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Chapter 14

Chapter 14. Acids and Bases. Naming Acids. 2 types of acids Binary ternary (sometimes called oxy) binary - H and one other type of atom name them hydro _________ ic acid. Naming Acids. Ex1 HCl Hydrochloric Acid Ex2 HBr Hydrobromic Acid Ex3 H 3 P Hydrophosphoric Acid.

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Chapter 14

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  1. Chapter 14 Acids and Bases

  2. Naming Acids • 2 types of acids • Binary • ternary (sometimes called oxy) • binary -H and one other type of atom • name them hydro _________ ic acid

  3. Naming Acids • Ex1 HCl • Hydrochloric Acid • Ex2 HBr • Hydrobromic Acid • Ex3 H3P • Hydrophosphoric Acid

  4. Writing formulas from names for Acids • Criss Cross charges • Ex4 Hydronitric Acid • H3N • Ex5 Hydrosulfuric Acid • H2S

  5. Naming Acids • ternary (oxy) acids • H with a polyatomic ion • Do not start with Hydro- • Change the –ate ending to –ic • Change the – ite ending to –ous

  6. Naming Acids • Ex6 H2SO4 • Sulfuric Acid • Ex7 H2SO3 • Sulfurous Acid • Ex8 HClO4 • Perchloric Acid • Ex9 HClO • Hypochlorous Acid

  7. Writing Formulas From Names • Ex10 Nitric Acid • HNO3 • Ex11 Phosphorous Acid • H3PO3

  8. Some common acids: • Sulfuric – used for fertilizer, petroleum, production of metal, paper, paint • HCl – stomach acid, food processing, iron, steel • Acetic acid – vinegar, fungicide, produced by fermentation • Nitric acid – explosives, rubber, plastics, dyes, drugs • Phosphoric acid – beverage flavoring, animal feed, detergents

  9. Properties of Acids: • Acid comes from Latin meaning acidus, or sour tasting. • Affect the colors of indicators. An indicator is a chemical that shows one color in an acid and another in a base. Acids turn blue litmus red.

  10. Properties of Acids: • Acids react with bases to produce salt and water. This is called neutralization. • HCl(aq) + NaOH(aq) NaCl(aq) + HOH (l) • 3H2SO4(aq)+ 2Al(OH)3(aq)  Al2(SO4)3(aq) + 6 HOH (aq)

  11. Properties of Acids: • Acids ionize in water. So, they conduct electricity (electrolytes). • Acids react with active metals to produce salts and hydrogen. • Mg+ + 2 HCl (aq) MgCl 2(aq) + H 2(g) • Cu(s) + HCl(aq)  NR

  12. Arrhenius Acids • Substances that produces H+ ions when mixed with water. • HCl(g) + H2O(l) H+1(aq) + Cl-1 (aq) • It is now found that: • H+1(aq) + H2O(l) H3O+1 (aq) • so it is really… • HCl(g) + H2O(l) H3O+1 (aq) + Cl-1 (aq)

  13. Definitions of Acids • Bronsted-Lowery Acids – proton donors • Show HCl + water and HCl + ammonia • HCl + H2O  H3O+(aq) + Cl-1(aq) • HCl + NH3 NH4+(aq) + Cl-1(aq) (*not Cl2!!)

  14. Types of Acids • Strong - HI, HBr, HCl, HNO3, H2SO4, HClO4 (one way arrows always!) • HBr + H2O  H3O+ (aq)+ Br-1 (aq) • Weak – HF, H2PO4, H2CO3, H2PO4 (double arrows always!) • HF (aq) + H2O (l) H3O+1 (aq) + F-1 (aq)

  15. Molecular, Total Ionic, and Net Ionic Equations for acids: • Molecular Equation: • Zn(s) + 2 HCl(aq) ZnCl2(aq) + H 2(g) • Total Ionic Equation: • Zn(s) + 2H+1(aq) + 2Cl-1 (aq) Zn+2(aq) + 2Cl-1(aq) + H2(g) • Net Ionic Equation: • Zn(s) + 2H+1(aq) Zn+2(aq) + H2(g)

  16. Some acids donate more than 1 proton…. • Monoprotic (HF) - an acid that donates one proton (one hydrogen) • Ex1: Write the reaction(s) showing the complete ionization of HF. • HF (aq) + H2O (l) H3O+1 (aq) + F-1 (aq)

  17. Some acids donate more than 1 proton…. • Diprotic (H2SO4) - an acid that donates two protons (two hydrogens) • Ex2: Write the reaction(s) showing the complete ionization of H2SO4. • H2SO4 (aq) + H2O (l) H3O+1(aq) + HSO4-1 (aq) • HSO4-1 (aq) + H2O(l) H3O+1(aq) + SO4-2 (aq) __________________________________ H2SO4 (aq) + 2 H2O(l) 2 H3O +1(aq)+SO4-2(aq) *Note: When you lose a H+1, you gain a negative.

