Module Six - Acid/Base Reactions Flashcards

Properties of Acids and Bases Using Brønsted–Lowry Theory Quantitative Analysis

1
Q

what is an oxyanion?

A

inorganic acid that has an oxygen attached to an element (S, N, P, C)

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2
Q

what is the name of HNO3?

A

nitric acid

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3
Q

what is the name of HCl?

A

hydrochloric acid

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4
Q

what is the name of HNO2?

A

nitrous acid

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5
Q

what is the name of HCN?

A

hydrocyanic acid

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6
Q

what is a binary acid?

A

acid that has a monoatomic ion attached

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7
Q

how are binary acids named?

A
  1. prefix - ‘hydro-‘
  2. identify the anion
  3. replace ‘-ide’ with ‘-ic’
    e. g. cyanide –> cyanic
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8
Q

what is a monoatomic ion?

A

has a charge of +1/-1

e.g. Cl-

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9
Q

what is a polyatomic ion?

A

has a charge greater than 1

e.g. SO4(2-)

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10
Q

how is an inorganic acid with a polyatomic ion named?

A
  1. replace polyatomic ion suffix
    i.e. ‘-ite’ –> ‘-ous’
    i.e. ‘-ate’ –> ‘-ic’
  2. add ‘acid
    e.g. nitrite –> nitrous
    nitrate –> nitric
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11
Q

what are the common properties of inorganic acids?

A
  • sour taste
  • conducts electricity
  • turns blue litmus to RED
  • react with and dissolve active metals with the release of a gas
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12
Q

what are the common properties of inorganic bases?

A
  • soapy feel (aqueous)
  • bitter taste
  • conducts electricity
  • turns red litmus BLUE
  • do not react with carbonates
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13
Q

define acid.

A

substance that produced hydrogen ions (H+) in solution

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14
Q

what does the H+ ion do when released from an acid in solution?

A

attaches to a water molecule to form hydronium ions (H3O+)

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15
Q

define base.

A

e that either contains oxide (O2-) or hydroxide ion (OH-)

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16
Q

what is an acid-base reaction called?

A

neutralisation reaction

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17
Q

what is the general formula for an acid-base reaction?

A

acid + base –> salt + water

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18
Q

what is an example of a base containing the oxide ion?

A

MgO

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19
Q

what is an example of a base containing the hydroxide ion?

A

NaOH

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20
Q

what is the reaction between HCl and NH3?

A

HCl(aq) + NH3(aq) –> NH4Cl(aq)

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21
Q

why is ammonia considered a base?

A

NH3(g) + H2O(l) –> NH4-(aq) +OH-(aq)

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22
Q

why is the ammonium ion considered an acid?

A

will react with a base to form salt and water

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23
Q

what is the general formula for an acid-carbonate reaction?

A

acid + carbonate –> salt + carbon dioxide + water

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24
Q

what is the general formula for an acid-metal reaction?

A

acid + metal –> hydrogen gas + salt

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25
Q

what is an example of an acid-metal reaction?

A

2HCl(aq) + Mg(s) –> MgCl2(aq) +H2(g)

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26
Q

what is an example of an acid-carbonate reaction?

A

2HCl(aq) + CaCO3(s) –> CaCl2(aq) + H2O(l) + CO2(g)

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27
Q

what is the general formula for an acid-hydrogen carbonate reaction?

A

acid _ hydrogen carbonate –> salt + water + carbon dioxide

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28
Q

what is an example of an acid-hydrogen carbonate reaction?

A

HCl(aq) + NaHCO3(s) –> NaCl +H2O(l) +CO2(g)

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29
Q

what is the hydrogen carbonate ion?

A

HCO3-

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30
Q

what is the difference between a carbonate ion and a hydrogen carbonate ion?

A

carbonate : HCO3

hydrogen carbonate: CO3(2-)

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31
Q

what is enthalpy?

A

measure of the total energy possessed by a substance

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32
Q

is energy required to break bonds or form bonds?

A

break bond

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33
Q

is energy released when breaking bonds or forming bonds?

