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Acids, Bases and Salts Acid-Base Theories

Acids, Bases and Salts Acid-Base Theories. CHAPTER 15 PA 530-538. What is an Acid?. The term acid comes from the Latin term acere , which means " sour ". ex. Lemon juice, vinegar, and many other foods taste sour. Taste sour Corrosive React with some metals to produce H 2

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Acids, Bases and Salts Acid-Base Theories

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  1. Acids, Bases and SaltsAcid-Base Theories CHAPTER 15 PA 530-538

  2. What is an Acid? The term acid comes from the Latin term acere, which means "sour". ex. Lemon juice, vinegar, and many other foods taste sour.

  3. Taste sour Corrosive React with some metals to produce H2 Change Litmus to red acid= red React with bases to form water and salt. Bases taste bitter Feel slippery Corrosive Change Litmus to blue base = Blue Become less basic when mixed with acids. AcidsBases

  4. Always Use Ref. Tables (vinegar)

  5. Table L Common Bases • Formula Name • NaOH(aq) sodium hydroxide • KOH(aq) potassium hydroxide • Ca(OH)2(aq) calcium hydroxide • NH3(aq) aqueous ammonia

  6. Svante Arrhenius 1859 - 1927 Swedish chemist, proposed theories of electrolytic disassociation (acids/bases) and greenhouse effect.

  7. Arrhenius Theory of Acids & Bases Acid - produces hydrogen ion (H+) in a solution. HA  H+ + A¯ Base – produces hydroxide ion (OH¯) in a solution. XOH  X+ + OH¯

  8. Nature of the Hydrogen Ion or Proton • Proton is so small that does not exist isolated in water. • H+ + H2O  H3O + • Hydronium Ion

  9. Nature of Hydroxide Ion • The presence of OH- makes the substance an electrolyte and a base. • Alcohols contain the OH group but are NOT IONIC COMPOUNDS therefore alcohols are NOT bases. • C H O are molecular compounds NOT ionic compounds!!!!

  10. HOW TO NAME ACIDS • NO OXYGEN IN FORMULA • HYDRO ----- ACID HCl Hydrochloric acid HBr Hydrobromic acid HF Hydrofluoric acid H2S Hydrosulfuric acid • OXOA CIDS • CONTAIN OXIGEN IN FORMULA • ENDING • OUS if ion ends ITE • IC if ion ends in ATE • Use table E

  11. Solutions of Ionic Compounds conduct electricity = Electrolytes Electrolytes – ions (charged particles) in solution. HCl(aq) H+ + Cl- Hydrochloric Acid Cl - H+

  12. Electrolytes – conduct electricity when dissolved in H2O Solutions ; Release OH- (aq) Metal (+) and Non-Metal (-)

  13. = Salts (ionic), acids, & bases bright dim dark Solutions Salts = ionic (+) (-) Strong Acid & Base Weak Acid or Weak Base Covalent = no ions

  14. Conductivity apparatusElectrolytes – conduct electricity when dissolved in water

  15. STRONG ACIDS • COMPLETELY DISSOCIATED • If the solution is 2 M, 2 mol of H + and 2 mol of Cl-

  16. WEAK ACIDS • Partially dissociated. Molecules stay together and only some of them dissociate.

  17. Strong Acids Strong Bases • HI • HBr • HCl • HNO3 • H2SO4 • HClO4 • LiOH • NaOH • KOH • RbOH • CsOH

  18. Naming Acids

  19. Binary Acids- composed of hydrogen + 1 other elementEx. HCl Hydrochloric AcidBinary Acids begin with “hydro -”followed by name of other element; modified with an ending of “-ic”

  20. Ternary Acids - molecular (covalent)- composed of hydrogen + oxygen containing polyatomic ion (Ref. E)Ex.HNO3 Nitric Acid (NO31- Nitrate ion)HNO2 Nitrous Acid (NO21- Nitrite ion)H2SO4 Sulfuric Acid (SO42- Sulfate ion)Ternary Acids = Anion suffix (-ate or -ite) is dropped and replaced with “-ic” or “-ous” respectively.

