3.2.2 Reaction rates & 3.2.3 Equilibrium

Question 1

collision theory

Answer 1

minimium amout of energy between them and they must collide with the correct orientation for reaction to occur

Question 2

rate of reaction definition and units

Answer 2

rate at which reactants are converted into products
mol dm-3 s-1

Question 3

activation energy

Answer 3

minimium amount of energy required to start the reaction by the breaking of bonds

Question 4

rate equation

Answer 4

change in concentration / time

Question 5

factors affecting rate

Answer 5

concentration
temperature
surface area
catalyst
pressure

Question 6

how does increasing concentration affect rate

Answer 6

more particles present per unit volume so particles collide more frequently

Question 7

how does increasing temperature affect rate

Answer 7

particles have more kinetic energy so they collide more with more energy so a greater proportion of collisions have energy greater than the activation energy

Question 8

how does increasing surface area affect rate

Answer 8

more particles are exposed for collisions and so they collide more frequently

Question 9

how does a catalyst affect rate

Answer 9

provides alternative reaction pathway with a lower activation energy so a greater proportion of the collisions have energy greater than the activation energy

Question 10

how does increasing pressure of gas affect rate

Answer 10

more particles present per unit volume so particles collide more frequently

Question 11

homogenous catalyst

Answer 11

catalyst is the same state as reactants

Question 12

heterogenous catalyst

Answer 12

catalyst is a different state to reactants

Question 13

benefits of a catalyst in terms of money and sustainability

Answer 13

catalyst provides alternative pathway with lower activation energy so reduces temp required so less electricity and fuel used so increase profitibility
uses less fossil fuels so reduces emmission of CO2 linked to global warming so increase sustainability

Question 14

features of the Boltzmanns distrubution

Answer 14

no molecules have zero energy
area under the curve is equal to the total number of molecules
theres no maximium energy for a molecule as curve does not meet x axis at high energy

Question 15

methods for following progress of chemical reactions

Answer 15

monitor removal of reactant or formation of product

Question 16

method for monitoring reaction producing gas

Answer 16

monitor volume of gas produced using gas cylinder at certain intervals or in a specific time
monitor loss of mass of reactants using mass balance

Question 17

what happens to the boltzmanns distrubution if you increase the temperature

Answer 17

graph will strech over greater range of energy values as more molecules will have a higher energy

Question 18

what happens to the area under the curve of the boltzemanns distrubution if you increase the temperature

Answer 18

stays the same

Question 19

Factors affecting equilibrium

Answer 19

concentration
catalyst
pressure
temperature

Question 20

how does increasing the concentration of N2 affect how ammonia is produced
(3H2 +N2 <-> 2NH3)

Answer 20

forward reaction is favoured as theres more reactants so they want to use them up

Question 21

how does increasing the pressure affect how ammonia is produced
(3H2 +N2 <-> 2NH3)

Answer 21

favours forward reaction as it moves to the side with fewer moleules to minimise the increase in pressure

Question 22

how does increasing the temperature affect how ammonia is produced
(3H2 +N2 <-> 2NH3)
-exothermic reaction

Answer 22

favours backwards reaction as its endothermic direction so takes the energy in

Question 23

how does adding a catalyst affect how ammonia is produced
(3H2 +N2 <-> 2NH3)

Answer 23

affects both forward and backwards reaction but equilibrium will be reached faster

Question 24

Le Chatelier’s principle

Answer 24

if system at equilibrium is disturebed by changing the conditions the position of equilibrium moves in the direction that counteracts the change

Question 25

conditions of an equilibrium system

Answer 25

rate of forward reaction = rate of reverse reaction
concentration of products and reactants doesn’t change
must be in a closed system

Question 26

Kc

Answer 26

[products] / [reactants]

Question 27

what do the [ ] mean

Answer 27

concentration

Question 28

N2 + O2 <-> 2NO
Kc equation

Answer 28

[NO]^2/ [N2][O2]

Question 29

what position is equilibrium if Kc> 1

Answer 29

towards the products so forwards reaction

Question 30

what position is equilibrium if Kc<1

Answer 30

equilibrium is towards the reactants

Question 31

what position is equilibrium if Kc=1

Answer 31

equilibrium is halfway between reactants and products