Chemical Equilibrium

Question 1

when two opposing reactions occur simultaneously at the same rate, what is achieved?

Answer 1

chemical equilibrium

Question 2

this occurs when the rate of forward rxn is equal to the rate of reverse rxn

Answer 2

equilibrium

Question 3

formula for chemical equilibrium assuming A→B

Answer 3

Keq = Kf/Kr
or
[B]/[A]

Forward rate constant over Reverse rate constant/products over reactants

Keq is often associated with Kc or K; When Kp, it is used for partial pressure (or pressure only) and rxn must be homogenous w/o pure solids

Question 4

If 1N_2(g) + 3H_2(g) ⇄ 2NH_3(g) is given, what is Kc and Kp?

Answer 4

Kc = [NH₃]²/[N₂] [H₂]³

Kp = P[NH₃]²/P[N₂] P[H₂]³

Question 5

If 1N_2(g) + 3H_2(g) ⇄ 2NH_3(g) is given, what is Kp if Kc is 9.60 at 300^oC

Answer 5

use formula Kp = Kc (RT)^Δn
wherein: R = gas constant 0.0821 Latm/molK
T = absolute temp (+273.15)
Δn = product - reactant coefficients
Therefore
Kp = 9.60 ((0.0821)(300+273.15))^2-4
Kp = 4.34 x 10^-3

hehe i added para lng makita use ng formula

Question 6

If 1N_2(g) + 3H_2(g) ⇄ 2NH_3(g) is given, what is Kc if Kp is 1.45 x 10^-3 at 500^oC

Answer 6

use formula Kp = Kc (RT)^Δn
wherein: R = gas constant 0.0821 Latm/molK
T = absolute temp (+273.15)
Δn = product - reactant coefficients
Therefore
Kc = Kp/(RT)^Δn
Kc = 1.45 x 10^-3/((0.0821)(500+273.15))^2-4
Kc = 5.84

hehe i added para lng makita use ng formula

Question 7

If K > 1, which side is preferred in a reaction?

Answer 7

products dominate and is favored. equi is to the right

if K and 1, look at tail. If Q and K, tingin sa bunganga

Question 8

If K < 1, which side is favored?

Answer 8

reactant side is favored; equilibrium is to the left

if K and 1, look at tail nito (<). If Q and K, tingin sa bunganga (<)

Question 9

what do you call the equilibrium wherein reactants and products are in different phases?

Answer 9

heterogenous equilibrium

Question 10

what do u call the equilibrium wherein products and reactants are in the same phases?

Answer 10

homogenous equilibrium

Question 11

what do u call this equilibrium that has many steps?

Answer 11

multiple equilibrium

when looking for K, multiply equi constants for each step

Question 12

If K = equilibrium constant, what is Q for?

Answer 12

Q = initial concentration of products over reactants

same as K pero this one deals w/ the initialzzxzc

Question 13

what can u say if Q = K

prod-favored, reactant-favored, or at equi

Answer 13

system is at equilibrium

Question 14

what is favored when Q < K?

Answer 14

forward rxn is favored; product-favored

if K and 1, look at tail. If Q and K, tingin sa bunganga

Question 15

what is favored when Q > K?

Answer 15

reverse rxn is favored; reactant-favored

if K and 1, look at tail. If Q and K, tingin sa bunganga

Question 16

what do u call the principle wherein it states that if stress is applied to a system in equilibrium, the system will adjust in such a way that the stress is partially offset to achieve a new equilibrium?

basically, the system will try to achieve equilibrium if may imbalance

Answer 16

Le Chatelier’s principle

Question 17

determine if forward rxn or reverse rxn is favored

↑ in conc of products

Answer 17

reverse rxn

Question 18

determine if forward rxn or reverse rxn is favored

↑ in conc of reactants

Answer 18

forward rxn

Question 19

determine if forward rxn or reverse rxn is favored

↓ conc of reactants

Answer 19

reverse rxn

Question 20

determine if forward rxn or reverse rxn is favored

↓ conc of products

Answer 20

forward rxn

Question 21

what does it mean if a rxn has a positive enthalpy?

Answer 21

it means it is endothermic in nature

it increases in temp as rxn goes on (assuming forward onli)

Question 22

what does it mean when a rxn has a negative enthalpy?

Answer 22

it means it is exothermic

decreases temp as rxn goes on (assuming forward rxn)

Question 23

determine if forward rxn or reverse rxn is favored

in an endothermic rxn, what happens if u increase temp?

Answer 23

forward rxn is favored

tip: look wer the endothermic side is, usually ↑ in temp is on dat side

similarly, the decrease in temperature is found sa exothermic side ng rxn (product or reactant)

Question 24

determine if forward rxn or reverse rxn is favored

↓ temp in endothermic rxn

Answer 24

reverse rxn is favored

Question 25

determine if forward rxn or reverse rxn is favored ↑↓

↑ temp in exothermic

Answer 25

reverse side is favored

Question 26

determine if forward rxn or reverse rxn is favored ↑↓

↓ temp in exothermic

Answer 26

forward rxn is favored

Question 27

determine if forward rxn or reverse rxn is favored ↑↓

↑P (only applicable to gases)

Answer 27

favors side w/ fewer gas molecules

↑P ↓V

Question 28

determine if forward rxn or reverse rxn is favored ↑↓

↓P in gases

Answer 28

favors side w/ more gas molecules

↓P ↑V

Question 29

A catalyst affects the equilibrium and speeds up reactions, allowing system to reach equilibrium.

True or False?

Answer 29

False. A catalyst does not affect equi, but indeed it speeds up rxns (so it affects rxn rates but not equi)