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Acids and Bases

Acids and Bases. Acid. Base. Taste-----sour Touch stings Reacts vigourously with metals Conducts Blue litmus turns red . Taste-- bitter Touch- slippery Little reaction with metals Conducts Red litmus turns blue.

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Acids and Bases

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  1. Acids and Bases

  2. Acid Base • Taste-----sour • Touch stings • Reacts vigourously with metals • Conducts • Blue litmus turns red Taste-- bitter Touch- slippery Little reaction with metals Conducts Red litmus turns blue

  3. There are 3 definitions of acids and bases. Each definition allows more substances to be classified as an acid or base

  4. Arrhenius Definition • Arrhenius Acid- substance that ionizes to produce H+ ions ex- HCl • Arrhenius Base- substance that dissociates to produce OH- ions ex- NaOH • Problem- must be in a water solution

  5. Bronsted-Lowery Definition • Acid- any substance that donates H+ • Base- any substance that accepts H+ • This definition allowed Ammonia (NH3) to be classified as a base • Water solution is NOT necessary

  6. Lewis Definition • Uses electrons and usually deals with organic chemistry

  7. Common Acids and uses • HCl- hydrochloric acid- stomach acid and concrete cleaner • H2SO4- sulfuric acid- dehydrating agent, fertilizers • HNO3- Nitric acid- explosives H3PO4- Phosphoric Acid- soft drinks CH3COOH- Acetic Acid- vinegar

  8. Common Bases • NH3 Ammonia- cleaner • NaOH- sodium hydroxide-lye soap, drain cleaner • Mg(OH)2- Magnesium hydroxide- antacid- MOM • Ca(OH)2- Calcium hydroxide- antacid

  9. Bases usually contain OH- (hydroxide) but carbonates and phosphates can form basic salts • NaOH, Ca(OH)2 • Salts: CaCO3 Na3PO4 • Calcium carbonate is found in chalk, TUMS, sea shells

  10. Organic bases contain the amine functional group • (-NH2)

  11. The term alkaline refers to a base solution • Example- shampoo commercial advertises that the shampoo is a slightly alkaline (slightly basic)

  12. Acids ionize to form a H+ ion

  13. Monoprotic- 1 ionizable H+ • Examples: HCl, HF, HBr,

  14. Diprotic Acid- contains 2 hydrogen • H2SO4

  15. Triprotic Acid- contains 3 hydrogens • H3PO4 Phosphoric

  16. A Binary Acid is an acid that contains hydrogen and one other element • HBr • HCl • HF

  17. Oxyacid- an acid that contains oxygen • H2SO4 • HNO3 H3PO4

  18. Carboxylic Acid- An organic acid that will always contain the functional group -COOH • Example- Acetic Acid CH3COOH

  19. Strong Acid ionizes completely to produce strong electrolytes • HCl H+ + Cl- • HI and HBr are also strong acids (will discuss diprotic acids later)

  20. Weak Acids ionize incompletely to form weak electrolytes • HF H+ + F- • What property explains why Flourine and hydrogen refuses to break apart completely?

  21. Strong bases- break apart completely • NaOH Na+ + OH- Remember: Groups 1 and 2 except for Be and Mg

  22. Weak bases break apart incompletely • Al(OH)3 Al+3 + OH-

  23. Acid Naming rules • See handout from class- make sure that you can name if given the root acid. • (this will be the last thing we do for this test- it may have to be postponed until the next test)

  24. Neutralization reaction • Acid + Base = salt + water • Sodium hydroxide + Hydrochloric Acid Salt: cation comes from the base and the anion from the acid.

  25. Sulfuric Acid + Sodium hydroxide • Carbonic Acid + Aluminum hydroxide

  26. Salts can react in neutralization rx • Hydrochloric Acid + Magnesium carbonate • Phosphoric acid + Calcium carbonate

  27. Buffers • Buffers are acids or bases that are used to prevent the pH from changing. • Bronsted-Lowery definitions for acids and bases explain buffers

  28. How buffers work • Buffers works by absorbing excess H+ or OH- in a solution. This prevents the pH from changing.

  29. Examples: • Antacids work by absorbing excess stomach acid- • They contain a buffer that prevents the stomach’s pH from changing too drastically to a basic pH

  30. Baking soda(homemade antacid) is not buffered. The pH is changed to much and the stomach releases more stomach acid and the indigestion process continues.

  31. Other common uses of buffers • Fish tanks, blood system, swimming pools

  32. Blood system—real life example • Hyperventilation- person breathes too rapidly • Too much CO2 is lost • pH of the blood increases (too basic)

  33. treatment Breathe into a bag air is rich with CO2 causes an increase in the H+ and the pH decreases back to normal

  34. Heart Failure • Person fails to release CO2 • Too much CO2 in blood system • pH of blood becomes too acidic (low pH)

  35. Treatment • IV of sodium bicarbonate(basic salt) • Increases the pH back to normal

  36. Amphoteric • A substance the can react as an acid or base depending on the chemical it is reacting with. • Examples- Al(OH)3 Water

  37. pH • Water is capable of self ionizing

  38. 1.o Liter of water produces 1.0 x 10-7 moles of H3O+ and 1.0 x 10-7 moles of OH- • This allows the Ionization constant for water to be calculated

  39. Calculate the H3O+ and the OH- • 1) .00236 M HCl 2) .0000569 M NaOH • 3) 2.69 x 10-3 M HBr 4) 4.14 x 10-11 M KOH

  40. pH is a way of expressing the hydronium ion concentration • pH scale 7 is neutral • less than 7= acid greater than 7= base

  41. Calculate the pH for the following: • .000569 M HCl 2) .00489 M HBr 3) 5.69 x 10-5 M HCl

  42. pOH is a way of expressing the hydroxide ion

  43. Calculate the pOH • 5.69 x 10-6 M NaOH • .00896 M KOH

  44. Determine the 1) hydronium 2) hydroxide • 3) pH 4) pOH • .00553 M HI • 7.23 x 10-4 M LiOH

  45. When given the pH or the pOH the H3O+ and OH- can be calculated: • H3O+ = antilog(-pH) or 10-pH • OH- = antilog (-pOH) or 10-pOH Remember the pH or pOH must be typed in as a negative number

  46. Calculate the hydronium and hydroxide ion concentration for each of the following: • 1) pH = 6.43 • 2) pOH = 3.43 • Identify if the substances are acidic ore basic

  47. Calculate the hydronium and hydroxide ion concentration for each of the following: • 1) pH = 2.56 • 2)pOH = 3.22 • Identify if the substances are acidic ore basic

  48. Sample lab problem • How many grams of HCl in a 500 mL solution would be needed to make a solution that has a pH of 2.55? • Hint- first calculate the molarity of the hydronium ion. • second- calculate the number of grams required to make this Molarity solution. (don’t worry- we are smushing the material)

  49. Answer:

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