  18. Some acids donate more than 1 proton…. • Triprotic Acid: an acid that donates three protons (three hydrogens). • Ex3: Write the reaction(s) showing the complete ionization of H3PO4. • H3PO 4(aq) + H2O (l) H3O +1(aq) + H2PO4 -1(aq) • H2PO4 -1(aq) + H2O (l) H3O +1(aq) + HPO4 -2(aq) • HPO4 -2 (aq) + H2O (l) H3O +1(aq) + PO4 -3(aq) ________________________________________ H3PO 4(aq) + 3 H2O (l) 3 H3O +1(aq) + PO4 -3(aq)

  19. Some acids donate more than 1 proton…. • Diprotic and Triprotic can also be referred to as polyprotic. • 2nd and 3rd ionizations are always weak (so, ).

  20. Bases • Bases are used in cleaners (floors, drains, ovens), react with fats and oils so they become water soluble, used to neutralize stomach acid (antacids), used as laxatives

  21. Properties of Bases • Bases are electrolytes. They dissociate in water. NaOH and KOH are strong electrolytes because they are both highly soluble. • Affect the colors of indicators. An indicator is a chemical that shows one color in an acid and another in a base. Bases turn red litmus blue. • Bases react with acids to produce salt and water. This is called neutralization. • Bases taste bitter and feel slippery. Soap is an example of a base.

  22. Definition of Bases • A substance that has OH- ions. Bases dissociate in water to give OH- & positive metal ions.

  23. Types of Bases • Traditional Bases (Arrhenius) – a substance that contains hydroxide ions and dissociates to give hydroxide ions in water. • NaOH(s) + H2ONa+(aq) + OH-(aq) • Mg(OH)2(s) + H2O  Mg+2(aq) + 2OH-(aq)

  24. Types of Bases 2. Bronsted- Lowry bases – proton acceptors • NH3(g) + H2O(l)  NH4+1(aq) + OH-1(aq) * Water is amphoteric. It can act as an acid or base.

  25. Types of Bases Hydroxides of Column I and II are strong bases • List of strong bases: • NaOH, KOH, CsOH, Ca(OH)2 • List of weak bases: • many organic compounds with N…NH3, C6H5NH2, C2H3O2-

  26. Neutralization reactions – hydronium + hydroxide yields water • It is a type of double replacement reaction. • Note: H2O = HOH • Acid + Base → Salt and Water • General Formula: • HX + MOH  MX + H2O

  27. Neutralization Reaction • Example: hydrochloric acid + barium hydroxide ( molecular, total ionic, net ionic) • 2HCl(aq) + Ba(OH)2(aq) BaCl2(aq) + 2HOH(l) • 2H+1(aq) + 2Cl-1(aq) + Ba+2(aq) + 2OH-1(aq) Ba+2(aq) + 2Cl-1(aq) + 2HOH(l) • 2H+1(aq) + 2OH-1(aq) 2HOH(l)

  28. Relative Strengths of Acids and Bases • Some acids and bases are stronger than others. • Bronsted (Danish) and Lowry (English) independently discovered that acids are proton donors and bases are proton acceptors. A proton is a hydrogen ion.

  29. Relative Strengths of Acids and Bases • Strong Acid Example: • HCl(g) + H2O(l)  H3O+1(aq) + Cl-1(aq) (Acid) (Base) • Weak Base Example: • NH3(g)+ H2O(l)NH4+1(aq) + OH-1(aq) (Base) (Acid) Remember – water is amphoteric!

  30. Conjugate Acids & Bases • Conjugate Acid: the substance that was the base and now acts as an acid. • Conjugate Base: the substance that was the acid and now acts as a base. • HCl(g)+ H2O(l)  H3O+1(aq) + Cl-1(aq) (Acid) (Base)(Conjugate Acid) (Conjugate Base)

  31. Conjugate Acids & Bases • NH3(g)+ H2O(l)  NH4+1(aq) + OH-1(aq) • HF(l)+ H2O(l) H3O+1(aq) + F-1(aq)

  32. Conjugate Acids and bases • H2CO3(aq)+ H2O(l)  H3O+1(aq) + HCO3-1(aq) • The stronger the acid, the weaker the conjugate base. • Proton transfer reactions favor the production of the weaker acid and the • weaker base.

  33. Conj. Acid/Base Practice • Complete the equation and label acid base pairs • HSO4-1(aq)+ HCO3-1(aq) • Write an equation showing how NH2-1 is a stronger base than HSO4-1

  34. Conj. Acid/Base Practice • Which one is correct? • HSO4-1(aq) + H3O+1(aq) H2SO4(aq)+ H2O(l) (Base) (Acid) (Conj. Acid) (Conj. Base) or • HSO4-1(aq) + OH-1(aq) SO4-2(aq)+ H2O(l) (Acid) (Base) (Conj. Base) (Conj. Acid) The second reaction is favored because a weaker conjugate acid/base is produced.