  21. TABLE M common acids • HCl(aq) hydrochloric acid • HNO3(aq) nitric acid • H2SO4(aq) sulfuric acid • H3PO4(aq) phosphoric acid • H2CO3(aq) carbonic acid • CH3COOH(aq) ethanoic acid • HC2H3O2(aq) (acetic acid)

  22. Common Acids – Ref. K Nitric acid (HNO3) 1)  Most is used to make fertilizer 2)  Well known for making explosives Hydrochloric acid (HCl) 1)  Most is used to clean metals (pickling) 2)  Also called muriatic acid Sulfuric acid (H2SO4) 1)  The most widely used chemical in the world 2)  Most of it is used to make fertilizer 3)  It is a good dehydrating agent 4)  It is used in car batteries

  23. Properties of Bases Bases feel slippery Bases are electrolytes Bases are corrosive, poisonous, and can cause severe burns (Lye = conc. NaOH) Bases turn litmus blue; Blue = Base Bases = pH greater than 7 Big in Base 6)Bases neutralize acids

  24. Common Bases – Ref. L Ammonia NH3 1)  The most widely used base 2)  Used in household cleaning materials 3)  Used as fertilizer; adds nitrogen to soil Calcium hydroxide (caustic lime) Ca(OH)2 1)  Used  to make mortar and plaster 2)  Used to help neutralize acid soil Sodium hydroxide (Lye) NaOH 1)  One of the strongest bases 2)  Used in oven cleaners and drain cleaners

  25. Acids ending = “- ic” Bases = Metal + hydroxide Always Use Ref. Tables (vinegar)

  26. Reactions of Acid with metals • Use table J! • Metals above H2 in table J react with acids by a single replacement reaction producing H2. • 2 HCl + Zn  H2 + ZnCl2

  27. Neutralization Reaction Acids and bases react to neutralize each other, forming water and a salt: Acid + Base  Water + Salt HA + XOH  H2O + XA Double Replacement Reaction

  28. Titration • Is a process that uses a neutralization to determine the concentration of an acid or a base. Concentration in molarity is the amount of moles of solute per liter of solution. When the reaction of neutralization is 1:1 we use the following formula in a titration • Ma x Va = Mb x V b

  29. Vocabulary • Standard solution : the solution of known molarity • Buret : instrument to measure exact volumes of liquids • Erlenmeyer Flask • Indicator : a substance that changes color in the presence of an acid or base. • End point: when the amount of H+ = OH-

  30. At the end point • Ma x Va = Mb x V b

  31. Acid – Base Titration Two Burets with valves at bottom. Record vol. in mL (twice) Color indicator = phenolphthalein Acid H + Base OH - Erlenmeyer flask

  32. What is pH ? pH is the negative logarithm of the hydrogen ion concentration = pH = - log [H+] Remember that sometimes H+ is written H3O+, so pH = - log [H3O+] means the same thing.

  33. pH is.. Big in Base & Blue pH Scale = log (base 10) scale An increase of 1 in pH corresponds to a decrease of a factor of 10 in H+ concentration.

  34. Battery Acid Stomach Acid Lemon Juice Vinegar, Soft Drinks Acidic Tomatoes Typical pH Values of CommonMaterials Coffee / Tea Milk Saliva Neutral Pure Water Blood Seawater Baking Soda Soap Basic Ammonia (NH3) Hair Remover OvenCleaner / Drain Cleaner

  35. More about pH Kw = dissociation constant for water = 10-14 1 x 10-14 = [H+] x [OH-] = [ 10-7 ] x [ 10-7 ] A neutral solution has a pH of 7. [H+] = [OH-] = 1 x 10-7 M

  36. pH and [H+] If pH is… [H+] = ?? pH = 8 _____ pH = 12 _____ pH = 6 _____ pH = 2 _____

  37. Finding pH for a solution of a strong acid or strong base • For strong acid the concentration of the acid is the same as H+ • For strong bases the concentration of the base is the same as OH-.

  38. Find the pH for • A) 0.0001 M HCl • B) 0.01 M HBr • C) 0.001 M NaOH

  39. Acid-Base Indicators • A substance that have different colors at different pH.

  40. Always Use Ref. Tables (vinegar)

  41. Bronsted Lowry definition • An ACID is a substance that donates H+ • A BASE is a substance that ACCEPTS H+

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