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Chemistry > ATAR Unit 3 (1) > Flashcards

ATAR Unit 3 (1) Flashcards

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1
Q

open system

A

exchanges energy & matter w. surroundings

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2
Q

closed system

A

exchanges only energy w. surroundings

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3
Q

reversible reaction

A

reaction where the products once formed can react together to re-form the reactants

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4
Q

reversibility [chemical]

A

only some chemical changes are reversible

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5
Q

reversibility [physical]

A

physical changes are usually reversible

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6
Q

four common reversible systems

A

evaporation & condensation of water [physical]

saturated sugar / salt solution [physical]

oxygen transport in blood [physical]

synthesis of ammonia [chemical]

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7
Q

static equilibrium

A

position of balance is achieved but no processes are happening [e.g. seesaw]

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8
Q

dynamic equilibrium

A

equal rate of forward & reverse reactions is achieved in closed systems

macroscopic properties remain constant & microscopic processes continue

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9
Q

reversibility [considering activation energy]

A

reactants collide w. sufficient energy [Eₐ] to form products

products collide w. sufficient energy [reverse Eₐ] to form reactants

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10
Q

extent of reaction

A

indicates how much product is formed at equilibrium

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11
Q

rate of reaction

A

measures the change in reactants & products w. time

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12
Q

graphing rate vs time

A

shape of the graph [rate theory]

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13
Q

graphing concentration vs time

A

stoichiometry of the reaction [coefficient]

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14
Q

le chatalier’s principle

A

if stress is applied to a system at equilibrium, the system will act to oppose the stress & restore equilibrium

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15
Q

increase temperature [exothermic reaction]

A

endothermic reaction absorbs heat

reverse reaction is favoured

moves to left-hand-side

reactants are favoured

K𝒸 decreases

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16
Q

decrease temperature [exothermic reaction]

A

exothermic reaction releases heat

forward reaction is favoured

moves to right-hand-side

products are favoured

K𝒸 increases

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17
Q

increase temperature [endothermic reaction]

A

endothermic reaction absorbs heat

forward reaction is favoured

moves to right-hand-side

products are favoured

K𝒸 increases

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18
Q

decrease temperature [endothermic reaction]

A

exothermic reaction releases heat

reverse reaction is favoured

moves to left-hand-side

reactants are favoured

K𝒸 decreases

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19
Q

increasing temperature effect [collision theory]

A

more kinetic energy within reactants & products

molecules move faster

more successful collisions

greater rate of reaction

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20
Q

pressure’s effect on K𝒸

A

changing pressure has no effect on the K𝒸 value

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21
Q

what if the number of molecules is equal on both sides of the chemical equation [2 : 2 molecules equation] ? [pressure]

A

change in pressure will not shift the position of equilibrium [no effect]

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22
Q

volume’s effect on pressure

A

if volume is doubled, pressure is halved

if volume is halved, pressure is doubled

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23
Q

increase pressure [3 : 2 molecules equation]

A

moves to the side of fewest molecules

net forward reaction

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24
Q

decrease pressure [3 : 2 molecules equation]

