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The Acid Test

The Acid Test. Acids, Bases and pH . Range of pH scale . The pH scale ranges from 0 to 14. There are no units of measure for pH * . What do the numbers mean? . A pH of 7 is neutral Pure water has a pH of 7*. How about below 7? . Anything below 7 is acidic

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The Acid Test

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  1. The Acid Test Acids, Bases and pH

  2. Range of pH scale • The pH scale ranges from 0 to 14. • There are no units of measure for pH *

  3. What do the numbers mean? • A pH of 7 is neutral • Pure water has a pH of 7*

  4. How about below 7? • Anything below 7 is acidic • 0 is the most acidic and 6.99999 is the least acidic • The further something is from 7 the more acidic it is*

  5. How about above 7? • higher than 7 is basic/alkaline • So 7.000001 is a weak base and 14 is the most basic (or alkaline)*

  6. pH Range 0 1 2 3 4 5 6 7 8 910 11 12 13 14 Neutral [H+]>[OH-][H+] = [OH-][OH-]>[H+] Acidic Basic

  7. The pH Scale • pH measures acidity and alkalinity (how basic) a liquid is*

  8. Ionization of Water Occasionally, in water, a H+ is transferred between H2O molecules . . . . . . . . H:O: + :O:H H:O:H + + :O:H- . . . . . . . . HH H water molecules hydronium hydroxide ion (+)ion (-)

  9. Measuring pH Litmus paper, pH paper, and pH meters*

  10. Litmus paper • Litmus paper cannot tell you the exact pH of a substance. • It can only tell you if it is an acid or a base • Blue litmus turns pink in the presence of an acid • Red litmus turns blue in the presence of a base*

  11. pH paper • pH paper can tell you approximate pH values. • By placing one end of the pH paper in the solution it will turn a color which can be matched to the color code key. *

  12. Indicators • Indicators: • Weak organic acids and bases whose colors differ from the colors of their conjugate acids or bases. • The color is best viewed from above against a white background

  13. Acid / Base Indicators • Indicator • Lower Color • pH Range • Upper Color • methyl violet • yellow-green • 0.0 - 2.5 • violet • methyl orange • red • 2.5 - 4.4 • yellow • congo red • blue • 3.0 - 5.0 • red • bromocresol green • yellow • 4.5 - 5.5 • blue • methyl red • red • 4.8 - 6.0 • yellow • bromocresol purple • yellow-green • 5.4 - 6.8 • violet • bromothymol blue • yellow • 6.0 - 7.6 • blue • phenol red • yellow • 6.4 - 8.2 • red-violet • cresol red • yellow • 7.1 - 8.8 • violet • phenolphthalein • colorless • 8.3 - 10.0 • dark pink • Phenolphthalein is a common indicator to use in neutralization titrations. The solution is considered neutral when the solution holds a very faint pink color for half a minute or more. • alizarin yellow R • yellow • 9.9 - 11.8 • dark orange Table of Indicators

  14. pH Meter • The most precise and usually more accurate way to measure pH is using a pH meter which directly measures the amount of [H3O+] in the solution • Uses an electrode which specifically measures the pH of the solution. • This is a larger model. Some are small enough to be hand-held.*

  15. What is an Acid? • Sour Taste (We never taste chemicals in lab) • release hydrogen (H+) • React with metals to release H2 • React with a base to produce water and a salt (neutralization reaction) • Some that completely dissociate conduct current (electrolytes) • Turns blue litmus paper red*

  16. Naming Acids Binary (begin with hydro-) Oxyacids do not have hydro- *

  17. Naming Binary Acids • Binary acids contain hydrogen and one other element • Binary acids begin with hydro- • Binary acids end with –ic*

  18. HF HCl HBr HI H2S Hydrofluoric acid Hydrochloric acid Hydrobromic acid Hydroiodic acid Hydrosulfuric acid* Test your naming skills of these acids

  19. Oxyacid • An acid that is a compound of hydrogen, oxygen and a third element (usually a nonmetal) • These do not contain hydro- • Can end in either –ic or –ous*

  20. CH3COOH H2CO3 HIO3 HClO HClO2 HClO3 HClO4 HNO2 Acetic acid Carbonic acid Iodic acid Hypochlorous acid Chlorous acid Chloric acid Perchloric acid Nitrous acid* Name these Oxyacids

  21. HNO3 H3PO4 H3PO3 H2SO4 H2SO3 Nitric acid Phosphoric acid Phosphorous acid Sulfuric acid Sulfurous acid* Name these oxyacids

  22. Common Industrial Acids • Sulfuric • Nitric • Phosphoric • Hydrochloric • Acetic *

  23. Sulfuric • Most commonly produced acid worldwide • Petroleum refining • Metallurgy • Fertilizer manufacturing • Production of metal, paper, paint, dyes, detergents • Automobile batteries*

  24. Sulfuric Acid • Can be used to dehydrate (water removing) • Sugar can be dehydrated by this acid • Has the same effect on organic tissue causing severe burns *

  25. Nitric Acid • Volatile and unstable in its pure form • Rarely used in its pure form • Stains yellow and burns skin • Used in the making of explosives rubber, plastics, dyes and pharmaceuticals *

  26. Phosphoric Acid • Manufacture of fertilizer and animal feed • Flavoring agent in dilute form • Cleaning agent for dairy equipment • Manufacture of detergents and ceramics*

  27. Hydrochloric acid • Produced in your stomach to aid in digestion • Used to remove surface impurities of metals (iron and steel) • Cleaning agent in food industry • Also known as muriatic acid in a dilute form • Adjust the pH of Swimming pools*

