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Unit 14/15/16 – Acids, Bases & Salts

Unit 14/15/16 – Acids, Bases & Salts. Electrolytes: Faraday: defined electrolytes/ nonelectrolytes Electrolytes Non electrolytes 1. conduct elect. 1. non conductor 2. ions + & - 2. molecules (neutral) 3. cation +, anion - 3. organic (covalent) Ex: HCl Ex: alcohol

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Unit 14/15/16 – Acids, Bases & Salts

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  1. Unit 14/15/16 – Acids, Bases & Salts Electrolytes: • Faraday: defined electrolytes/ nonelectrolytes Electrolytes Non electrolytes 1. conduct elect. 1. non conductor 2. ions + & - 2. molecules (neutral) 3. cation +, anion - 3. organic (covalent) Ex: HCl Ex: alcohol NaOH sugar glycerol NaCl

  2. Arrhenius: defined Acid/Base/Salt as made of Ions 1. Acids: H+ (hydrogen ions) 2. Bases: OH- (hydroxide ions) 3. Salts: made of + ions (mostly metals) and -- ions (not OH-) • Bronsted –Lowrey: ions in aqueous solution 1. Acids: H3O+ ; H+ + HOH H3O+ (hydronium ion) proton donor

  3. 2. Bases: OH- (hydroxide ion) proton acceptor 3. Salts: + cation & - anion, (no OH-) • Lewis: broadest definition – e- pair exchange 1. Acids: electron pair acceptors 2. Bases: electron pair donors 3. Salts: + cations & - anions, no constraints

  4. Dissociation of ionic compounds: falls apart, strong electrolytes in HOH solution (aqueous) Ionization of ionic compounds: Pulled (ripped) apart by HOH in aqueous solution, weak electrolytes Examples: Acids: HCl H3O+ + Cl- Bases: NaOH Na+ + OH- Salts: NaCl Na+ + Cl-

  5. Symbolic representations Solids (precipitates): (s), (c), ppt, Ions: H+, H3O+, OH-, M+, Nm-, polyatomic + or – Equilibrium:

  6. Acids: chemical compounds that dissociate to H3O+ & Nm- (Arrhenius H+, Bronsted H3O+) 1. Donate H+ or H3O+ ions 2. pH < 7 3. Corrosive 4. Caustic (eat away) 5. Toxic, Some poisonous (H3PO4, HF) 6. React with metals 7. Affect indicators 8. feel wet 9. neutralize bases 10. Taste sour

  7. - Mineral Acids contain H3O+ ions 1. HCl 2. HBr 3. HClO3 4. HClO4 5. HNO3 6. H2CO3 7. H2SO4 8. H3PO4 9. H2SeO4

  8. - Organic (carboxyl) acids contain COOH-- 1. Formic acid – produced by red ants 2. Citric acid – grapefruits, oranges 3. Ascorbic acid – tomato, vitamin C 4. Lactic acid - milk 5. Buteric acid – rancid butter, cheese 6. Acetic acid – fruits, grains - vinegar 7. Malic acid – apples, pears 8. Acetylsalicylic –willow tree bark aspirin 9. Oxalic –sorrel plant

  9. Bases: chemical compounds that dissociate to M+ and OH- 1. Hydroxide (OH-) ions 2. pH > 7 3. Slippery feeling 4. Affect indicators 5. Neutralize acids 6. toxic 7. electrolytes 8. corrosive (metals) 9. caustic (skin) 10. Bitter taste

  10. Mineral Organic • LiOH 1. methanol- paint thinner • NaOH - lye 2. ethanol – medical • KOH 3. propanol – rubbing alcohol • RbOH 4. butanol • CsOH 5. pentanol • NH4OH-ammonia 6. hexanol • Mg(OH)2-mom 7. heptanol • Ca(OH)2-lime 8. octanol • Sr(OH)2 9. nonanol

  11. 10. Ba(OH)2 10. decanol 11. Al(OH)3 11. ethyl glycol- anti freeze 12. Zn(OH)2 12. glycerol – medical syrup Important acids:Hydrochloric acid – HClExtremely soluble in HOH dilution 4:135% strong acidSpecific gravity 1.20

  12. Uses (HCl): 1. Pickling metals (purify steel) 2. Preparation for Mg 3. Cleaning Sulfuric acid – H2SO4 1. 95 to 98% pure 2. dense, oily 3. dilution 6:1(water to acid) 4. Spgr 1.84

  13. Uses (H2SO4): 1. cellulose (film) 2. Fertilizers • Processing metal • Refining oil Nitric acid – HNO3 (Dangerous, not in HS) • 68% pure (unstable), turn brown gradually 2. dilution 5:1 (water to acid) 3. Volatile 4. Spgr 1.42

  14. Uses (HNO3): • Fertilizers 3. dyes • Explosives 4. plastics Phosphoric acid – H3PO4 • weak acid • dilution 2:1 (water to acid) • 88% • Spgr 1.87

  15. Uses (H3PO4): 1. Fertilizers 3. rust proofing 2. detergents 4. phosphorous compounds Acetic acid – HC2H3O2 • Pungent • 99.8% • Dilution 8:1 (water to acid) • Spgr 1.05

  16. Uses (HC2H3O2): • Plastics • Foods • Disinfectant in cleaning Important Bases: Lye – NaOH • Solid white 3. toxic • 97-98% 4. Spgr 1.06

