Acids, Bases & Oxides Flashcards

1
Q

What is an Arrhenius / ionic acid?

A

A substance when dissolved in water, ionises to produce hydrogen ions.

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2
Q

What is an Arrhenius / ionic base?

A

A substance when dissolved in water, ionises to produce hydroxide ions.

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3
Q

What are 2 limitations of Arrhenius / ionic theory?

A
  1. since acids and bases dissolved to produce H+ or OH- ions, they must contain those ions.

–> ammonia is weak base, but it does not contain OH-. it dissolves in water to produce OH-.

NH3 + H2O ⇌ (NH4)+ + OH-

  1. cannot explain acid-base reactions that do not produce water.

HCl + NH3 –> NH4Cl

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4
Q

What is a Bronsted-Lowry / proton transfer theory acid?

A

A substance that is capable of donating a proton

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5
Q

What is a Bronsted-Lowry / proton transfer theory base?

A

A substance that is capable of accepting a proton

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6
Q

What is a limitation of BL / proton transfer theory?

A
  1. cannot explain acid-base reactions that do not involve hydrogen transfer.

BF3 + NH3 —> NH3BF3

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7
Q

Explain conjugate acid

A

[Bronsted-Lowry / Proton transfer theory]

Since a BL base receives a proton to form an ion, the ion can donate a proton in the reverse direction, making it a conjugate acid

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8
Q

Explain conjugate base

A

[Bronsted-Lowry / Proton transfer theory]

Since a BL acid donates a proton to form an ion, the ion can accept a proton in the reverse direction, making it a conjugate base

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9
Q

Amphiprotic vs Amphoteric

A

Amphiprotic = both can donate and accept a proton

Amphoteric = both acts as acid and base

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10
Q

Example of amphoteric BL acid / base

A

H2O (water)

BL acid: H2O + HN3 –> NH4+ + OH-
BL base: H2O + HCl –> H3O+ + Cl-

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11
Q

What is a Lewis (electron pair transfer theory) acid?

A

A substance that can receive a pair of elections

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12
Q

What is a Lewis (electron pair transfer theory) base?

A

A substance that can donate a pair of elections

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13
Q

Limitation of Lewis theory

A
  1. Since there is the donation of an electron pair, dative bonding must happen. However, this is not always true. It cannot explain acid-base reactions that do not involve dative (coordinate) bonding.

(common acids & bases don’t have dative bonding)

HCl + NaOH –> NaCl + H2O

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14
Q

Are lewis bases = BL bases?

A

Yes

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15
Q

Are lewis acids = BL acids?

A

No.

BL acid is a subset of Lewis acid. Because BL acids need to have H+ present, which is not necessary in lewis acid.

Lewis acids that are deficient of electrons are not BL acids. Lewis acids that do not have hydrogen are not BL acids.

Eg: BF3 (boron trifluoride), AlCl3 (aluminium chloride)

B and Al only have 6 valence e-

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16
Q

Characteristics of acids

A
  1. Sour
  2. Corrosive
  3. Causes colour change in pH indicators
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17
Q

Characteristics of bases

A
  1. Bitter
  2. Soapy
  3. Corrosive
  4. Causes colour change in pH indicators
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18
Q

Uses of acids?

A
  1. HCl: Clean steel
  2. HNO3: Fertiliser
  3. H2SO4: Batteries, fertiliser
  4. H3PO4: Detergent, fertiliser, soft drinks
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19
Q

Uses of base?

A
  1. Al(OH)3: Colourfast fabric, water treatment, plant.
    (it is a sticky gel that traps impurities)
  2. NaOH: Drain cleaner, soap, textiles, paper, bleach
  3. NH3: Cleaners, fertilizer, make nylon
  4. KOH: Batteries, fertilizer, soap, etc
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20
Q

Define pH

A

The measure of concentration of free hydrogen ions or hydroxide ions in a solution

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21
Q

Strong VS Weak acid

A

Strong –> completely ionized in water to form hydrogen ions

Weak –> partially ionized in water to form hydroxide ions

The concentration of hydrogen ions released by strong acids is higher, hence those acids are stronger

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22
Q

What is strength of acid?

A

Degree of ionisation to produce hydrogen ions, when acid dissolves in water

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23
Q

What is basicity of acid?

