Equilibria

Question 1

What does K stand for ?

Answer 1

Equilibrium constant

Question 2

What does Kc stand for

Answer 2

Equilibrium constant using concentration

Question 3

What does Kp stand for

Answer 3

Equilibrium constant using pressure

Question 4

What does [ ] represent

Answer 4

Concentration

Question 5

Mole fraction of a gas =

Answer 5

Moles (gas) / total moles (gas) in mixture

Question 6

Partial pressure of a gas =

Answer 6

Mole fraction (gas) x total pressure

Question 7

what is dynamic equilibrium ?

Answer 7

RATE forward reaction = RATE back wards reaction (conc of reactants and products stay constant)

Question 8

Give Le Chatelier’s principle for concentration

Answer 8

increasing conc of reactants will make more product (vice versa) - decreasing conc has opposite effect

Question 9

Give Le Chatelier’s principle for pressure

Answer 9

increasing pressure shifts equilibrium to side with fewer GAS molecules

Question 10

Give Le Chatelier’s principle for temperature

Answer 10

increasing temp will shift equilibrium in endothermic direction

Question 11

how do catalysts affect equilibrium ?

Answer 11

cannot affect position of equilibrium, however they do cause equilibrium to be reached faster

Question 12

what is the Kc expression ?

Answer 12

aA+bBdD+eE
[D]^d[E]^e
————–
[A]^a[B]^b

Question 13

The larger Kc is …

Answer 13

the further to right equilibrium lies

Question 14

The smaller Kc is …

Answer 14

the further to left equilibrium lies

Question 15

a dynamic equilibrium can only happen if …

Answer 15

system is closed and temp is constant

Question 16

what is a homogeneous reaction ?

Answer 16

all the reactants and products are the same

Question 17

what is a heterogeneous reaction ?

Answer 17

products and reactants in different states

Question 18

what substances apply to the Kc expression ?

Answer 18

only gaseous and aqueous substances (not liquids/solids)

Question 19

define total pressure

Answer 19

sum of all the partial pressures of individual gases

Question 20

what does p( ) represent ?

Answer 20

partial pressure of …

Question 21

Kp =

Answer 21

p(A)^a p(B)^b

Question 22

what changes the equilibrium constant ?

Answer 22

temp

Question 23

if temp shifts equilibrium to left, what happens to equilibrium constant ?

Answer 23

constant decreases

Question 24

if temp causes equilibrium to shift to right, what happens to equilibrium constant ?

Answer 24

constant increases

Question 25

Kc and Kp are only affected by …

Answer 25

temperature

Question 26

state two features of a system that is in dynamic equilibrium

Answer 26

rate of forwards = rate of backwards

concentrations are constant but constantly interchanging

Question 27

when describing equilibrium what word to use ?

Answer 27

favours

Question 28

state le Chatiliers principle

Answer 28

when the conditions on a system in equilibrium are changed, the equilibrium moves to minimise the effects of the change