A

formation of bonds babey

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34
Q

is the enthalpy change of an exothermic reaction positive or negative?

A

negative!!

∆H= -ve

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35
Q

is the enthalpy change of an endothermic reaction positive or negative?

A

positive

∆H= +ve

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36
Q

how can ∆H be calculated using the enthalpy of species in a reaction?

A

∆H = ∑(enthalpy of products) - ∑(enthalpy of reactants)

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37
Q

is the enthalpy of the reactants greater or lower than the products in an exothermic reaction?

A

greater (energy is lost in reaction)

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38
Q

is the enthalpy of the reactants greater or lower than the products in an endothermic reaction?

A

lower (energy is absorbed)

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39
Q

what is the standard enthalpy of neutralisation?

A

∆H when an aqueous acid and base react to form 1 mole of water

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40
Q

what is the specific heat capacity of water?

A

4.18J/K/g

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41
Q

what is the specific heat capacity unit?

A

J/K/g

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42
Q

what is specific heat capacity?

A

joules of energy required to rise the temperature of the substance by 1˚C

43
Q

how is the quantity of heat (q) calculated?

A

q = mC∆T

44
Q

how is change in enthalpy (∆H) calculated from quantity of heat (q)?

A

∆H = (-q)/n

q must be in KJ

45
Q

is the reaction between NaOH and HCl endothermic or exothermic?

A

exothermic

46
Q

can neutralisation be both endothermic and exothermic?

A

no

47
Q

is neutralisation endothermic or exothermic?

A

always exothermic

48
Q

what an application of neutralisation in everyday life?

A
  • antacid to assist with heartburn/indigestion

- toothpaste

49
Q

how does heartburn occur?

A
  • too much HCl in the stomach

- begins to travel up oesophagus and burn the tissues

50
Q

how do antacids help with heartburn?

A

neutralises the stomach acids

51
Q

how do antacids relate to neutralisation?

A
  • contains a base [e.g. Mg(OH)2]

- neutralises extra acid

52
Q

is toothpaste acidic or alkaline?

A

alkaline

53
Q

why is toothpaste alkaline?

A

neutralises acids in food we eat to prevent teeth enamel from breaking down

54
Q

how can neutralisation be used in industry?

A
  • neutralisation of soil

- neutralisation of waste waters

55
Q

why is neutralisation of soil important?

A
  • plants ability to grow is affected

- some plants can survive in acidic/basic environments though

56
Q

why is neutralisation of waste waters important?

A

if acidic/alkaline waters enter creeks and rivers, habitats and aquatic life will be hurt

57
Q

who are the five acid and base theorists?

A
  • Lavoisier
  • Davy
  • Arrhenius
  • Brønsted–Lowry
  • Lewis
58
Q

what did Antoine Lavoisier (1776) discover ?

A
  • the oxygen theory

- he demonstrated that non-metal oxides react (dissolved) with water to form acidic solutions

59
Q

what was Laviosier’s conclusion from his discovery?

A

concluded that an acid must contain oxygen

60
Q

what is a limitation of Lavoisier’s theory?

A

not all acids contain oxygen!!
e.g. HCl
He could also not explain why metal oxides were not acidic

61
Q

what did Humphry Davy (1810) discover?

A
  • the hydrogen theory
  • he observed that when HCl gas and H2S gas dissolved in water they produced acidic solutions. These molecules had no
  • recognised that the key element in acids was hydrogen
  • metals with oxygens were bases
  • acid + base –> salt + water
62
Q

what was Davy’s theory?

A

acids are substances which contain replaceable hydrogens which could be displaced by metals in solution

63
Q

what are the limitations to Davy’s theory?

A
  • not all substances that contain hydrogen are acids
  • some acid-base reactions don’t produce salt and water
  • no distinction between weak and strong acids
64
Q

what is Arrhenius’ definition of an acid?

A

substances that dissociate and ionise in water (produce H+)

65
Q

what is Arrhenius’ definition of a base?

