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Acids, Bases & Salts

Acids, Bases & Salts

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Acids, Bases & Salts

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  1. Acids, Bases & Salts • Acid Properties: • Sour taste, react with metals to produce hydrogen gas, electrolytes, affect indicators (turns blue litmus paper to red)

  2. Acids, Bases & Salts • Base Properties: • Bitter taste, produce electrolytes, affect indicators (turns red litmus paper to blue)

  3. Acids • Electrolytes: substances that conduct electric current when dissolved in water.

  4. Acids • Indicators: chemical substances that change color based on acid concentration.

  5. Acids • Arrhenius Theory: acids produce H+ ions when dissolved (ionized) in water.

  6. Acids • Arrhenius Theory: bases produce OH- ions when dissolved (ionized) in water.

  7. Acids • Dissociation vs. ionization: dissociation is the separation of ions in solution. In ionization, neutral molecules react with water to form ions.

  8. Acids • Bronsted-Lowry Theory: acids donate protons (H+) in a chemical reaction. • Ex. HCl(g) + H2O(l) --> H3O+(aq) + Cl-(aq)

  9. Acids • The HCl gas donates a proton to the water molecule, producing the hydronium ion. HCl is considered an acid, water is considered a base.

  10. Acids • Bronsted-Lowry Theory: bases accept protons (H+) in a chemical reaction. • HCl and Cl- are considered a conjugate acid/base pair.

  11. Acids • Conjugate acid/base pairs: Conjugate base - the particle leftover after the acid donates a proton.

  12. Acids • Conjugate acid/base pairs: Conjugate acid - the particle produced after the base accepts the proton.

  13. Acids • Identify the acid, base, conjugate base and conjugate acid in the following: HNO3(aq) + NaOH(aq) --> H2O(l) + NaNO3(aq).

  14. Acids • Practice problems #1-2, p. 576. • What do you want to know?

  15. Acids • Lewis Theory: an acid is any substance that accepts an electron pair. A base is any substance that donates an electron pair. • NH3 + BF3 --> NH3BF3

  16. Acids • Use electron dot diagrams to determine if a substance is a Lewis acid or base. • Ex. Classify Cl- as a Lewis acid or base.

  17. Acids • Coordination complexes: molecular ligands (attachments) approach a metal cation and bond using secondary (d-orbital) valance.

  18. Acids • Complex ion formation: ex. Ag+ + NH3 --> ? (coordination number of 2).

  19. Acids • What is the name of [CoCl2(NH3)5]Br • Practice Problems #3-8, p. 578. Any questions?

  20. Acid Nomenclature • Binary acids: acids consisting of 2 elements. • Ex. HCl • HI • HBr

  21. Acid Nomenclature • Ternary Acids and Bases: acids or bases containing three elements. • Common ternary acid - formed by using H+ and a common polyatomic ion.

  22. Acid Nomenclature • Use the polyatomic name and the suffix -ic. • Ex. H2SO4 • HNO3 • HClO3

  23. Acid Nomenclature • A ternary acid that is the same as the common acid but with one less oxygen uses the suffix -ous. • Ex. H2SO3 • HClO2

  24. Acid Nomenclature • A ternary acid that is the same as the common acid but with two less oxygens uses the prefix -hypo and the suffix -ous. • Ex. HClO

  25. Acid Nomenclature • A ternary acid that is the same as the common acid but with one more oxygen uses the prefix -per and the suffix -ic. • Ex. HClO4

  26. Acid Nomenclature • Common ternary base - formed by using metal and the hydroxide polyatomic ion. • Ex. NaOH, Mg(OH)2

  27. Acid Nomenclature • Organic acids: carboxylic acids, -COOH • Name the chain and add -oic acid.

  28. Acid Nomenclature • Practice Problems #9-13, p. 580 • Wha?

  29. Acid/Base Behavior • Consider a compound in the form HOX. If X is very electronegative then the H is given up as a proton and it acts as an acid. If not it acts as a base.

  30. Acid/Base Behavior • So, nonmetals tend to form acids, metals tend to form bases when dissolved in water. • Ex. MgO • CO

  31. Acid/Base Behavior • Acidic and Basic Anhydrides: acids and bases that have had water removed. • Ex. Acid anhydride + water --> acid

  32. Acid/Base Behavior • Ex. Acid anhydride + water --> acid • SO2 + H2O --> H2SO3

  33. Acid/Base Behavior • Ex. basic anhydride + water --> base • Na2O + H2O --> 2 NaOH • Practice problems #14-15 p. 583

  34. Acid/Base Behavior • Acid base strength: not all acids complete ionize in water. That is a lot of the acid or base molecules remain unreacted. • Ex. Ammonia (weak base)

  35. Acid/Base Behavior • Concept review #16-19 p. 584

  36. Salts and Solutions • Salt : an ionic compound that does not consist of H+ or OH- • Ex. KCl, MgO (any ionic compound that is not an Arrehnius acid or base)

  37. Neutralization • Neutralization reaction: a acid reacts with a base to produce a salt and water. • Really just a double displacement reaction

  38. Neutralization • Ex. Produce the products and balance the equation for the reaction of the acid HCl and the base AgOH.

  39. Neutralization • Naming salts - who cares? • Ex. Sodium hydrogen carbonate • Ex. Sodium dihydrogen phosphate

  40. Net Ionic Equations • Some ions in a neutralization reaction are considered spectator ions. That is, they are unchanged after the reaction.

  41. Net Ionic Equations • Chemists often write net ionic equations to show only those ions that actually take place in the reaction. Ex. HCl + NaOH

  42. Net Ionic Equations • Polyprotic acids - go through two steps of ionization • Ex. Sulfuric acid

  43. Net Ionic Equations • The binary acids HCl, HBr, and HI are strong acids, the rest are weak. • Ternary acids with 2 or more oxygens versus hydrogens are strong.

  44. Net Ionic Equations • Organic acids are weak. • Polyprotic acids: second step always results in a weak acid • Group 1 and 2 bases are strong.

  45. Net Ionic Equations • Molecules and weak acids and bases are not written in ionic form. • Salts are written in ionic form, oxides and gases are written as molecules.

  46. Net Ionic Equations • Practice problems #23-27 p. 590. (in groups - 15 minutes)

  47. Ionization Constant • The Keq for the ionization of a weak acid or base determines the extent that [H3O+] or [OH-] ions will be produced at equilibrium.

  48. Ionization Constant • Ka is the ionization constant of a weak acid. HX + H2O <--> H3O+ + X-. • What is Ka for this reaction?

  49. Ionization Constant • Kb is the ionization constant of a weak base. NH3+ H2O <--> NH4+ + OH-. • What is Kb for this reaction?

  50. Ionization Constant • Percent ionization = [amount ionized] / [original acid] x 100% • Problems 28-31, p. 592-593