equilibrium

Question 1

open system

Answer 1

exchanges energy & matter with surroundings

Question 2

closed system

Answer 2

exchanges only energy with surroundings

Question 3

reversible reaction

Answer 3

products once formed can react & re-form reactants

“⇌”

products can collide with enough energy [reverse activation energy] to cause the reverse reaction

Question 4

dynamic equilibrium

Answer 4

both reactants & products are present

rate of forward reaction = rate of reverse reaction

bonds constantly broken & formed

can only occur in a closed system

Question 5

le chatelier’s principle

Answer 5

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

Question 6

temperature’s effect on equilibrium

Answer 6

permanent effect on position of equilibrium & equilibrium constant

Question 7

exothermic reaction

Answer 7

reaction that releases energy

negative enthalpy change

energy among products

Question 8

endothermic reaction

Answer 8

reaction that absorbs energy

positive enthalpy change

energy among reactants

Question 9

temperature’s collision theory

Answer 9

↑temperature = ↑kinetic energy (reactants & products)

reactants & products move faster

↑frequency of collisions; thus, successful collisions

↑rate of reaction

Question 10

decrease temperature [endothermic reaction]

Answer 10

system opposes the stress by favoring the reverse reaction

exothermic reaction releases heat

reaction moves to the left-hand-side

reactants are favored

equilibrium constant decreases

Question 11

increase temperature [endothermic reaction]

Answer 11

system opposes the stress by favoring the forward reaction

endothermic reaction absorbs heat

reaction moves to the right-hand-side

products are favored

equilibrium constant increases

Question 12

decrease temperature [exothermic reaction]

Answer 12

system opposes the stress by favoring the forward reaction

exothermic reaction releases heat

reaction moves to the right-hand-side

products are favored

equilibrium constant increases

Question 13

increase temperature [exothermic reaction]

Answer 13

system opposes the stress by favoring the reverse reaction

endothermic reaction absorbs heat

reaction moves to the left-hand-side

reactants are favored

equilibrium constant decreases

Question 14

pressure’s effect on equilibrium

Answer 14

no effect on equilibrium constant, only position of equilibrium

Question 15

pressure’s collision theory

Answer 15

↑pressure packs gas molecules closer together

↑frequency of collisions; thus, successful collisions

↑rate of reaction

Question 16

increase pressure

Answer 16

favors the side of least molecules

Question 17

decrease pressure

Answer 17

favors the side of most molecules

Question 18

concentration’s effect on equilibrium

Answer 18

no effect on equilibrium constant, only position of equilibrium

Question 19

catalyst’s effect on equilibrium

Answer 19

no effect on equilibrium constant nor position of equilibrium

↓activation energy (forward & reverse reaction)

↑rate of reaction (forward & reverse reaction)

↓time taken to reach equilibrium

Question 20

extent of reaction

Answer 20

how much product is formed at equilibrium

Question 21

equilibrium constant

Answer 21

expresses the relationship between reactants & products at equilibrium

(g) & (aq)

(s) & (l) do not appear in the Kc expression (unless all species in the system are liquid)

H₂O appears in the Kc expression if it is a reactant or product

Question 22

Kc > 1

Answer 22

products favored

Question 23

Kc = 1

Answer 23

reactants & products balanced

Question 24

Kc < 1

Answer 24

reactants favored

Question 25

reaction quotient

Answer 25

expresses the relationship between reactants & products at any position

relative to equilibrium

Question 26

Q > Kc

Answer 26

reactants favored

Question 27

Q < Kc

Answer 27

products favored