A

substances that dissociate in water to produce hydroxide ions (OH-)

66
Q

what are the limitations to Arrhenius’ theory?

A
  • could not explain why ammonia (NH3) was a base

- does not apply to non-aqueous solvents

67
Q

what is an example of Arrhenius’ acid-base model?

A

HCl dissociates in water to produce H+ and Cl- ions

68
Q

what is Brønsted–Lowry’s definition of an acid?

A

acids are proton donors

69
Q

what is Brønsted–Lowry’s definition of a base?

A

bases are proton acceptors

70
Q

what limitation of Arrhenius did Brønsted–Lowry’s theory work out?

A

able to explain why NH3 was a base

71
Q

what is an example of a Brønsted–Lowry acid?

A

HCl(aq) + H2O(l) → H3O+(aq) + Cl-(aq)

- HCl accepts a proton!

72
Q

what is an example of a Brønsted–Lowry base?

A

NH3(aq) + H2O(l) → NH4+(aq) + OH-(aq)

- NH3 accepts a proton!

73
Q

how is a conjugate base formed?

A

when an acid loses a proton

74
Q

how is a conjugate acid formed?

A

when a base gains a proton

75
Q

how many protons do conjugate acid-base pairs differ from?

A

1

76
Q

will a strong acid produce a strong or weak conjugate base?

A

weak

77
Q

will a weak acid produce a strong or weak conjugate base?

A

strong

78
Q

will a strong base produce a strong or weak conjugate acid?

A

weak

79
Q

will a strong acid produce a strong or weak conjugate base?

A

strong

80
Q

what is the conjugate base of HCl?

A

Cl-

81
Q

what is the conjugate acid of NH3?

A

NH4+

82
Q

what are the limitations of Brønsted–Lowry’s theory?

A
  • solvent must be present (allows transfer of protons)
  • unable to explain reactions between acidic oxides and basic oxides w/o a solvent
  • unable to explain reaction between non-protonic (no H+) solvents
83
Q

what are examples of acidic oxides?

A

CO2, SO2, SO3

84
Q

what are examples of basic oxides?

A

CaO, BaO, MgO

85
Q

what is an example of non-protonic solvents?

A

AlCl3

86
Q

what is Lewis’ definition of an acid?

A

an acid is an electron pair acceptor

87
Q

what is Lewis’ definition of a base?

A

a base is an electron pair donator

88
Q

what are the limitations of Lewis’ theory?

A
  • all acid-base reactions do not involve coordinate bond formation (e.g. HCl, H2SO4)
  • does not explain strength of acids and bases
89
Q

what is the pH scale used for?

A

to quantitatively measure the acidity of a solution

90
Q

what does pH stand for?

A

hydrogen power

91
Q

how is the pH value calculated from the [H+]?

A

pH = -log[H+]

92
Q

how is [H+] calculated from the pH value?

A

10^-n

n is the pH value

93
Q

how is concentration different from strength in acids and bases?

A

concentration : amount of solute in a solution (concentrated - diluted)
strength : degree of ionisation (strong - weak)

94
Q

what makes an acid/base strong?

A

ability to ionise completely

95
Q

what makes an acid/base concentrated?

A

less solute in solution

96
Q

what are examples of a strong acid?

A

HCl, H2SO4

97
Q

what are examples of a weak acid?

A

CH3COOH. H2CO3

98
Q

what are examples of a strong base?

A

NaOH, KOH

99
Q

what are examples of a weak base?

A

NH3, CH3NH2

100
Q

what is a polyprotic acid?

A

acids that can give up more than one proton!

101
Q

What is the pH range of methyl orange?

A

pH range between 3.2 (red) and 4.4 (yellow)

102
Q

What is the pH range of bromothymol blue?

A

pH range from 6.0 (yellow) to 7.6 (blue)

103
Q

What is the pH range of phenolphthalein?

A

8.2 (colourless) to 10 (pink)

104
Q

How is the acidity of soil measured?

A

White barium sulfate is added to a wet soil sample in a petri dish. When the universal indicator is added to the white later the colour change reveals the pH of the soil water.