Rates Of rXn's

Question 1

Things that affect r.o.r

Answer 1

Prescience of cats
Nature of reactants
Temperature
Concentration
Particle size

Question 2

Homogeneous catalysis

Answer 2

Reactants & products in same phase

H2o2——-KI——-H2o & 1/2 O2

Question 3

Heterogeneous

Answer 3

Not same phase
Oxidation of methanol
H202 ——mno2—–h20 & 1/2 o2

Question 4

Oxidation of methanol

Answer 4

Observe: Heat given out & platinum glows
Products : H2 methanal h2o
Surface adsorption?

Question 5

Autocatalysis

Answer 5

Catalyst is product
Titration first drops of kmno4 decolourised slowly. others faster
Mn+2 = catalyst

Question 6

Intermediate formation theory

Answer 6

Catalyst reacts with 1 of reactants
Forms intermediate
Intermediate reacts with other reactant
Final product
h202——-I(minus)——-h20 & 1/2 o2 (iodine snake)
Oxidation of potasium sodium titrate by cobalt cl & h202

Question 7

Oxidation of pot, na tartrate by h202 & cobalt cl

Answer 7

Pink-> green Formation of new Compound
Bubbles. Intermediate reacting
Green-> pink. Substance that was formed was an intermediate

Question 8

Surface adsorption

Answer 8

H2 & o2 settle on platinum surface
Inreased con. More likely to collide

Collide and form h20

Product leaves surface

Question 9

Catalytic converters

Answer 9

Lead- absorbed strongly by c.c blocks catalyst prevents from working source=Leaded petrol
Harmful to LESS HARMFUL
Co->co2
Nox-> n2 & o2
Unburned hydrocarbs-> h2o & co2

Question 10

Co
Nox
Unburned hydrocarbons. Affects

Answer 10

Co- poisonous toxic tasteless odourless gas
Nox - toxic lead to acid rain
U.h- lead to smog

Question 11

Assumption of collision theiry

Answer 11

To react reacting particles must collide
These collisions only form products if a certain minimum energy is exceeded this is an EFFECTIVE COLLISION
R.O.R depends on number of collisions and effective collisions

Question 12

Activation energy

Answer 12

Minimum amount of energy needed by colliding particle in order for them to react
Graph- difference between average energy of the molecules and energy of molecules at activated complex

Question 13

Why rXns faster at higher temps?

Answer 13

More collision occur

NB particles colliding have have the min. Activation energy needed to react

Question 14

Exothermic vs endothermic

Answer 14

Exo- less heat given out by product than reactants

Endo- more heat given out by product

Question 15

Particle size , ROR, collision

Answer 15

Smaller particle size-> more collisions-> more effective collisions
As smaller particles have more surface area available for reacting

Question 16

Catalyst

Answer 16

Substance that alters rate if rXn without being consumed / altered itself by reaction

Small amount needed
Specific
Not changed

Question 17

Specifity of catalysts

Answer 17

Lipase on lipids

Pepsin on protein

Question 18

R.o.r

Answer 18

change of conc. per unit time of any 1 reactant or product