Rates + Equilibrium

Question 1

rate equation

Answer 1

r = K[A][B] etc.

Question 2

zero order

Answer 2

concentration have no effect on the rate

Question 3

first order

Answer 3

rate increases by same factor as concentration increases

Question 4

second order

Answer 4

rate increases by conc increase factor²

Question 5

rate units

Answer 5

mol/dm3/s

Question 6

half life

Answer 6

Time taken for half the reagent to be used up

Question 7

half life in first order reaction

Answer 7

always the same

Question 8

use of half lives

Answer 8

to determine whether or not a reaction is first order

Question 9

Arrhenius equation shows

Answer 9

effect of changing temp/activation energy on the rate constant

Question 10

Kc equation

Answer 10

Kc = [products] / [reactants]

Question 11

mole fraction equation

Answer 11

= moles of gas A \ total moles of gas

Question 12

partial pressure

Answer 12

the pressure one gas would except if it was the only gas in the container

Question 13

partial pressure equation

Answer 13

pp = mol frac. x total pressure

Question 14

only factor that changes Kc

Answer 14

temperature

Question 15

dynamic equilibrium

Answer 15

both the foward and backwards reactions are taking place, at the same rate

Question 16

dynamic equilibrium

Answer 16

both the forwards and backwards reactions are taking place, at the same rate

Question 17

effect of pressure on position of equilibrium

Answer 17

pressure increase = favours the side with fewer gas molecules (reducing pressure of the system)

Question 18

effect of temperature on position of equilibrium

Answer 18

temp increase = favours endothermic reaction

Question 19

effect of concentration on position of equilibrium

Answer 19

conc. increase = favours side with fewer moles

Question 20

Kc > 1 =

Answer 20

equilibrium position is towards PRODUCTS

Question 21

Kc < 1 =

Answer 21

equilibrium position is towards REACTANTS

Question 22

Kc = 1 =

Answer 22

equilibrium is HALFWAY between products and reactants

Question 23

heterogeneous catalyst

Answer 23

catalyst in different phase (state) to reactants

Question 24

homogeneous catalyst

Answer 24

catalyst in the same phase (state) as reactants

Question 25

how does a homogeneous catalyst work?

Answer 25

forms intermediate species which react to form products and reform the catalyst

Question 26

how does a heterogeneous catalyst work?

Answer 26

reaction occurs on its surface (therefore bigger SA = faster rate)

Question 27

rate

Answer 27

the change in the amount of reactants or production per unit of time

Question 28

Ea eq.

Answer 28

Ea = RT (ln A- Ln K)

Question 29

Arrhenius equation

Answer 29

K = Ae [to the power or] -(Ea/RT)

Question 30

gas constant

Answer 30

8.31 JK-1mol-1

Question 31

Kp eq.

Answer 31

[products partial pressure] / [reactants partial pressure]

Question 32

3 stages of contact process

Answer 32

1) sulfur solid is melted and combusted with oxygen = sulfur dioxide
2) sulfur trioxide formed from sulfur dioxide (reversible) with vanadium catalyst (exothermic) - 450 degrees C
3) sulfur trioxide reacted with oleum + conc. sulphuric acid (v. exothermic) to make sulphuric acid

Question 33

uses of H2SO4

Answer 33

• drug manufacture
• metal treatment
• paint
• making explosives

Question 34

how do catalysts reduce damage to environment? (2)

Answer 34

• reactions take place at lower activation energy ∴ less fuel used, less CO2 emitted
• better atom economy - less hazardous chemicals produced

Question 35

uses of hydrogen? (3)

Answer 35

• fuel cells
• Haber process
• hydrogenation of alkenes

Question 36

dynamic equilibrium

Answer 36

where the rate of forwards and backwards reactions are the same IN A CLOSED SYSTEM

Question 37

equation for rate constant using half lives

Answer 37

k = ln(2) / half life

Question 38

instantaneous rate

Answer 38

rate when t=0

Question 39

method for determining Kc experimentally

Answer 39

• in conical flask mix substances
• add acid catalyst
• set up another conical flask with same acid catalyst as control
• stopper both flasks
• leave for a week so they reach equilibrium
• carry out titration using NaOH
• repeat titration with control to determine amount of acid catalyst used
• analyse to determine eq amounts and concs
• use kc equation

Question 40

catalyst

Answer 40

a species which speeds up a reaction w/o undergoing permanent change itself

Question 41

le Chatiliers principle

Answer 41

when a change is imposed on a closed system at equilibria, the position of the equilibrium will shift to minimise the effect of the change

Question 42

temp increase favours

Answer 42

ENDOTHERMIC

Question 43

temp decrease favours

Answer 43

EXOTHERMIC

Question 44

Kc =

Answer 44

[products] / [reactants]

Question 45

Kc > 1 =

Answer 45

eq. towards PRODUCTS

Question 46

Kc < 1 =

Answer 46

eq. towards REACTANTS

Question 47

K =

Answer 47

rate / [A]2

Question 48

methods of continuous rate monitoring (2)

Answer 48

• gas collection

- mass lost

Question 49

K = (using t 1/2)

Answer 49

ln2. /t 1/2

Question 50

effect of temp on Kc - (temp up =)

Answer 50

rate up = Kc UP

Question 51

Kp =

Answer 51

partial pressure (products) / pp. (reactants)

Question 52

conc increase favours…

Answer 52

side producing fewer moles

Question 53

conc decrease favours

Answer 53

side producing more moles

Question 54

if K is negative ..

Answer 54

towards reactants

Question 55

is K is positive …

Answer 55

towards products