  17. Uses (NaOH): • Plastics 3. cellulose film • Soap 4. neutralize acid Lime- Ca(OH)2: • Solid white 3. caustic • Toxic Uses: 1.Water softner 3. plastics 2. Odor control 4. lawns

  18. MOM – Mg(OH)2: • Solid white • Absorb CO2 • Colloid Uses: • Neutralize acids • Stomach upsets (anti acids) • Sunburns

  19. Properties of Electrolytes: Acids: • Electrolytes H3O+ • Dissociate completely • Single HOH • Dangerous even diluted Bases: • Electrolytes OH- • Dissociate completely • Single HOH • Dangerous even diluted

  20. Weak Electrolytes: Acid/Base/Salt: • Weak acids and bases • Partially ionize • Minimum caustic but may be toxic 4. Equilibrium Examples: Strong Acids: • HCl 2. HBr 3. HI 4. HNO3 5. HClO3 6. HClO4 7. H2SO4 8. H2SeO4

  21. Strong Bases: • NaOH 2. KOH 3. CsOH • Ca(OH)2 5. Sr(OH)2 6. Ba(OH)2 Weak Acid/Base/Salt: • H3PO4 2. H2CO3 3. HC2H3O2 • LiOH 5. Mg(OH)2 6. Zn(OH)2

  22. Anhydride: without HOH/ anhydrous Acid Anhydride: nonmetal oxide NmO Ex: CO2 + HOH H2CO3 SO2 + HOH H2SO3 Basic Anhydride: metal oxides MO(alkaline) Ex: K2O + HOH 2 KOH CaO + HOH Ca(OH)2

  23. Conjugate pairs: the species that remain after an acid/base given up/taken on a proton. Ex: weaker weaker stronger stronger • HC2H3O2 + HOH H3O+ + C2H3O2- acid base acid base stronger stronger weak weak 2. HClO4 + HOH H3O+ + ClO4- acid base acid base

  24. Amphoteric Compounds: maybe an acid or base depends on situation. Weak acid acts as a base, weak base acts as an acid, and weak/neutral acts as an acid or a base. Ex: A1(OH)3 Pb(OH)2 Sn(OH)2 Using the Periodic Chart for A/B/S Ex: 1. Li 2. Cl 3. Zn 4. Al 5. Sr 6. Br 7. Ag 8. Sn 9. K 10. S

  25. Acid/Base Reaction: Acid: • A + B Salt + HOH • A + Carbonate Salt + HOH + CO2 • A + metal Salt + H2 • HOH + nonmetal oxide Acid

  26. Base: • B + nonmetal oxide Salt + HOH • HOH + metal oxide B Salt: • Metal oxide + nonmetal oxide Salt

  27. Protic acids: • Monoprotic: one H+ proton HCl, HBr, HC2H3O2, HClO3, HNO3 2. Diprotic: 2 H+ H2SO4, H2CO3, H2SeO4, H2SO3, H2BrO3 3. Triprotic: 3 H+ H3PO3, H3PO4, H3AsO4

  28. Self Ionization: 2 water molecules HOH + HOH H3O+ + OH- Power of Hydrogen Definition: negative log of [H3O+] • Vinegar pH – 2.8 • Distilled water pH – 7.0 • MOM pH – 10.5 Hydronium: H3O+ Hydroxide: OH-

  29. Strong Acids Strong Bases • HCl 1. NaOH • HBr 2. KOH • HI 3. CsOH • HNO3 4. Ca(OH)2 • HClO4 5. Sr(OH)2 • HClO3 6. RbOH • H2SO4 7. Ba(OH)2 • H2SeO4

  30. Calculating pH Formula: pH = - log [H3O+] Calculating pOH Formula: pOH = -log [OH-] -Log [ H3O+]+ -Log [OH-] = 14 Scale: Acid neutral bases 0 7 14

  31. Indicators Colors Name Acidic Transition Alkaline 1.methyl violet yellow aqua blue 2.methyl yellow red orange yellow 3.bromphenol blue yellow green blue 4.methyl orange red orange yellow 5.methyl red red buff yellow 6.litmus red pink blue 7.bromthymol blue yellow green blue 8.phenol red yellow orange red

  32. 9.phenolphthalein colorless pink red 10.thymolphthalein colorless pale bl blue 11.alizarin yellow yellow orange red Transition interval (pH) - above indicators: • 0.0 -1.6 7. 6.0 - 7.6 • 2.9 - 4.0 8. 6.6 - 8.0 • 3.0 - 4.6 9. 8.2 - 10.6 • 3.2 - 4.4 10. 9.4 - 10.6 • 4.8 - 6.0 11. 10.0 - 12.0 • 5.5 - 8.0

  33. Important Indicators: • Litmus 4. methyl orange • Phenolphthalein 5. phenol red • Bromthymol blue 6. universal Indicator Mechanism: Indicators are weak acids. In the solution there are nonionized molecules HIn(red) H+ + In-(blue)

  34. Choosing Indicators: • SA-/SB+ BB neutral • SA-/WB+ MO acidic • WA-/SB+ phth basic • WA-/WB+ none Equivalency point & titration: pH curve slow/ fast/ slow rapid step [H3O+]=[OH-] End point and neutralization A + B S + HOH

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