  28. Different Definitions of Acids and Bases Arrhenius Bronsted-Lowry Lewis*

  29. Arrhenius Acids and Bases • Arrhenius acid is a chemical compound that increased the concentration of H+ in an aqueous solution • Arrhenius base is a chemical that increases the concentration of OH- ions in an aqueous solution *

  30. Acids Taste sour Donate a H+ pH less than 7 Turn litmus paper red Turn bromothymol blue to yellow Turn phenolphthalein colorless Neutralize bases Bases Taste bitter Usually ends in -OH pH greater than 7 Turn litmus paper blue Turn bromothymol blue to blue Turn phenolphthalein pink Feel slippery to touch Neutralize acids* Characteristics of Acids and Bases

  31. Learning Check AB1 Describe the solution in each of the following as: 1) acid 2) base or 3)neutral. A. ___soda B. ___soap C. ___coffee D. ___ wine E. ___ water F. ___ grapefruit*

  32. Solution AB1 Describe each solution as: 1) acid 2) base or 3) neutral. A. _1_ soda B. _2_ soap C. _1_ coffee D. _1_ wine E. _3_ water F. _1_ grapefruit*

  33. Learning Check AB2 Identify each as characteristic of an A) acid or B) base ____ 1. Sour taste ____ 2. Produces OH- in aqueous solutions ____ 3. Chalky taste ____ 4. Is an electrolyte ____ 5. Produces H+ in aqueous solutions*

  34. Solution AB2 Identify each as a characteristic of an A) acid or B) base _A_ 1. Sour taste _B_ 2. Produces OH- in aqueous solutions _B_ 3. Chalky taste A, B4. Is an electrolyte _A_ 5. Produces H+ in aqueous solutions*

  35. Arrhenius Acids and Bases • Acids produce H+ in aqueous solutions water HCl H+(aq) + Cl- (aq) • Bases produce OH- in aqueous solutions water NaOH Na+(aq) + OH- (aq)*

  36. Learning Check AB3 Give the names of the following A. HBr (aq) 1. bromic acid 2. bromous acid 3. hydrobromic acid B. H2CO3 1. carbonic acid 2. hydrocarbonic acid 3. carbonous acid*

  37. Solution AB3 A. HBr 3. hydrobromic acid The name of a nonoxy acid begins with the prefix hydro- and ends with -ic acid. In a nonoxy acid, the negative anion end in -ide. B.H2CO3 1. carbonic acid The name of an oxyacid is named with the stem of the anion (carbonate) changed to -ic acid *

  38. Some Common Bases NaOH sodium hydroxide KOH potassium hydroxide Ba(OH)2 ________________________ Mg(OH)2________________________ Al(OH)3 aluminum hydroxide*

  39. Learning Check AB4 Match the formulas with the names: A. ___ HNO2 1) hydrochloric acid B. ___ Ca(OH)2 2) sulfuric acid C. ___ H2SO4 3) sodium hydroxide D. ___ HCl 4) nitrous acid E. ___ NaOH 5) calcium hydroxide*

  40. Solution AB4 Match the formulas with the names: A. _4__ HNO21) hydrochloric acid B. _5__ Ca(OH)2 2) sulfuric acid C. _2__ H2SO4 3) sodium hydroxide D. _1__ HCl 4) nitrous acid E. _3__ NaOH 5) calcium hydroxide*

  41. Learning Check AB5 Acid, Base Name or Salt CaCl2 ______ _________________ KOH ______ _________________ Ba(OH)2 ______ _________________ HBr ______ _________________ H2SO4* ______ __________________

  42. Solution AB5 Acid, Base Name or Salt CaCl2 salt calcium chloride KOH base potassiuim hydroxide Ba(OH)2 base barium hydroxide HBr acid hydrobromic acid H2SO4 acid sulfuric acid*

  43. Bronsted-Lowry Acids Acids are hydrogen ion (H+) donors Bases are hydrogen ion (H+) acceptors HCl + H2O H3O+ + Cl- donor acceptor + - + +

  44. Strengths of Acids and Bases Strong acids completely ionize (100%) in aqueous solutions HCl + H2O H3O+ + Cl- (100 % ions) Strong bases completely (100%) dissociate into ions in aqueous solutions. NaOH Na+ (aq) + OH-(aq) (100 % ions)*

  45. NH3, A Bronsted-Lowry Base When NH3 reacts with water, most of the reactants remain dissolved as molecules, but a few NH3 reacts with water to form NH4+ and hydroxide ion. NH3 + H2O NH4+(aq) + OH- (aq) acceptor donor + +

  46. Strong and Weak Acids and Bases Strong acids HCl, HNO3 ,H2SO4 Most other acids are weak. Strong bases NaOH, KOH, and Ca(OH)2 Most other bases are weak.*

  47. Learning Check SW1 Identify each of the following as a 1) strong acid or base 2) weak acid 3) weak base A. ___ HCl (aq) B. ___ NH3(aq) C. ___ NaOH (aq) D. ___ H2CO3 (aq)

  48. Solution SW1 Identify each of the following as a 1) strong acid or base 2) weak acid 3) weak base A. _1__ HCl (aq) B. _3__ NH3(aq) C. _1__ NaOH (aq) D. _2__ H2CO3 (aq)*

  49. Antacids • Used to neutralize stomach acid (HCl) • Many contain one or more weak bases Alka-Seltzer: NaHCO3, citric acid, and aspirin Di-gel: CaCO3 and Mg(OH)2 Gelusil: Al(OH)3and Mg(OH)2 Maalox: Al(OH)3and Mg(OH)2 Mylanta: Al(OH)3 and Mg(OH)2*

  50. More Antacids Milk of Magnesia: Mg(OH)2 Rolaids: AlNa(OH)2CO3 aluminum sodium dihydroxy carbonate Tums: CaCO3 Tempo: CaCO3,Al(OH)3,Mg(OH)2*

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