Kinetics

Front 1

what effect does an increase in temperature have on the rate of a reaction

Back 1

inc in average kinetic energy

so more particles meet activation energy requirements

so more successful collisions.

as closer togther

Front 2

what effect does a catalyst have on rate of reaction

Back 2

lowers activation energy by providing an alternate pathway with lower activation energy. have no effect on position of equilibrium

Front 3

equation for rate of reaction

Back 3

change in products or reactants / change in time= rate

Front 4

what does the rate expression tell us

Back 4

it is an equation that describes how the rate of the reacion at a particular temperature depends on the concentration of species involves in the reaction

Front 5

how can the details of how each species contribute be found out

Back 5

by experiement only

Front 6

what does this show

rate= k [X][Y]2

Back 6

it shows that on doubling X the rate of reaction will double as rate is proportional to the concentration of X and that doubling Y will quadruple the rate of reaction as rate is proportional to the square of Y

Front 7

what is K

Back 7

the rate constant for the reaction

Front 8

what is the order of a reaction

Back 8

with respect to one of the species si the power to which the concentration of that species is raised in the rate expression.

Front 9

what is the overall order of a reaction

Back 9

this is the sum of the orders of all the species which appear in the rate expression

Front 10

units of rate

Back 10

mol dm-3 s-1

Front 11

units of K for a first order reaction

Back 11

s-1

Front 12

units of K for a second order reaction

Back 12

mol-1 dm3 s-1

Front 13

units of K for a third order reaction

Back 13

mol-2 dm6 s-1

Front 14

if rate is not affected by concentration of species

Back 14

zero order

Front 15

if rate is directly proportional to concentration of species

Back 15

first order

Front 16

if ratei s directly proportional to square of the concentration of the species

Back 16

second order

Front 17

if graph has a horizontal straight line

Back 17

zero order

Front 18

if graph has a sloping straight line through origin

Back 18

first order

Front 19

if graph is not a straight line

Back 19

cannot find the order directly

it could be 2

Front 20

what is the initial rate method

Back 20

series of experiments diff temperatures

each with a diff combo of reactants

planned so con of only one species varies at a time

comparing the intial concentration and the initial rates for pairs of experiements allows order of each reactant to be found

Front 21

to work out K

Back 21

rate / [X][Y]2 (so the con of the reactants in rate equation)

Front 22

effect of temp on K

Back 22

increase temp increases rate of reaction

K is different for every reaction and varies with temperature. so temp it was measured should be stated.

Front 23

why does K depend on temperature

Back 23

temp measure of avg kinetic energy

particles only react if have enough energy to break bonds

as temp inc greater proportion of molecules have enough energy to react.

Front 24

what is the rate determining step

Back 24

the slowest step

Front 25

what effect do the reactions occuring after the rate-determing step have

Back 25

no effect on the rate of reaction