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
• 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
H 3O +
(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+ + ClBases: NaOH
Na+ + OHSalts: 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+ 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
- 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 OH1. 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
11. Al(OH)3
12. Zn(OH)2
10. decanol
11. ethyl glycol- anti freeze
12. glycerol – medical syrup
Important acids:
Hydrochloric acid – HCl
Extremely soluble in HOH
dilution 4:1
35% strong acid
Specific 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
2. Explosives
3. dyes
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
2. detergents
3. rust proofing
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
2. 97-98%
3. toxic
4. Spgr 1.06
Uses (NaOH):
1. Plastics
2. Soap
Lime- Ca(OH)2:
1. Solid white
2. Toxic
Uses:
1.Water softner
2. Odor control
3. cellulose film
4. neutralize acid
3. caustic
3. plastics
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 completely
3. Single
HOH
4. Dangerous even diluted
Bases:
1. Electrolytes OH2. Dissociate completely
3. Single
HOH
4. 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
4. Ca(OH)2 5. Sr(OH)2
3. CsOH
6. Ba(OH)2
Weak Acid/Base/Salt:
1. H3PO4
2. H2CO3
4. LiOH
5. Mg(OH)2
3. HC2H3O2
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
1. HC2H3O2 + HOH
acid
base
stronger
stronger
2. HClO4 + HOH
acid
base
stronger stronger
H3O+ + C2H3O2acid
base
weak
weak
H3O+ + ClO4acid
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
2. HOH + metal oxide
B
Salt:
1. Metal oxide + nonmetal oxide
Salt + HOH
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+ + OHPower of Hydrogen
Definition: negative log of [H3O+]
1. Vinegar
pH – 2.8
2. Distilled water pH – 7.0
3. MOM
pH – 10.5
Hydronium: H3O+ Hydroxide: OH-
Strong Acids
1. HCl
2. HBr
3. HI
4. HNO3
5. HClO4
6. HClO3
7. H2SO4
8. H2SeO4
Strong Bases
1. NaOH
2. KOH
3. CsOH
4. Ca(OH)2
5. Sr(OH)2
6. RbOH
7. Ba(OH)2
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 Colors
Name
Acidic
Transition
1.methyl violet
2.methyl yellow
3.bromphenol blue
4.methyl orange
5.methyl red
6.litmus
7.bromthymol blue
8.phenol red
yellow
red
yellow
red
red
red
yellow
yellow
aqua
orange
green
orange
buff
pink
green
orange
Alkaline
blue
yellow
blue
yellow
yellow
blue
blue
red
9.phenolphthalein colorless pink
10.thymolphthalein colorless pale bl
11.alizarin yellow yellow
orange
red
blue
red
Transition interval (pH) - above indicators:
1. 0.0 -1.6
7. 6.0 - 7.6
2. 2.9 - 4.0
8. 6.6 - 8.0
3. 3.0 - 4.6
9. 8.2 - 10.6
4. 3.2 - 4.4
10. 9.4 - 10.6
5. 4.8 - 6.0
11. 10.0 - 12.0
6. 5.5 - 8.0
Important Indicators:
• Litmus
• Phenolphthalein
• Bromthymol blue
4. methyl orange
5. phenol red
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 neutral
2. SA-/WB+
MO acidic
3. WA-/SB+
phth basic
4. WA-/WB+
none
Equivalency point & titration: pH curve slow/
fast/ slow
rapid step [H3O+]=[OH-]
End point and neutralization
A+B
S + HOH