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Acid and Base Chemistry

Acid and Base Chemistry. Review. Acids pH less than 7 Turns litmus from blue to red Sour taste Bases pH greater than 7 Turns litmus from red to blue “slippery” feeling. Definitions. Arrhenius Acids produce H+ ions, bases produce OH- ions in aqueous solutions

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Acid and Base Chemistry

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  1. Acid and Base Chemistry

  2. Review • Acids • pH less than 7 • Turns litmus from blue to red • Sour taste • Bases • pH greater than 7 • Turns litmus from red to blue • “slippery” feeling

  3. Definitions • Arrhenius • Acids produce H+ ions, bases produce OH- ions in aqueous solutions • Limits the number of reactions considered Acid-Base • Bronsted-Lowry • Acid is an H+ donor • Base is an H+ acceptor • Lewis • Acid Accepts an electron pair • Base donates an electron pair

  4. Properties of acids • Sour taste citric, malic, tartaric are well known food additives

  5. Properties of Acids 2. Contain the hydrogen ion (H+ ), react with active metals to give off H2 gas

  6. Properties of Acids • Change the color of indicators Low pH

  7. Properties of acids 4. React with bases to produce salts and water Base + Acid → Water + Salt 2NaOH + H2SO4→ 2H2O + Na2SO4

  8. Properties of Acids • Acids are electrolytes Break apart and form ions can conduct electricity

  9. Common acids HCl – hydrochloric acid H2SO4 – sulfuric acid HC2H3O2 – acetic acid - vinegar HNO3 – nitric acid H3PO4 – phosphoric acid H2CO3 – carbonic acid

  10. Hydrochloric Acid (Muriatic Acid) Produced in the stomach and aids in digestion Industrial Cleaning Agent

  11. Sulfuric Acid • #1 industrial chemical • Fertilizers, petroleum refining, metallurgy • Production of metal, paper, paint, detergents • Used as a measure of a country’s economy

  12. Acetic Acid • Dilute acetic acid is vinegar • Used in making plastics • Raw material necessary in the production of food supplements

  13. Nitric Acid Explosive making uses nitric acid, due to its instability Used in the rubber and plastics industry Dyes and drug production also utilize nitric acid

  14. Phosphoric Acid Manufacture of fertilizers and animal feed Detergents and ceramics also utilize phosphoric acid Carbonated beverage production

  15. Carbonic Acid Made from dissolving carbon dioxide (CO2) in water Sodas, or any carbonated beverage.

  16. Monoprotic Acid vsDiproticacid • Monoprotic Acids donate 1 proton (H+) • IeHCl • Diprotic Acids donate (2) protons (H+) per molecule • Ie: H2SO4

  17. Triprotic acids • Donates (3) protons • Example: H3PO4

  18. Strong vs Weak Acids and Bases • Does not mean dangerous vs safe • Strong Acids ionize completely • Every available H+ ion is separated from anion in aqueous solution • If 0.1 mol of HCl is added to water, then 0.1 mol of H+, and 0.1 mol of Cl- are fromed • Table 4.1 • Weak Acids do not ionize completely • We use a reversible reaction (double) arrow to represent not complete ionization

  19. Bases

  20. Properties of bases 1. Bitter taste

  21. Properties of Bases 2. Feel slippery to the skin • Change color of indicators High pH

  22. Properties of Bases • React with acids to produce water and salts 2NaOH + H2SO4 → 2H2O + Na2SO4 5. Bases are electrolytes

  23. Common bases

  24. Sodium hydroxide (NaOH), also known as lye or caustic soda, is a caustic metallic base. It is widely used in many industries, mostly as a strong chemicalbase in the manufacture of pulp and paper, textiles, drinking water, soaps and detergents. Worldwide production in 1998 was around 45 million tons.

  25. Ammonium hydroxide (NH4)(OH) Common household cleaner

  26. pH scale

  27. pH Equation • - log [H+] • If [H+] = 1 x 10-8M • Then –log[1 x 10-8] = pH pH = 8

  28. pH Equation Notice pH can be estimated by the exponent -log(1.0 x 10-5) = pH of 5 -log(1.0 x 10-9) = pH of 9 -log(1.0 x 10-13) = pH of 13

  29. If [H+] = 3.4 x 10-5 find pH = -[(log 3.4 x 10-5)] = -[(log 3.4 + log 10-5)] = -[(0.53) + (-5)] = -(0.53 – 5) = 4.47

  30. Reactions • Neutralization of Acids / Base • When acid and base react to an equivalence point • Where all H+ ions have reacted with all OH- ions to produce _________? “Spectator Ions” – Ions that do not actually take part in the reaction. Often times, the other ion in the acid or base, that gets separated from the H+ or OH- doesn’t really take part in the reaction.

  31. If [H+] = 3.4 x 10-5 find pH = -[(log 3.4 x 10-5)] = -[(log 3.4 + log 10-5)] = -[(0.53) + (-5)] = -(0.53 – 5) = 4.47

  32. Neutralization reactions • React an Acid and a Base together to form water, bring pH to neutral • Reaction of hydronium ions (H3O+) and hydroxide (OH-) ions to form water • Hydronium is sometimes simplified to H+ H3O++OH- 2H2O or H+ +OH- H2O or H+OH-

  33. Titration • Controlled addition & measurement of an amount of solution of a known concentration, that is required to react completely with a measured amount of solution of unknown concentration. • Example: HCl + NaOH NaCl + H2O A 100.0 mL sample of HCl is titrated to a stoichiometric endpoint with 76.8 mL of a 1.17 M NaOH. What is the molarity of the HCl?

  34. Acid-Base Titrations • Reaction to an equivalence point (pH 7) • Used to determine the concentration of an unknown solution. • If you find how much volume of a known concentration (standard) you need to add to a known volume of an unknown concentration…… • If I have 25.0 mL of a .316 M solution of H2SO4, What volume of NaOH do I need to neutralize it?

  35. Graph of titration typical titration curve

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