Unit 14/15/16 – Acids, Bases & SaltsElectrolytes:

• 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

NaCl glycerol

• 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

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

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-

Symbolic representations

Solids (precipitates): (s), (c), ppt,

Ions: H+, H3O+, OH-, M+, Nm-, polyatomic + or –

Equilibrium:

Acids: chemical compounds that dissociate to H3O+ & Nm- (Arrhenius H+, Bronsted H3O+)

1. Donate H+ or H3O+ ions2. pH < 7 3. Corrosive

4. Caustic (eat away)

5. Toxic, Some poisonous (H3PO4, HF)6. React with metals7. Affect indicators 8. feel wet9. neutralize bases 10. Taste sour

- Mineral Acids contain H3O+ ions

1. HCl

2. HBr

3. HClO3

4. HClO4

5. HNO3

6. H2CO3

7. H2SO4

8. H3PO4

9. H2SeO4

- 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

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

Mineral Organic

1. LiOH 1. methanol- paint thinner

2. NaOH - lye 2. ethanol – medical

3. KOH 3. propanol – rubbing alcohol

4. RbOH 4. butanol

5. CsOH 5. pentanol

6. NH4OH-ammonia 6. hexanol

7. Mg(OH)2-mom 7. heptanol

8. Ca(OH)2-lime 8. octanol

9. Sr(OH)2 9. nonanol

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

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

Uses (H2SO4):

1. cellulose (film)

2. Fertilizers

3. Processing metal

4. Refining oil

Nitric acid – HNO3 (Dangerous, not in HS)

1. 68% pure (unstable), turn brown gradually

2. dilution 5:1 (water to acid)

3. Volatile 4. Spgr 1.42

Uses (HNO3):

1. Fertilizers 3. dyes

2. Explosives 4. plastics

Phosphoric acid – H3PO4

1. weak acid

2. dilution 2:1 (water to acid)

3. 88%

4. Spgr 1.87

Uses (H3PO4):

1. Fertilizers 3. rust proofing

2. detergents 4. phosphorous compounds

Acetic acid – HC2H3O2

1. Pungent

2. 99.8%

3. Dilution 8:1 (water to acid)

4. Spgr 1.05

Uses (HC2H3O2):

1. Plastics

2. Foods

3. Disinfectant in cleaning

Important Bases:

Lye – NaOH

1. Solid white 3. toxic

2. 97-98% 4. Spgr 1.06

Uses (NaOH):

1. Plastics 3. cellulose film

2. Soap 4. neutralize acid

Lime- Ca(OH)2:

1. Solid white 3. caustic

2. Toxic

Uses:

1.Water softner 3. plastics

2. Odor control 4. lawns

MOM – Mg(OH)2:

1. Solid white

2. Absorb CO2

3. Colloid

Uses:

1. Neutralize acids

2. Stomach upsets (anti acids)

3. Sunburns

Properties of Electrolytes:Acids:

1. Electrolytes H3O+

2. Dissociate completely3. Single HOH4. Dangerous even dilutedBases:1. Electrolytes OH-

2. Dissociate completely3. Single HOH4. Dangerous even diluted

Weak Electrolytes:

Acid/Base/Salt:

1. Weak acids and bases

2. Partially ionize

3. Minimum caustic but may be toxic

4. Equilibrium

Examples:

Strong Acids:

1. HCl 2. HBr 3. HI 4. HNO3

5. HClO3 6. HClO4 7. H2SO4 8. H2SeO4

Strong Bases:

1. NaOH 2. KOH 3. CsOH

4. Ca(OH)2 5. Sr(OH)2 6. Ba(OH)2

Weak Acid/Base/Salt:

1. H3PO4 2. H2CO3 3. HC2H3O2

4. LiOH 5. Mg(OH)2 6. Zn(OH)2

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

Conjugate pairs: the species that remain after an acid/base given up/taken on a proton.

Ex:

weaker weaker stronger stronger

1. HC2H3O2 + HOH H3O+ + C2H3O2-

acid base acid base

stronger stronger weak weak

2. HClO4 + HOH H3O+ + ClO4-

acid base acid base

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

Acid/Base Reaction:

Acid:

1. A + B Salt + HOH

2. A + Carbonate Salt + HOH + CO2

3. A + metal Salt + H2

4. HOH + nonmetal oxide Acid

Base:

1. B + nonmetal oxide Salt + HOH

2. HOH + metal oxide B

Salt:

1. Metal oxide + nonmetal oxide Salt

Protic acids:

1. 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

Self Ionization: 2 water molecules

HOH + HOH H3O+ + OH-

Power of Hydrogen

Definition: negative log of [H3O+]

1. Vinegar pH – 2.8

2. Distilled waterpH – 7.0

3. MOM pH – 10.5

Hydronium: H3O+ Hydroxide: OH-

Strong Acids Strong Bases

1. HCl 1. NaOH

2. HBr 2. KOH

3. HI 3. CsOH

4. HNO3 4. Ca(OH)2

5. HClO4 5. Sr(OH)2

6. HClO3 6. RbOH

7. H2SO4 7. Ba(OH)2

8. H2SeO4

Calculating pH

Formula: pH = - log [H3O+]

Calculating pOH

Formula: pOH = -log [OH-]

-Log [ H3O+]+ -Log [OH-] = 14

Scale:

Acid neutral bases

0 7 14

Indicators ColorsName 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

9.phenolphthalein colorless pink red10.thymolphthalein colorless pale bl blue11.alizarin yellow yellow orange red

Transition interval (pH) - above indicators:1. 0.0 -1.6 7. 6.0 - 7.62. 2.9 - 4.0 8. 6.6 - 8.03. 3.0 - 4.6 9. 8.2 - 10.64. 3.2 - 4.4 10. 9.4 - 10.65. 4.8 - 6.0 11. 10.0 - 12.06. 5.5 - 8.0

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)

Choosing Indicators:1. SA-/SB+ BB neutral2. SA-/WB+ MO acidic3. WA-/SB+ phth basic4. WA-/WB+ noneEquivalency point & titration: pH curve slow/

fast/ slow

rapid step [H3O+]=[OH-]

End point and neutralizationA + B S + HOH