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Chemistry - Grade 12 4U > Acids and Bases > Flashcards

Acids and Bases Flashcards

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1
Q

Bronsted-Lowry Theory

A
  • Focusses on the transfer of H+ during rxn
  • Acids donate H+, bases accept (or proton)
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2
Q

Conjugate Pairs

A
  • An acid can only donate if there is a base acceptor
  • Conjugate pairs will only differ by one proton
    ex. HA + B -> A- + BH+
    HA acid -> A- base, B base -> BH+ acid
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3
Q

Amphiprotic Substances

A
  • Acts like an acid or base
  • For BL acid, must dissociate and release H+
  • For BL base, must accept H+ and have a lp
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4
Q

Properties of Acid and Bases

A

Alkali: soluble base, usually releases OH-
Salt: Ionic compound formed when H+ is replaced with another positive ion

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5
Q

Types of Acid-Base Reactions

A
  1. Acid + Base -> Salt + H2O
  2. Metal + Acid -> Salt + H2
  3. Acid + Carbonate -> Salt +H2O + CO2
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6
Q

the pH scale

A
  • Acidity or alkalinity related to concentration of H+ and OH- respectively
  • pH = -log[H+], [H+] = 10^-pH, small number implies base
  • Change in 1pH => change in [H+] x10, small pH change => large H+ change
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7
Q

Calculation involving Acids and Bases

A
  • rare product of water
  • ex. Kc = [H+] [OH-] /[H2O]
  • [H2O] remains constants so,
    [H2O] x Kc = [H+] [OH-]
    Kw = [H+] [OH-]
  • Increase in temp favours right side, both [] increase, pH decreases
  • Kw = -log[H+]
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8
Q

Concentrations in relation to pH

A

[H+] > [OH-] => acidic =. pH < 7
[H+] = [OH-] => neutral = ph=7
[H+] < [OH-] => basic = ph>7

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9
Q

pOH

A
  • pOH = -log[OH-]
    [OH-] = 10^-pOH
  • pKw = -log[OH-]
  • pH and pOH are inversely related
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10
Q

Acid Deposition

A
  • Acid Rain
  • Rain typically is 5.6 pH, acid rain is less due to SO2 and N oxides
  • Physical cleaning prior to combustion removes 80-90% of inorganic S
  • CaO reacts with SO2 to remove it after combustion
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11
Q

pH curves

A
  • Result of a titration, controlled neutralization
  • Plot of pH v. V of added reactant
  • Can be found using probes or calculations
    1. Strong A + Strong B: equivalence point of 7
    2. Weak A + Strong B : has a buffer, equivalence point greater than 7
    3. Strong A + Weak B: buffer zone, equivalence point less than 7
    4. Weak +Weak: buffer zone, approximately 7
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12
Q

Strong and Weak Acids

A

Strong: react almost completely, high conductivity, HCl, HNO3, H2SO4, HClO4
Weak: hardly reacts, low conductivity, a []ed weak A may have more H+ than a dilute strong acid

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13
Q

Strong and Weak Bases

A

Strong: react almost completely, high conductivity, Group 1 and 2 hydroxides
Weak: hardly reacts, low conductivity

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14
Q

Lewis Acids and Bases

A

Acids: e- pair acceptors
Bases: e- pair donors
- Lewis A-B rxns always result in both e- from a base
- Uses when something can only be described by Lewis

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15
Q

Transition metals and Ligands

A

Transition Metals: form ions with vacant d-sublevel orbitals, act as a lewis acid (electrophile)
Ligands: uses lp to form a dative bond with a metal ion, act as a lewis base (nucleophile)

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16
Q

Dissociation Constants

A
  • Kc becomes Ka, acid dissociation constant, proportional to [H3O+]
  • [H3O+] = [A-] (1:1)
  • Kc becomes Kb, base dissociation constant, proportional to [OH-]
  • [OH-] = [BH+]
17
Q

pKa and pKb

A
  • pKa = -logKa
  • pKb = -logKb
  • Inversely related
  • Chnage in 1 pKa/b = 10x change in Ka/b
18
Q

Kw calculations

A
  • Ka x Kb = Kw
  • -log(Ka x Kb) = -logKw
19
Q

Buffers

A
  • Aqueous solutions resistant to pH changes when a small amount of A/B is added
  • Messes with equilibrium, shifts significantly in either direction
  • [A-] = [HA]
  • [BH+] = [B]
20
Q

Preparing a Buffer

A
  1. Neutralize half of the weak A/B
  2. Adding a Conjugate salt
    - Adding an acid: increase H3O+ (shift left) and decrease OH- (right), pH restored
    - Adding a base: decrease H3O+(shift left) and increase OH- (right), pH restored
21
Q

Salt Hydrolisis

A

Cation from base and anion from acid forming an ionic compound, 4 cases
1. Strong A and B = neutral salt , pH close to 7
2. Weak A and Strong B = basic salt, pH > 7
3. Strong A and Weak B = acidic salt, pH < 7
4. Weak A and B = depends but mostly neutral

Chemistry - Grade 12 4U (7 decks)

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