Rate equations
calculating rate from graph initial rate tangent at O minutes
rate found from gradient grad ay An
curved line of best fit rate gradient of a tangent
units for rate units for y units for n
rate equation links rate with conc of substances
e.gl At B C t D orders of reaction substances with ZER
oldm 3s I
Rate K A
f
TBI conc of reactants
order do not appear in
rate equation
ate constant unitsvary
orders of reaction tells how conc of substance affects rate
zero order change in conc has NO EFFECT on rate
e g if A doubles rate does not change
1st order changein conc has PROPORTIONAL change on rate
e gl if AT doubles rate doubles
2nd order change in conc has a SQUARED PROPORTIONAL change on
ate he.gl if CA doubles rate quadruples
can only be determined by experiment
rate constant k allows us to equate rate and conc
fixed at a particular temp if tempchanges sodoes K K increase
hen temp increases larger value of k faster rate because as we
crease tempparticles have more kinetic energy and collide more often
ate increases butconc remains constantso k mustincrease to balance equation
working out units sub units into equation cancel units that appea
n top and bottom invert any that are left on the bottom
e gl k rate Units MOldM3S I Mol dm35 I
No 2 moldm3 mold m3
initial rates can be usedto work out the orders and write a rate equation
working out order with respect A compareexperiments where CATis
hanging and CB is constant
k has same value for all experiments of a reaction
use initial rate and initial conc of reactants to calculate K
K can then be used to then calculate any unknown conc or rate
rate table has a substance where conc does not stay same
e g Experiment A CBI rate
0.150.240.42 10 3
31 0.450.243.78 10 3
0.90 0.12 7.56 10 3
find orderx with respect to a usingexperiments 1 and 2
CAT has 3 and rate has x9 so order 2
substitute order with respect to a into rate equation with
one and rate and divide two equation to cancel out k find missing
r den with respect to B find k write rate equation
now rates can be measured in experiments
disappearing cross i
change in pit CifHt is usedup or produced
amount of mass lost colourchangemeasuredusing colorimete
volume of gas produced
using rate conc graphs to identify order
rate found bytakinggradient at various points on a conc time graph
straightlinegraph shallow curve steep curve
calculating rate from graph initial rate tangent at O minutes
rate found from gradient grad ay An
curved line of best fit rate gradient of a tangent
units for rate units for y units for n
rate equation links rate with conc of substances
e.gl At B C t D orders of reaction substances with ZER
oldm 3s I
Rate K A
f
TBI conc of reactants
order do not appear in
rate equation
ate constant unitsvary
orders of reaction tells how conc of substance affects rate
zero order change in conc has NO EFFECT on rate
e g if A doubles rate does not change
1st order changein conc has PROPORTIONAL change on rate
e gl if AT doubles rate doubles
2nd order change in conc has a SQUARED PROPORTIONAL change on
ate he.gl if CA doubles rate quadruples
can only be determined by experiment
rate constant k allows us to equate rate and conc
fixed at a particular temp if tempchanges sodoes K K increase
hen temp increases larger value of k faster rate because as we
crease tempparticles have more kinetic energy and collide more often
ate increases butconc remains constantso k mustincrease to balance equation
working out units sub units into equation cancel units that appea
n top and bottom invert any that are left on the bottom
e gl k rate Units MOldM3S I Mol dm35 I
No 2 moldm3 mold m3
initial rates can be usedto work out the orders and write a rate equation
working out order with respect A compareexperiments where CATis
hanging and CB is constant
k has same value for all experiments of a reaction
use initial rate and initial conc of reactants to calculate K
K can then be used to then calculate any unknown conc or rate
rate table has a substance where conc does not stay same
e g Experiment A CBI rate
0.150.240.42 10 3
31 0.450.243.78 10 3
0.90 0.12 7.56 10 3
find orderx with respect to a usingexperiments 1 and 2
CAT has 3 and rate has x9 so order 2
substitute order with respect to a into rate equation with
one and rate and divide two equation to cancel out k find missing
r den with respect to B find k write rate equation
now rates can be measured in experiments
disappearing cross i
change in pit CifHt is usedup or produced
amount of mass lost colourchangemeasuredusing colorimete
volume of gas produced
using rate conc graphs to identify order
rate found bytakinggradient at various points on a conc time graph
straightlinegraph shallow curve steep curve