  35. Stuff to know for Acids and Bases • 2nd and 3rd ionizations are always weak. This means a double yield sign (). • Memorize these strong acids. Strong means a single yield sign (). • HI, HBr, HCl, HNO3, H2SO4, HClO4 • All other acids get double yield signs. • Strong bases include metals from column #1 and column #2 (below magnesium). • Proton reactions favor the formation of the weaker acid and base.

  36. Reactions of Acids and Bases • Neutralization (double replacement): • Acid + Base  Salt + Water • HX + MOH  MX + H2O • Ex1: • HCl(aq) + NaOH(aq)  NaCl(aq) + HOH(l)

  37. Reactions of Acids and Baes • Acid + Metal (single replacement): • Metal + Acid  Salt + Hydrogen • Ex2: • Mg(s) + 2 HCl(aq)  MgCl2(aq) + H2(g)

  38. Reactions of Acids and Bases • Acid in water: • Acid + Water  Hydronium Ion + Negative Ion • Ex3: • HCl(g) + H2O(l)  H3O+1(aq) + Cl-1(aq)

  39. Reactions of Acids and Bases • Traditional Base (ends with OH) in water (dissociation): • Base + Water  Positive Ion + Hydroxide • Ex4: • Fe(OH)3(s) + H2O(l) Fe+3(aq) + 3 OH-1(aq)

  40. Reactions of Acids and Bases • Formation of acids and bases from anhydrides - synthesis (anhydride “without water”): • Nonmetal oxide + water  acid • Ex5a: • CO2(g) + H2O(l) H2CO3(aq) • Ex5b: • SO3(g) + H2O(l) H2SO4(aq) • Note: just add the nonmetal oxide to the water to determine the product.

  41. Reactions of Acids and Bases • Metal oxide + water  base • Ex5c: • Na2O(s) + H2O(l) 2 NaOH(aq) • Ex5d: • MgO(s) + H2O(l) Mg(OH)2(aq)

  42. Reactions of Acids and Bases • Acid and metal oxide (really just an acid and a base): • Acid + Metal Oxide  Salt + Water • Ex6: • H2SO4(aq) + CuO(s)  • Turn CuO into Cu(OH)2 • H2SO4(aq) + Cu(OH)2 (aq) CuSO4(aq) + HOH(l) • Now, re-write the original reactants, new products, and balance. • H2SO4(aq) + CuO(s) CuSO4(aq) + H2O(l)

  43. Reactions of Acids and Bases • Base and nonmetal oxide (really just an acid and a base • Base + Nonmetal Oxide  Salt + Water • Ex7a: • CO2(g) + NaOH(aq) NaHCO3(aq)

  44. Reactions of Acids and Bases • This is a little confusing. So these reactions will be done like: • CO2(g) + NaOH(aq) • Turn CO2 into H2CO3 • H2CO3(aq) + NaOH(aq) Na2CO3(aq) + HOH(l) • Now, re-write the original reactants, new products, and balance. • CO2(g) + 2 NaOH(aq)  Na2CO3(aq) + H2O(l)

  45. Reactions of Acids and Bases • Ex7b: • 2 CO2(g) + Ca(OH)2(aq) Ca(HCO3)2(aq) • CO2(g) + Ca(OH)2(aq) • Turn CO2 into H2CO3 • H2CO3(aq) + Ca(OH)2(aq) CaCO3(aq) + HOH(l) • Now, re-write the original reactants, new products, and balance. • CO2(g) + Ca(OH)2(aq) CaCO3(aq) + H2O(l)

  46. Reactions of Acids and Bases • Metal oxide and nonmetal oxide • It is like an acid base reaction they yield salt. However, it does not produce water since no hydrogen is involved. • Ex8a: • MgO(s) + CO2(g)  MgCO3(s) • Note: just add the nonmetal oxide to the metal oxide to determine the product. • Ex8b: • CuO(s) + SO3(g) CuSO4(s)

  47. Aqueous Solutions and the Concept of pH • Tap water conducts electricity – why? – many ions present: • examples: • Distilled water appears to not conduct electricity, but it does – just a little, tiny bit • H2O + H2O  H3O+1 + OH-1

  48. Aqueous Solutions and the Concept of pH • The normal way to express the quantity of hydronium and hydroxide ions is in moles/L (M) • At 25 C0, [H3O+1] = 1 x 10-7 so [OH-1] = 1 x 10-7 • These numbers are constant in neutral solution, so we can multiply them to get a constant • We call this constant Kw - ionization constant for water • Kw = [H3O+1][OH-1]

  49. Aqueous Solutions and the Concept of pH • At 25 C0, [H3O+1] = 1 x 10-7 so [OH-1] = 1 x 10-7 so Kw = 1 x 10-14 • Example: If the [H3O+1] is 1 x 10-3M, then what is the [OH-1]? • The solution is acidic because the hydronium ion concentration is greaterthanthe hydroxide concentration.

  50. Kw Practice Fill in the table below:

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