Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Chem 2 Heider > Ch 14 - Chemical Equilibrium > Flashcards

Ch 14 - Chemical Equilibrium Flashcards

(67 cards)

Start Studying
1
Q

Equilibrium Constant

A

how far a chemical reaction goes based on an experimentally measurable quantity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does a large equilibrium constant mean?

A

Nearly all reactants proceed to products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

A reaction with can

A

reach an equilibrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

K

A

an equilibrium constant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Larger K value =

A

more reaction proceeds towards the products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Hb + O2 HbO2

A
  • hemoglobin attached to blood and oxygen are an equilibrium process
    - in the lungs O2 is high so reaction shifts right creating more HbO2 blood
    - stores it with blood and move it to muscles
    - in the muscles the oxygen is low and the Hb releases O2 to restore equilibrium
    - hemoglobin binds oxygen when the surrounding concentration is high, but releases oxygen when the surrounding oxygen concentration is low
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How does a fetus get O2 in the womb?

A

maternal and fetal circulation never mix but the fetal K is different allowing oxygen to be “handed off” from the mother circulation at very close proximity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Reversible

A

a reaction that can proceed in both the forward and reverse direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Dynamic equilibrium

A

for a chemical reaction this is the condition in which the rate of the forward reaction equals the rate of the reverse reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why in dynamic equilibrium products and reactants continue to

A

occur simultaneously but at the same rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is not true with dynamic equilibrium?

A

the products and reactants ARE NOT the same amount necessarily

Same rate NOT amount

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

As the amount of reactants goes down the amount of products goes up leading to

A

a slower rate of reactants(assuming non zero order rxn)

  • the pool of reactants gets smaller
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

the rate of a reaction is direction proportional to the pool of reactants so as the pool decreases the rate goes down and likewise as…..

A

the amount of products increases the rate increases

  • eventually the slow down of the rate of reactants and the speed up of the rate of products reaches an equilibrium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the equilibrium constant used for?

A

a way to quantify the concentrations of the reactants and products at equilibrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Equilibrium Constant(K)

A

the ratio at equilibrium of the concentrations of the products raised to their stoichiometric coefficients divided by the concentrations of the reactants raised to their stoichiometric coefficients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Law of mass action

A
  • K = ([C]^c[D]^d)/([A]^a[B]^b)

- products/reactants raised to their coefficients

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

K &laquo_space;1(equilibrium to the left)

A
  • reverse reaction is favored
    - forward reaction does not proceed very far
    - more reactants than products
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

K = 1(equilibrium in the middle)

A
  • neither direction is favored

- forward reaction proceeds about halfway

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

K&raquo_space; 1 (equilibrium to the right)

A
  • forward reaction is favored
    - forward reaction proceeds essentially to completion
    - more products than reactants
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

reverse the equation, invert the equilibrium constant

A
  • A + 2B 3C
    - Kforward = [C]^3/([A][B]^2)
    - 3C A + 2B
    - Kreverse = ([A][B]^2)/[C]^3
    - Kreverse = 1/Kforward
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

if you multiply the coefficients in the equation by a factor, raise the equilibrium constant to the same factor

A
  • A + 2B 3C
    - K = [C]^3/([A][B]^2)
    - nA + 2n B 3n C
    - K’ = [C]^3n/([A]^n[B]^2n)
    = ([C]^3/([A][B]^2))^n
    = K^n
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

If you add two or more individual chemical equation to obtain an overall equation, multiply the corresponding equilibrium constants by each other to obtain the overall equilibrium constant

A
  • A2B
    - K1 = [B]^2/[A]
    - 2B 3C
    - K2 = [C]^3/[B]^2
    - sum: A3C
    - Koverall = [C]^3/[A]
    - Koverall = (K1)(K2)
    - ([B]^2/[A])([C]^3/[B]^2)
    = [C]^3/[A]
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

For gaseous reactions the partial pressure of a particular gas is….

