Equilibrium Flashcards

1
Q

chemical equilibrium

A

state where the forward reaction rate(rf) is equal to the reverse reaction rate(rr)

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2
Q

dynamic equilibria

A

there is constant movement and each species is actively consumed and actively formed

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3
Q

criteria for a system to be in equilibrium

A
  1. constant macroscopic properties
  2. closed system
  3. shift in response to changes
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4
Q

macroscopic property

A

property observed with the naked eye

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5
Q

criteria: macroscopic properties

A

should have constant concentrations, pH, color, and temperature

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6
Q

closed system

A

a system where chemicals do not enter or leave

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7
Q

steady state

A

system that appears to be at equilibrium but chemicals are entering and leaving the system at the same time

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8
Q

criteria: shift in response

A

a change(stress) causes the system to respond

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9
Q

equilibrium stages: 1

A

reactant concentrations are high, rf is at the highest

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10
Q

equilibrium stages: 2

A

[A] and [B] and rf decreases
[C] and [D] and rr increases

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11
Q

equilibrium stages: 3

A

[A] [B] [C] [D] are constant and rr and rf are equal

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12
Q

Le Chatlier’s principle

A

an equilibrium when subjected to stress will shift to alleviate the stress

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13
Q

stress

A

any change that favors rf or rr

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14
Q

stress: change in concentration

A

if the concentration of a chemical species increases, then the system will shift to consume that species; if the concentration decreases, the system will shift to produce that species

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15
Q

shift right

A

when a system shifts to favor the products

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16
Q

shift left

A

when a system shifts to favor the reactants

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17
Q

adding a catalyst

A

does not affect equilibrium, but systems will alleviate the stresses applied faster

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18
Q

equilibrium position

A

relative concentrations of chemical species in equilibrium expressed in percent yield

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19
Q

shift right

A

if the percent yield is above 50%

20
Q

shift left

A

if the percent yield is less than 50%

21
Q

partial pressure

A

pressure exerted by an individual gas in a mixture

22
Q

partial pressure is to gaseous equilibria as

A

osmotic pressure is to solution equilibria

23
Q

gas pressure is directly proportional to gas concentration and

A

osmotic pressure is directly proportional to solution concentration

24
Q

stress: change in volume

A

the side of equilibrium with the greater sum of coefficients will be more sensitive to volume change

25
Q

stress: change in temperature

A

a system in equilibrium will shift to replace lost kinetic energy or shift to remove added kinetic energy

26
Q

a system in equilibria will shift

A

before the stress is fully applied

27
Q

when heat is added

A

the endothermic direction is favored

28
Q

Haber Bosch Reaction

A

N2 +3H2 -> 2NH3 +92.4 kJ

29
Q

haber reactor pressure

A

increased to 3.5 x 10^4 kPa

30
Q

equilibrium expression

A

formula for finding the equilibrium constant in terms of concentrations of products and reactants

31
Q

equilibrium constant(keq)

A

numerical value that related the concentrations of products to the concentration of reactants in equilibria

32
Q

keq requirements

A

-units vary and are not required to be expressed
-temperature dependent

33
Q

products are favored, shift right

A

keq > 1

34
Q

reactants are favored, shift left

A

keq < 1

35
Q

equilibrium law

A

the expression of a balanced chemical equation and an equilibrium expression together

36
Q

reaction quotient(Q or trial keq)

A

numerical value calculated from taking any set of concentrations and plugging them into an equilibrium expression

37
Q

shift left

A

Q>Keq

38
Q

shift right

A

Q<Keq

39
Q

exception to le chatelier

A

if only one chemical species is present in an equilibrium expression, the system will shift to completely alleviate a stress that affects its concentration

40
Q

ICE Box

A

table that is used to solve calculations in systems of equilibria where ICE is an acronym
-concentrations needs to be in molarity
-pay attention to the coefficients

41
Q

mass action expression

A

equilibrium expressions in terms of concentration or partial pressure

42
Q

14.7 psi

A

psi in atm

43
Q

760 mmHg

A

mmHg in atm

44
Q

Kp=

A

Kc(RT)^(delta n)

45
Q

delta n=

A

(c+d)-(a+b)

46
Q

ideal gas law constant(R)

A

0.08206 (L x atm)/(mol x K)