A

The number of moles of hydrogen ions produced when 1 mole of acid dissolves in water

24
Q

Explain what is a monobasic acid

A

A monobasic acid has 1 replaceable hydrogen atom per one acid molecule

Can only donate 1 hydrogen ion per mole of acid for an acid-base reaction

No step-wise dissociation

25
Q

Explain what is a dibasic acid

A

A dibasic acid has 2 replaceable hydrogen atoms per one acid molecule

Can donate 2 hydrogen ions per mole of acid for an acid-base reaction

Dissociates in 2 steps

26
Q

Explain what is a tribasic acid

A

A dibasic acid has 3 replaceable hydrogen atoms per one acid molecule

Can donate 3 hydrogen ions per mole of acid for an acid-base reaction

Dissociates in 3 steps

27
Q

Examples of monobasic acid

A
  1. HCl (hydrochloric)
  2. HNO3 (nitric)
  3. CH3COOH (ethanoic)
28
Q

Examples of dibasic acid

A
  1. H2SO4 (sulfuric)
  2. H2CO3 (carbonic)
29
Q

Examples of tribasic acid

A
  1. H3PO4 (phosphoric)
30
Q

List the strong acids

A
  1. HCl
  2. HNO3
  3. H2SO4
31
Q

List the weak acids

A
  1. H3PO4
  2. H2CO3
  3. CH3COOH
32
Q

Acid + metal –>

A

Salt + H2

33
Q

Acid + base (metal oxide / hydroxide) –>

A

Salt + H2O

34
Q

Acid + metal carbonate –>

A

Salt + H2O + CO2

35
Q

Ammonium salt + Alkali (metal oxide / hydroxide)

A

Salt + Ammonia (g) + H2O

36
Q

Metal + water –>

A

Salt + H2

(v reactive metal: hydroxide, mildly reactive metal: oxide)

37
Q

Bonding & structure of acid

A

Covalent bonding, simple molecular structure

*but they become ions when dissolved in water

38
Q

Bonding & structure of base

A

Ionic bonding, giant ionic lattice structure

*except for NH3 (aq) which has both covalent & ionic bonds when dissolved in water

NH4+ and OH-

NH4+ has dative covalent bonds

39
Q

What is strength of alkali

A

Degree of ionisation to produce hydroxide ions, when alkalis dissolve in water

40
Q

What is a strong alkali

A

A substance that completely ionises in water to produce hydroxide ions

41
Q

What is a weak alkali

A

A substance that partially ionises in water to produce hydroxide ions

42
Q

List the strong alkalis

A

NaOH (sodium hydroxide, Lye)
KOH
Ca(OH)2 (limewater)

43
Q

List a weak alkali

A

NH3, Ammonia

44
Q

Basicity of alkalis

A

The number of moles of hydroxide ions produced when 1 mole of alkali dissolves in water

45
Q

What is a monobasic alkali

A

An alkali that has 1 replaceable hydroxide ion per alkali molecule

46
Q

Examples of monobasic alkali

A
  1. NaOH
  2. KOH
  3. NH3
47
Q

Examples of dibasic alkali

A
  1. Ca(OH)2
48
Q

What are acidic oxides?

A

Non-metal oxides that act as acids

49
Q

Examples of acidic oxides?

A
  1. CO2
  2. NO2
  3. SO2
  4. SO3
  5. P4O10 (phosphorus pentoxide)
50
Q

What are neutral oxides?

A

Non-metal oxides that don’t react with both acid and alkali

51
Q

Examples of neutral oxides?

A
  1. CO
  2. NO (nitric oxide)
  3. N2O (nitrous oxide)
  4. H2O
  5. H2O2
52
Q

What are basic oxides?

A

Metal oxides that act as a base

53
Q

Examples of basic oxides?

A
  1. MgO
  2. Na2O
  3. CaO
54
Q

What are amphoteric oxides?

A

Metal oxides that can act as both a base and alkali, hence react with both alkalis and bases

55
Q

Examples of amphoteric oxides?

A
  1. Al2O3
  2. PbO
  3. ZnO
56
Q

Colour change of phenolphthalein

A

under pH9: colourless
above pH9: pink

57
Q
A