A

proportional to its concentration.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Can the equilibrium constant be expressed in terms of the partial pressures of the reactants and products?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Kc = ([SO2]^2[O2]/[SO3]^2) find Kp
Kp = ((Pso2)^2(Po2))/(Pso3^2)
26
Kp =
the equilibrium constant with respect to partial pressures
27
What is the difference with Kp compared to Kc?
Kp takes the form of the expression for Kc except it uses partial pressure for each gas in place of concentration
28
Kp = Kc(RT)^delta(n)
- R = .08206 (L*atm/mol*K) - T = temp kelvin - delta n = change in moles of the reaction - Product stoichiometric coefficient – reactant stoichiometric coefficient - Kp = equilibrium constant with respect to partial pressure - Kc = equilibrium constant with respect to concentration
29
as long as concentration units are expressed in molarity for Kc and atm for Kp you do not need to
write their corresponding units | - 1.5 M or 1.5 atm becomes 1.5
30
solids are not included in the equilibrium expression because their constant value is incorporated into the value of K
- the concentration of a solid DOES NOT change - 2Co(g) CO2(g) + c(s) - Kc = [CO2]/[CO]^2 - similarly pure liquids are omitted from the expression
31
the most direct way to obtain an experimental value for the equilibrium constant of a reaction is to measure the
concentrations of the reactants and products in a reaction mixture at equilibrium
32
H2(g) + I2(g) 2HI(g)
- Kc = [HI]^2/([H2][I2]) - Kc = .78^2/(.11)(.11) = 5.0 * 10^1 - always in M though not written(unitless)
33
ICE Table A(g) 2B(g)
[A] [B] - Initial 1.00 0.00 - Change -0.25 +0.50 - Equilibrium 0.75 0.50 K = [B]^2/[A] = .5^2/.75 = .33
34
reaction quotient(Qc)
the ratio – at any point in the reaction – of the concentrations of the products raised to their stoichiometric coefficients divided by the concentrations of reactants raised to their stoichiometric coefficients
35
When K and when Q?
- K at equilibrium | - Q not at equilibrium
36
the value of Q relative to K is a measure of the progress of the reaction toward equilibrium
- at equilibrium Q = K
37
Q < K
reaction goes to the right(towards products)
38
Q > K
reaction goes to the left(towards reactants)
39
Q = K
reaction is at equilibrium
40
ICE table with x A(g) 2B(g) and K = 0.33
[A] [B] Initial 1.0 0.0 Change -x +2x Equil 1.0 – x 2x - K = [B]^2/[A] = 2x^2/(1.0-x) = .33 = 4x^2/(1.0-x) = 0.33
41
Le Chatelier’s Principle
when a chemical system at equilibrium is disturbed, the system shifts in a direction that minimizes the disturbance - a system at equilibrium tends to maintain equilibrium and bounces back when disturbed
42
What does a system do with disturbances?
when a system is disturbed the system reacts to counter the disturbance
43
3 main types of system disturbances
- change in concentration of a product or reactant - change in volume or pressure - change in temperature
44
Change in concentration of product or reactant: N2O4(g) 2NO2(g) Add NO2
if NO2 is added the reaction will shift left(proceeds in the reverse direction) consuming some No2 and creating more N2O4 to bring the NO2 concentration down until a new equilibrium is reached - Before adding NO2: Q = K - Immediately after addition of NO2: Q > K - Reaction shifts left to reestablish equilibrium
45
Change in concentration of product or reactant: N2O4(g) 2NO2(g) Add N2O4
if N2O4 is added the reaction will shift right to reestablish equilibrium - before adding N2O4: Q = K - Immediately after addition of N2O4: Q < K - Reaction shifts to right to reestablish equilibrium
46
Change in concentration of product or reactant: increasing the concentration of one or more of the reactants(makes Q
the reaction to shift to the right(in the direction of the products)
47
Change in concentration of product or reactant: increasing the concentration of one of more of the products(makes Q>K) causes
the reaction to shift to the left(in the direction of the reactants)
48
Change in concentration of product or reactant: decreasing the concentration of one or more of the reactants(makes Q > K) causes
the reaction to shift to the left(in the direction of the reactants)
49
Change in concentration of product or reactant: decreasing the concentration of one or more of the products(makes Q
the reaction to shift to the right(direction of the products)
50
The effect of a volume(or pressure) change on equilibrium
- a decrease in volume causes an increase in pressure | - an increase in volume causes a decrease in pressure
51
The effect of a volume(or pressure) change on equilibrium: N2(g) + 3H2(g) 2NH3(g)
PV=nRT where lower mols of gas(n) = lower pressure(P) - 4 mols on left and 2 mols on right - higher pressure will shift the system to the right to minimize the equilibrium disturbance - If the volume is increased then the equilibrium will more left converting 2mols back to 4 mols - what happens if an inert gas is added to increase the pressure? - NOTHING! The overall pressure increased but the partial pressures of the reactants and products did not change so equilibrium is not disturbed
52
The effect of a volume(or pressure) change on equilibrium: decreasing the volume causes
the reaction to shift in the direction that has the fewer moles of gas particles
53
The effect of a volume(or pressure) change on equilibrium: increasing the volume causes
the reaction to shift in the direction that has the greater number of moles of gas particles
54
The effect of a volume(or pressure) change on equilibrium: if a reaction has an equal number of moles of gas on both sides of the chemical equation then
a change in volume produces no effect on the equilibrium
55
The effect of a volume(or pressure) change on equilibrium: adding an inert gas to the mixture at a fixed volume has
no effect on the equilibrium
56
Exothermic Reaction
A + B C + D + heat
57
Endothermic Reaction
A + B + heat C + D
58
The Effect of a Temperature Change on Equilibrium: at constant pressure(exothermic reaction) raising the temperature
of an exothermic reaction(adding heat) is similar to adding more product, causing the reaction to shift left(absorbing heat and producing more reactants) - unlike adding more product the change in temperature will change the value of the equilibrium constant(add heat = smaller K)
59
The Effect of a Temperature Change on Equilibrium: (exothermic reaction)at constant pressure, lowering the temperature causes
the reaction to shift to the right, releasing heat and producing more products
60
The Effect of a Temperature Change on Equilibrium: | endothermic reaction)at a constant pressure, raising the temperature(adding heat
causes the reaction to shift right to absorb the added heat
61
The Effect of a Temperature Change on Equilibrium: | endothermic reaction) at a constant pressure, lowing the temperature(removing heat
causes the reaction to shift left, form less products, and lowering the value of K
62
The Effect of a Temperature Change on Equilibrium: in an exothermic chemical reaction
heat is a product A + B C + D + heat
63
The Effect of a Temperature Change on Equilibrium: In an endothermic chemical reaction
heat is a reactant A + B + heat C + D
64
The Effect of a Temperature Change on Equilibrium: increasing the temperature causes an exothermic reaction to
shift left(towards reactants); the value of the equilibrium constant decreases
65
The Effect of a Temperature Change on Equilibrium: decreasing the temperature causes an exothermic reaction to
shift right(towards products); the value of the equilibrium constant increases
66
The Effect of a Temperature Change on Equilibrium: increasing the temperature causes an endothermic reaction to
shift right(towards products); the equilibrium constant increases
67
The Effect of a Temperature Change on Equilibrium: decreasing the temperature causes an endothermic reaction to
shift left(towards reactants); the equilibrium constant decreases

Chem 2 Heider (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions