1. Chapter 8
Acids and Bases
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2. Acids What is an Acid? Properties Classes of Acids Common Acids
Hydrogen ion, proton (H+) donor
Properties
Taste sour, reacts with metals, donates protons
Classes of Acids
Common Acids
Two classes of acids – organic acids and inorganic acids
Battery acid sulfuric acid
Stomach acid hydrochloric acid
Lemon juice citric acid, ascorbic acid
Vinegar acetic acid
Wine tartaric acid

4. HA(aq) + H2O(l)  H3O+(aq) + A-(aq)
Acid Reaction
물과의 반응
HA  H+ + A-
H+ + H2O  H3O+
HA(aq) + H2O(l)  H3O+(aq) + A-(aq)
Acids increase the hydronium ion concentration in water

5. Hydronium Ion

6. Types of Acids Strong Weak Acids that dissociate completely in water
Inorganic Acids
HCl, H2SO4, HNO3, HClO4
Weak
Acids that partially dissociate in water
Organic Acids
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7. Bases What is a base? Properties Common Bases Hydrogen ion acceptor
Hydroxide ion (OH-) and Ammonia (NH3)
Properties
Taste bitter, forms insoluble hydroxide with metals, accepts hydrogen ions
Common Bases
Baking Soda Sodium bicarbonate
Lye Sodium hydroxide
Quicklime (lime) calcium oxide
Ammonia organic base

9. BOH(aq)  B+(aq) + OH-(aq)
Base Reaction
Generic Reaction in Water
BOH  B+ + OH-
OH- + H2O  H2O + OH-
BOH(aq)  B+(aq) + OH-(aq)
Bases increase the hydroxide ion concentration

10. Chemical Equilibrium What determines strong vs weak?
The state in a reaction when there in no change in the concentration of the reactants or products
Reactions that proceed in both directions at the same time (rate)

11. Carbon Dioxide Carbon Dioxide, CO2 CO2 + H2O  H2CO3
H2CO3 + H2O  H3O+ + HCO3-
HCO H2O  H3O+ + CO3-2
H2CO H2O  2 H3O+ + CO3-2

13. Acid-Base Pairs Acid that loses a H+ becomes a base
Called conjugate base
H2CO3 + H2O  H3O+ + HCO3-
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14. Water H2O + H2O  H3O+ + OH- Auto protolysis Amphiprotic (Amphoteric)
substance that can behave as an acid or a base

15. Water [H+] = 1 x 10-7 mol/L [OH-] = 1 x 10-7 mol/L
Kw = [H+] x [OH-] = 1 x 10-14

16. pH Scale pH = - log [H+] pOH = - log [OH+] pH + pOH = 14
Concentration [H+] or [OH-]
pH = - log [H+]
pOH = - log [OH+]
What is the pH of neutral water?
pH + pOH = 14
Acidic pH < 7
Neutral pH = 7
Basic pH > 7

17. Conversions acidic/neutral /basic pH of common substances
Acidic pH < 7 [H+] > 1e-7
Neutral pH = 7
Basic pH > 7 [H+] < 1e-7
Battery acid pH 1.3 Blood pH
Lemon juice pH 2.3 Stomach Acid pH
Vinegar pH 2.5
Cheese pH
Baking soda pH 8.3
Detergents pH 10-11
Drain cleaner pH 13+
Borax pH 9.2

18. Measuring pH Meters Indicators Common Indicators
meter uses a standard electrode to measure the hydrogen ion concentration, [H+]
Indicators
Molecules that change color depending on the hydrogen ion concentration, [H+]
Common Indicators
Thymol blue pH range
Bromocresol green pH range
Phenol red pH range
Phenolphthalein pH range

19. Natural Indicators Anthocyanins found in flower, fruits and vegetables+ O H + O H
Pelargonidin (pink)
Cyanindin (violet)
Delphinidin (pale blue) + O H

20. Neutralization 중화 적정, Titration
process of adding acid or base to a solution to achieve a neutral solution, pH = 7
equal amounts of acid and base
적정, Titration
determination of the concentration of a solution by reaction with a solution of known concentration

22. Neutralization 당량점 Equivalence Point Mole Acid = Moles of Base
the point in a titration when equal portions of the reactants have been added (stoichiometry)
Mole Acid = Moles of Base
MAVA = MBVB

23. Buffers 완충용액, Buffers Example
chemical systems composed of acid-base pairs that resist changes in pH
buffers contain an acid-base pair which maintain the pH
Example
Acetic Acid and Sodium Acetate

24. Buffers
pH = pKa + log{[base form]/[acid form]}

25. Homework
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1, 5, 7, 23
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