Summary A2 Unit 1: Chemical Kinetics

DefiningRate
Rate
of Rn the
A positive number thatdescribeshowquicklythe concentrations of
reactants l
products change during the run


Rate
of An is determined
by finding the gradientof a

core timegraph


Reactant
an

T.fi nraea TEEn
initial time
Product
rate is certain point in time
fixedfor
i
a
conc
As conc change on progress
ratelange



rate of an
oe
time Δg
moldm 35
initial
rate

Average rate
Whitehead

, Rate formation l removal
of
24202 cags 2H20 it_02 cg
there is 2 moles of water formedfor every one mole
of oxygen
this means water is formed twice as
fast as oxygen
water is twice the
of formation of
i rate
rate formation
of of oxygen
rate
of formation of 02 SOI
Δt
rate
offormation of H2O ΔEIz
also 2
III
2 moles of hydrogen peroxide decomposes for every
mole
of oxygen formed
therefore hydrogen peroxide decomposes twice as fast as
oxygen is formed
rate
of removal of hydrogen peroxide
twice rate
is
of formation of oxygen
rate Δ 3 1
of removal 4202 Hz
2
23
used tochange decrease
of
HerePositivedeterminate rate of removal

, of 2


rate of removal rate of an


24202 2H20 02
rate offormation of02 I rate ran
of
rate formation of H2O 2 rate
rate
of rate
of run

of removal 1202 2
of of An


Example
Dinitrogen pentoxide N20s decomposeswhen heated When a
sample of N 0s with a conc 0.002 moldm 3 is heated the
ofobserved 6
rate disappearance N is to be 1.1 10 molden35
of
Calculate
0s
arate of ran 2NzOsig 20204cg 02cg
b rate formationof oxygen
of
under these conditions


a rate of removal Ngos
6
rate of an balancing number
1.1 10 rate ran 2
rate run
of 6
of 1.110
7
5.5 10 mol dm 5

b rate rate of ran
of formation of 02 5 5 10 7
balancing no
1
35
0tmdm