A

moves to the side of more molecules

net reverse reaction

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25
increasing pressure effect [collision theory]
reduced volume equals increased pressure molecules are closer together increased frequency of collisions greater rate of reaction
26
increase reactant
formation of more products position of equilibrium shifts right net forward reaction
27
increase product
formation of more reactants position of equilibrium shifts left net reverse reaction
28
decrease reactant
formation of more reactants position of equilibrium shifts left net reverse reaction
29
decrease product
formation of more products position of equilibrium shifts right net forward reaction
30
inert gas' effect on K𝒸
adding an inert gas has no effect on the K𝒸 value
31
concentration's effect on K𝒸
changing concentration has no effect on the K𝒸 value
32
increase dilution
moves to the side of more molecules equilibrium is restored
33
catalyst's effect on K𝒸
a catalyst has no effect on the K𝒸 value
34
homogenous system
reactants & products are in the same phase
35
heterogeneous system
reactants & products are in different phases
36
K𝒸 expression
products to the power of their coefficient[s] divided by reactants to the power of their coefficient[s]
37
what species do & do not appear in a K𝒸 expression ?
solids & liquids do not appear aqueous & gases do appear liquids do appear [if all species in the reaction are liquid] liquids do appear [if H₂O is a reactant / product]
38
Q𝒸 > K𝒸
moves to left-hand-side more reactants
39
Q𝒸 < K𝒸
moves to right-hand-side more products
40
10⁻⁴ < K𝒸 < 10⁴
extent of reaction is significant reactants = products [at equilibrium]
41
K𝒸 > 10⁴
extent of reaction is complete products > reactants [at equilibrium] equilibrium lies to the right-hand-side
42
K𝒸 < 10⁻⁴
extent of reaction is negligible reactants > products [at equilibrium] equilibrium lies to the left-hand-side
43
reversed equation's effect on K𝒸
K𝒸 is inversed
44
doubled equation's effect on K𝒸
K𝒸 is squared
45
halved equation's effect on K𝒸
K𝒸 is square-rooted
46
acid [arrhenius model]
substance that produces hydrogen ions [H⁺] in an aqueous solution [e.g. HCl]
47
base [arrhenius model]
substance that produces hydroxide ions [OH⁻] in an aqueous solution [e.g. NaOH]
48
neutralization reaction [arrhenius model]
reaction where hydrogen ions react w. hydroxide ions to form water [e.g. H₂O ⇌ H⁺ + OH⁻]
49
acid + base →
salt + water [e.g. HCl + NaOH → NaCl + H₂O]
50
acid + metal →
salt + hydrogen gas [e.g. 2HCl + Mg → MgCl₂ + H₂]
51
acid + carbonate →
salt + water + carbon dioxide gas [e.g. HCl + CaCO₃ → CaCl₂ + H₂O + CO₂
52
acid [brønsted–lowry model]
proton [H⁺] donor [e.g. HSO₄⁻]
53
base [brønsted–lowry model]
proton [H⁺] acceptor [e.g. NH₃]
54
neutralization reaction [brønsted–lowry model]
reaction where an acid reacts w. a base [e.g. NH₃ + H₂O ⇌ NH₄⁺ + OH⁻]
55
conjugate acid-base pair
two species that differ by one proton [H⁺] [e.g. HNO₃ & NO₃⁻]
56
conjugate acid
when a base accepts a proton [H⁺]
57
conjugate base
when an acid donates a proton [H⁺]
58
amphiprotic substances
can act as either acids or bases; can either donate or accept protons [e.g. H₂O]
59
monoprotic acid
can donate one proton [e.g. HCl]
60
diprotic acid
can donate two protons [e.g. H₂SO₄]
61
triprotic acid
can donate three protons [e.g. H₃PO₄]
62
polyprotic acid
can donate more than one proton to a base
63
extent of dissociation [polyprotic acids]
first dissociation is greater than each subsequent dissociation; final dissociation occurs to the least extent; subsequent acids become progressively weaker
64
strong acid
dissociates completely in aqueous solution; readily donates protons [e.g. HCl, H₂SO₄, HNO₃]
65
weak acid
dissociates partially in aqueous solution; high proportion of undissociated acid particles [e.g. CH₃COOH, H₂CO₃, H₃PO₄]
66
strong base
dissociates completely in solution; readily accepts protons [e.g. NaOH]
67
weak base
