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Drill #8 5/1 & 2/14

Drill #8 5/1 & 2/14. What do you do if you spill acid in the lab? Do you add acid to water or water to acid?. Drill #8 5/1 & 2/14. How do you clean up an acid spill? Tell your instructor immediately

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Drill #8 5/1 & 2/14

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  1. Drill #8 5/1 & 2/14 What do you do if you spill acid in the lab? Do you add acid to water or water to acid?

  2. Drill #8 5/1 & 2/14 How do you clean up an acid spill? • Tell your instructor immediately • Place baking soda (base) over it to neutralize and clean up with paper towels. Do you add acid to water or water to acid? • Acid to water

  3. Objectives SWBAT: • Define acid rain and it’s effects on our environment • list major differences between acids and bases • list products of neutralization reactions • distinguish between 2 methods of defining acids and bases. • list properties of a salt

  4. Agenda • Solutions/Mixture Quiz (15 mins) • Acid Rain Reading (20 mins) • Notes on Acids and Bases (50 mins) • Worksheets

  5. Homework Due • Naming Acids WS

  6. Acid Rain Reading • Look at the following pictures on the powerpoint. From the pictures and your own experiences, what are some of the damaging effects of acid rain?

  7. Reading Activity: Acid Rain Before, During and After Reading (20 minutes)

  8. Acids and Bases

  9. Properties of Acids (in aq solution) • Sour taste • Low pH • Turn blue litmus paper red • Conduct electrical current

  10. Properties of Bases (in aq solution) • Bitter taste • Slippery • High pH • Turn red litmus paper blue • Conduct electrical current

  11. What happens when Mg reacts with HCl?? • Hydrogen gas is produced (popping noise we heard in earlier lab)

  12. Indicators • Substance that turns 1 color in acidic solutions and another in basic solutions. • Examples: phenolphthalein (used in bio) and litmus paper (made from a species of lichen)

  13. Acid-Base Reactions • Known as a neutralization reaction. Acids and bases will react with each other to form saltand water. A + B  Salt + H2O HCl + NaOH  NaCl + H2O

  14. Characteristics of Salts • Electrolytes • Ionic compounds • High melting points • Products of neutralization

  15. Arrhenius Definition Acid = substance that releases H+ ions in aq solution HCl  H+ + Cl- Base = substance that releases OH-ions in aq solution NaOH  Na+ + OH- Neutralize each other: H+ + OH-  H2O

  16. Bronsted-Lowry Definition As more and more substances were determined to have acidic or basic properties, even some without obvious H+ or OH-, a new definition was needed. • Acid = proton donor • Base = proton acceptor

  17. Bronsted-Lowry Definition • Acid = proton donor H2O + HCl  H3O+ + Cl-

  18. Bronsted-Lowry Definition • Base = proton acceptor NH3 + H2O  NH4+ + OH–

  19. When water gains a proton it is called HYDRONIUM. H3O+

  20. When water loses a proton it is called HYDROXIDE. OH-

  21. Acids & Bases Review • Acid • substance that releases H+ ions in aq solution • Proton donor • Base • substance that releases OH-ions in aq solution • Proton acceptor

  22. H2O is both an acid and a base Water is simultaneously donating and accepting protons = amphoteric substance

  23. Assignment • Bronsted-Lowry Acids & Bases WS • Titration Curve Data Graph

  24. Drill #9 5/5, 5/6/2014

  25. Homework Due • Bronsted-Lowry Acids & Bases WS • Keep Titration Graph

  26. Homework • Conjugate Acid-Base Pairs WS • 18-1 Review & Reinforcem

  27. Conjugate Acids & Bases • Conjugate acid – what is produced when a base gains a H+ ion • Conjugate base – what is produced when an acid loses a H+ ion • Conjugate base pair – two substances related to each other by the donating and accepting of a single H+ ion

  28. Conjugate acid-base pairs HF + H2O H3O + F – acid base conjugate conjugate acid base

  29. Objectives • SWBAT compare the strength of a weak acid with the strength of its conjugate base • SWBAT explain the relationship between acid and base strength and the values of their ionization constants.

