, H 3 PO 4 *a hydrogen ion, H +, is a proton

51. Naming Acids binary

52. Naming AcidsNaming Acids (stop at 5:47) No Oxygen  w/Oxygen Examples:HCl – hydrochloric acid HClO 3 – chloric acid HClO 2 – chlorous acid binary ternary

53. Practice Name the following acids: 1.HI 2.HF 3.H 2 SO 4 4.H 2 SO 3 5.H 2 CO 3 Write the chemical formula: 1.Hydrobromic acid 2.Hydrosulfuric acid 3.Acetic acid 4.Phosphoric acid 5. Nitrous acid Hydroiodic acid Hydrofluoric acid sulfuric acid sulfurous acid carbonic acid H2SH2S HC 2 H 3 O 2 H 3 PO 4 HNO 2 HBr Symbol, ox #, criss-cross

54. Hydroxides (OH - ) NaOH sodium hydroxide Mg(OH) 2 magnesium hydroxide Al(OH) 3 aluminum hydroxide Naming Bases Ammonia - NH 3 is a common base found in household glass cleaners. Most bases are named the same as any other ionic compound, for example:

55. Writing formulas for acids and bases Symbol, charge, criss-cross to get the subscripts. Example: hydrochloric acid Example: potassium hydroxide

56. Practice writing formulas for bases 1.Zinc hydroxide 2. Iron (II) hydroxide 3. Calcium hydroxide 4. Lithium hydroxide

57. Neutralization one type of double replacement reaction Reactants are acid and base, products are salt and water Acid + Base  Salt + water HCl + NaOH  NaCl + H 2 O 57

58. TitrationTitration (6:52) A controlled acid-base neutralization reaction The process of finding the concentration of an unknown solution by using a certain volume of a known concentration solution.

59. 59 This solution is also called the analyte or titer Unknown concentration known concentration

60. End point of a titration The point where neutralization is achieved Occurs just before the indicator has changed color DETERMINED BY OBSERVATION, DURING THE TITRATION EXPERIMENT 60

61. Equivalence Point the stoichiometric end point of a titration when moles of H + from acid = moles of OH - from base DETERMINED FROM THE DATA COLLECTED IN THE TITRATION EXPERIMENT

62. 62

63. Neutralization Problems- (#H + )M A V A = M B V B (#OH - ) #H + = #H in chemical formula M A = molarity of acid V A = volume of acid M B = molarity of base V B = volume of base #OH - = #OH in chemical formula 63

64. Practice: Neutralization Problem (#H + )M A V A = M B V B (#OH - ) When 45.0 mL of 3.00 M HBr is added to 80.0 mL of Ca(OH) 2 What is the molarity of the Ca(OH) 2 that was neutralized? #H + = M A = V A = M B = V B = #OH - = 64

65. Practice: Neutralization Problem (#H + )M A V A = M B V B (#OH - ) In a titration experiment, if 65.0 mL of an HCl solution reacts with 47.2 mL of a 0.65-M NaOH solution, what is the concentration of the HCl solution? #H + = M A = V A = M B = V B = #OH - = 65

66. Ion Stoichiometry : ) H 2 SO 4 + 2NaOH  Na 2 SO 4 + 2H 2 O 240 grams of NaOH react with sulfuric acid. How many moles of H + ions are consumed?