dissociates partially in solution; high proportion of undissociated base particles [e.g. NH₃]
68
relative strength relationship of conjugate acid-base pairs
stronger the acid, weaker the conjugate base [if an acid readily donates a proton, its conjugate base does not readily accept it back] stronger the base, weaker the conjugate acid [if a base readily accepts a proton, its conjugate acid does not readily donate it forward]
69
strength vs concentration
strength [strong / weak] refers to the degree of dissociation [tendency to donate / accept protons] of an acid / base concentration [concentrated / dilute] refers to the relative amount of solute in a given volume of solution
70
water
very weak electrolyte & undergoes self-ionization to a very small extent
71
K𝒸 define
equilibrium constant / point of balance that exists in a reaction
72
Kᴡ define
ionic product / ionization constant of water
73
Kᴡ expression
[H₃O⁺][OH⁻] = 1 x 10⁻¹⁴
74
temperature's effect on Kᴡ
increase temperature, increase Kᴡ decrease temperature, decrease Kᴡ
75
pH expression
-log[H₃O⁺]
76
dilution's effect on pH [strong acids & bases]
no effect on the number of moles [c₁V₁ = c₂V₂]
77
dilution's effect on pH [acid at 25ºC]
pH increases until close to 7
78
dilution's effect on pH [base at 25ºC]
pH decreases until close to 7
79
buffer
solution that is conjugate in nature & resists changes in pH when small amounts of acid / bases are added
80
general equation [buffer]
HA ⇌ H⁺ + A⁻ BOH ⇌ B⁺ + OH⁻
81
buffer composition
weak acid & conjugate base weak base & conjugate acid
82
increase H⁺ to buffer [small amount]
H⁺ reacts w. A⁻ moves to left-hand-side [le chatalier's principle] more HA [H⁺] remains relatively constant pH does not change significantly
83
increase H⁺ to buffer [large amount]
H⁺ reacts w. A⁻ moves to left-hand-side [le chatalier's principle] more HA exhaustion of A⁻ [H⁺] soars pH plummets
84
increase OH⁻ to buffer [small amount]
OH⁻ reacts w. H⁺ [neutralization] moves to right-hand-side [le chatalier's principle] more weak acid HA dissociates [H⁺] remains relatively constant pH does not change significantly
85
increase OH⁻ to buffer [large amount]
OH⁻ reacts w. H⁺ [neutralization] moves to right-hand-side [le chatalier's principle] more weak acid HA dissociates exhaustion of HA [H⁺] plummets pH soars
86
two solutions [buffer]
CH₃COOH + H₂O ⇌ CH₃COO⁻ + H₃O⁺ NH₃ + H₂O ⇌ NH₄⁺ + OH⁻ [inverse response]
87
Kₐ define
acid dissociation constant
88
larger Kₐ
greater extent of dissociation more products more [H⁺] stronger the acid
89
smaller Kₐ
lesser extent of dissociation more reactants less [H⁺] weaker the acid
90
Kₐ of polyprotic acids
first dissociation has a greater Kₐ than each subsequent dissociation; each following step, Kₐ decreases; it becomes increasingly harder to lose a proton as the acid species becomes increasingly negative
91
acid-base indicator
weak acid / weak base where the conjugate acid form is one colour & the conjugate base form is another colour
92
pH range [indicator]
related to the indicator's dissociation constant position of equilibrium changes depending on the solution's pH colour change occurs when pKₐ = pH
93
equivalence point [neutralization reaction]
when the amount [number of moles] of acid & base are in stoichiometric ratio [equal]
94
end point
when the indicator changes colour corresponds closely w. the equivalence point
95
transition point [indicator]
when concentration of the acid form & base form are equal pH = pKₐ = -log[H⁺]
96
equivalence point
when the amount [number of moles] between reactants are in stoichiometric ratio [equal]
97
half equivalence point
when the amount [number of moles] between conjugate acid-base pair are in stoichiometric ratio [equal] pH = pKₐ = -log[H⁺]
98
useful relationships [pKᴡ]
pKᴡ = pH + pOH = 14 pKᴡ = pKₐ + pKᵦ = 14
99
useful relationships [Kᴡ]
Kᴡ = [H₃O⁺][OH⁻] = 1 x 10⁻¹⁴ Kᴡ = Kₐ x Kᵦ = 1 x 10⁻¹⁴

Chemistry (4 decks)

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