module 3: equilibrium

Question 1

rate =

Answer 1

concentration/ time

Question 2

rate of reaction calculated by

Answer 2

reactant us up/ product formed overtime

if gas produced increase of in volume, decrease in mass
if reactant acid increase in pH over time

Question 3

collision theory

Answer 3

particles collide with enough energy to break existing bonds
collide in correct orientation
not all collisions are successful
higher rate = more successful collisions per second

Question 4

increasing concentration

Answer 4

increases the rate of reaction
more particles per unit volume
more frequent collisions

Question 5

rate of reactions from graphs

Answer 5

instantaneous -> tangent

Question 6

catalyst

Answer 6

increases rate of reaction without being used up
lowers activation energy by providing an alternate pathway
“proceed via alternate route with lower activation energy”

Question 7

homogeneous catalyst

Answer 7

same state as reactants

Question 8

heterogeneous catalyst

Answer 8

different state from reactants

Question 9

benefits of using catalyst

Answer 9

lower temperature and pressure
reduce energy demand -> less fossil fuels burnt -> less limited resources used up and CO2 produced
increases sustainability and reduces emissions
cost saving

Question 10

Boltzmann distribution key notes

Answer 10

not symmetrical
does not cross x-axis (asymptote)
starts at origin, no particles have zero energy
total area= total number of gas particles

Question 11

Boltzmann curve Ea

Answer 11

larger area= greater proportion of particles with an energy greater than Ea therefore faster rate of reaction

Question 12

Boltzmann distribution temperature graph aided

Answer 12

higher temperature peak lower and shifted right
greater proportion of molecules can overcome activation energy

Question 13

Boltzmann distribution temperature

Answer 13

as temperature increases
average energy of particles increases
peak distribution moves right
flatter
greater proportion of molecules can overcome activation energy
rate of reaction increases

Question 14

Boltzmann distribution catalysts

Answer 14

distribution curve same
activation energy lower
greater proportion of molecules exceed new lower activation energy
on collision, more molecules react to form products
rate of reaction increases

Question 15

Le Chateliers principle

Answer 15

system works to counteract change

Question 16

dynamic equilibrium

Answer 16

closed system
rate of forward reaction= rate of reverse reaction
concentration of reactants and products remain constant

Question 17

increasing temperature

Answer 17

endothermic reaction favoured

Question 18

changing concentration

Answer 18

equilibrium shifts to oppose change

Question 19

factors affecting rate of reaction

Answer 19

concentration
surface area
temperature
pressure
catalyst

Question 20

pressure same no of moles on both sides

Answer 20

no change

Question 21

increasing pressure

Answer 21

favours side with fewer moles of gas

Question 22

heterogeneous catalysts notes

Answer 22

reactants absorbed onto surface
weak bonds formed between reactants and catalysts
bonds between reactant molecules weaken and break
new bonds form between reactant molecules

Question 23

catalyst “poisoning”

Answer 23

impurities bind to the surface
e.g. lead and sulfur

Question 24

regeneration

Answer 24

blowing hot air over a catalyst
oxidises chemicals on the surface
used to remove carbon after catalytic cracking

Question 25

Kc =1

Answer 25

equilibrium position around halfway between reactants and products

Question 26

Kc < 1

Answer 26

equilibrium favours reactants

Question 27

Kc >1

Answer 27

equilibrium favours products
(high concentration of products to reactants)

Question 28

homogeneous equilibrium

Answer 28

reactions in which reacting species are in the same phase

Question 29

heterogeneous equilibrium

Answer 29

different phase
solids and liquids do not appear

Question 30

equilibrium constant

Answer 30

[A] (concentration of reactants) decreases to a constant
[B] (concentration of products) increases from zero to a constant

no matter the starting composition of reactants and products, the same ration is achieved at equilibrium at constant temperature

Question 31

catalyst equilibrium position

Answer 31

no effect-> forward and reverse both increased by same amount
equilibrium reached faster

Question 32

Ea

Answer 32

minimum energy for reaction to occur

Question 33

equilibrium law

Answer 33

for the reaction aA + bB ⇌ cC + dD

kc = ([C]c [D]d) / ([A]a [B]b)

kc is in terms of concentration

Question 34

equilibrium law simplified

Answer 34

Kc= [products]/ [reactants]

Question 35

when equation for reversible reaction given in opposite direction

Answer 35

equilibrium constant becomes resiprocal