OCR A 5.1.1 How Fast

(incomplete) without PAG

how to find rate from change and time graph

-gradient of line of best fit

when curved:

-draw tangent to point where asked for

rate equation linked with conc of substances

rate unit

moldm^-3

how to find order of reaction

add up powers

zero order

change in conc no effect on rate

1st order

2nd order

rate constant (k)

-allows to equate rate and conc

-fixed at particular temp

-if temp change so does k

-larger k is faster RoR

what order

0: as conc increases rate doesnt

what order

-1st: straight line thru origin

-first graph: Prove that half life exists

-as conc changes rate changes equally

what order

-2nd

-rate changes in unequal amounts

-changing conc changes rate sqrd

half life

time taken for half of reactants to be used up

how to calc k from conc time graph

-find half life

k= ln2/halflife

units= s^-1

rate determining step

-slowest step in multi step reaction

-this determines whole reaction rate

-reactants that effect RoR must be in this step

-catalysts can be in too

which reactants effect rate

reactants in rate equation

arrhenius equation

-links E_a and temp to rate constant

as E_a decreases what happens to k

k increases

as temp increases what happens to k

k increases

arrhenius eqtaution to find E_a

arrhenius plot axis label

-x: 1/t

-y: lnk

arrhenius plot find E_a

-draw lob

-gradient = -E_a/R

-E_a = 8.31 x gradient

arrhenius plot find Arrhenius consatnt

-sub any coordinate and gradient into equation