  30. Acid Strength A stronger acid will react completely to form ions (strong electrolytes) and hydronium ions (H3O+) in water. Hydrochloric acid (all HCL molecules are ionized into hydronium and chloride ions) HCl + H2O H3O+ + Cl- Acetic Acid (not all A.A. molecules are ionized into hydronium and ions) CH3COOH + H2O H3O+ + CH3COO-

  31. Examples of Strong & Weak Acids StrongWeak HCl CH3COOH HBr H2CO3 H2SO4 HClO

  32. Base Strength • A strong base has the strongest affinity for H+ ions and dissociates entirely into metal ions and OH-. • For ex. Calcium oxide (CaO); oxygen strongly attracts H+ ions. • Strong bases: CaO, NaOH, KOH • Weak base: ammonia (NH3)

  33. Conjugate Pairs Inverse Relationship • The stronger the acid, the weaker its conjugate base • The stronger the base, the weaker its conjugate acid HCO3 + H2O  H3O + CO3 weak A strong B weak strong C.A. C.B.

  34. Sample Problem • Write an equation to show the dissociation of hydrochloric acid in water.

  35. Answer HCl + H2O →H3O+ + Cl− • HCl is a STRONG ACID

  36. Sample Problem • Write an equation to show the dissociation of the hydrogen carbonate ion in water.

  37. Answer HCO3 + H2O  H3O+ + CO3- • The hydrogen carbonate ion (HCO3-) is a WEAK ACID

  38. How can the strength of an acid or base be quantified? Measure the amount of hydronium ions created (acids) or the amount of hydroxide ions created (bases) by calculating dissociation constants.

  39. Acid Dissociation Constant HA + H2O  H3O+ + A- HA = acid (H = hydrogen, A = rest of acid molecule A = rest of acid after H+ is removed [ ] = concentration Ka = [H3O +] [A-] [HA]

  40. Acid Dissociation Constant • For HClO2,show the dissociation Rx and write the expression for it in terms of Ka • HClO2+ H2O ClO2 -+ H3O+ Ka = [H3O +] [A-] Ka = [H3O +] [ClO2 -] [HA] [HClO2]

  41. Your Turn • For HNO2 show the dissociation Rx and write the expression for it in terms of Ka • HNO2 + H2O  NO2 -+ H3O+ Ka = [H3O +] [A-] Ka = [H3O +] [NO2 -] [HA] [HNO2]

  42. Acid Dissociation Constant • The larger the dissociation value, the more the acid reacts with water to produce hydronium ions, therefore the stronger the acid • Weak acids have values less than 1 (only small fraction of acid molecule dissociates in water)

  43. Base Dissociation Constant B + H2O  HB+ + OH- B = base HB = B after H+ is added [ ] = concentration Kb = [HB+] [OH-] [B]

  44. Base Dissociation Constant • For C6H13NH2, show the dissociation Rx and write the expression for it in terms of Ka C6H13NH2+ H2O C6H13NH3++OH - Kb = [HB+] [OH-] Kb = [C6H13NH3+][OH-] [B] [C6H13NH2]

  45. Your Turn • For HSO3-, show the dissociation Rx and write the expression for it in terms of Ka HSO3-+ H2O +H2SO3 +OH - Kb = [HB+] [OH-] Kb = [H2SO3] [OH-] [B] [HSO3- ]

  46. Base Dissociation Constant • The stronger the base, the larger the concentration of OH- ions and the larger the Kb. • Weak bases have a Kb less than 1.

  47. Acid & Bases Lab: Litmus Test • Predict if substance is acidic, basic or neutral and record in 2nd column of WS. • Show me your predictions before going to lab. • Test the 18 substances using red and blue litmus paper. Record your results in columns 3 & 4 of table by placing a  under a category if acidic or basic. If no reaction, no . Place used litmus papers on paper towel on top of runway. • Show me your work before conducting pH test.

  48. Acid & Bases Lab: pH Test • For each substance, record the color that the pH paper changed to after you dipped it into the solution. • Record the pH value that matches with the color on the pH paper.

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