How fast 5.1.1

what are the units for rate

mol dm⁻³s⁻¹

What is the rate expression?

what is the unit for Concentration

mol dm⁻³

what are the two types of graphs

Concentration ( mol dm⁻3) / Time (s) graph

Rate ( mol dm⁻3 s⁻1) / Concentration ( mol dm⁻3) graph

Zero order Graph —> Rate / Conc

First order graph —> Rate / conc

2nd Order graph —> Rate/ conc

what does Zero order mean

changing concentration has no effect on the rate

rate stays the same

what does first order mean

Rate ∝ [ x ]¹

what does 2nd Order mean

Rate ∝ [ x ]²

Should you include Zero order in rate equation?

No ( ignore it )

temperature increasing effect on K

K increases

what does a larger K result in

Faster rate

how to work out overall order

add the orders together

[ x ] = ¹

what are units of 0 order overall

mol dm⁻³ s⁻¹

what are the units of 1st order overall

s⁻1

what are the units for 2nd order overall

s⁻¹mol⁻¹dm³

what are the units for 3rd order overall

s⁻¹mol⁻²dm⁶

what does half life mean?

time taken for the concentration to half

what is the rule for the half life of a 1st order reaction

constant half life

examples of constant half lifes

Radioactive decay

Pharmacokinetics of drugs

Zero order concentration/ time graph

First order concentration/ time graph

First order half life graph ( Image)

Rule for 2nd order half life

As concentration decreases, half life increases

2nd Order half life graph ( Image)

Rule for Zero order half life

As concentration decreases , half life decreases

Zero order half life ( image)

Initial rates questions which experiments to use?

other reactants concentration are constant / the same

what are the Arrhenius equations

what does K represent in the Arrhenius equation

Rate constant

what does Ea represent in the Arrhenius equation

Activation energy ( J mol⁻¹ )

how to convert from KJ to J

x1000

how to convert from J to KJ

/1000

what does T represent in the Arrhenius equation

Temperature (K)

what does R represent in the Arrhenius equation

8.31 ( constant)

what does A represent in the Arrhenius equation

exponential factor

same units as Rate constant

what is the effect of increasing Ea on the rate constant

As Ea increases, K gets smaller

what is the effect of decreasing Ea on the rate constant

K increases

what is the effect temperature increasing on rate constant

K increases

why does Rate increase as temperature increases

kinetic energy if particles increases —> Faster moving particles —> many more particles have energies greater then the Activation energy —> more frequent and successful collisions.

which Arrhenius equation to use when working out any of the powers ( Ea / R/T )

which Arrhenius equation to use when working out A

Explain qualitatively why increasing temperature has a greater effect then increasing concentration

reactions occur when particles have energy greater then the activation energy

increasing temperature causes many more particles to have energy greater then the Ea

increasing concentration increases number of particles with the energy

Arrhenius plots ( Image)

what are the Y and X axis for Arrhenius plot and units

Y=  In K

X= 1/T ( K⁻¹)

Arrhenius equation to work out Plots

method for working Ea in kjmol⁻¹ ( Arrhenius plots)

1) plot the graph X = 1/T ( K⁻¹) Y = In K

2) work out the gradient ( dy/dx)

3) Gradient x ( -8.31) = Ea ( J mol⁻¹)

/1000 = Kj mol⁻¹

How to convert from J mol⁻¹ to KJ mol⁻¹

/1000

How to convert from KJ mol⁻¹ to J mol⁻¹

X 1000

How to work out A ( Arrhenius equation)

Y intercept value (  point Line of best fit crosses Y axis) = In K

( -EA / RT) - ( In K) = In A ( x)

e× 

how to work out A in Arrhenius plots ( Image)

To work out T = 1/T

what is the rate determining step

the slowest step in a reaction 

what is the rate equation and orders for this reaction

A + 2B → X + Y

Rate = K [ A] [ B]²

First order → A

Second order → B

In R.D.S rate equation what does the Order show

the molar ratio of a reactant ( how many of the reactant there is )

Working out R.D.S method ?

The R.D.S and Step 2 equation =  the overall equation 

only the products and reactants from R.D.S and Step 2 can cancel out 

Product from step 2 and overall equation has to be the same  

to work out the R.D.S products = combine the reactants !!!!

overall equation has more then 1 mole of reactant → both equations reactant ( both contain 1 mole of reactant) add up to make moles of reactant

If step 2 and R.D.S cancel to make overall equation = Correct

maximum of 2 reactants in step 2

what is the catalyst in a R.D.S equation

catalyst is a Reactant that gets reformed as a product after getting consumed in the previous equation

what is the intermediate in a R.D.S

A reactant that gets formed in the first step then consumed in the second step

Why is excess other reactant used in ( calculate order of reaction experiments)

keep the reactant constant 

2 ways to measure volume of gas

Gas syringe method

measure mass loss of reactant

suggest apparatus that allows volume of gas to be collected ( with scales of working

1000cm³/ 1 dm³ measuring cylinder

why does absorbance decrease in reactions with colorimeter

limiting reactant gets used up

the products are colourless 

method to working out how to obtain concentrations from experiments

mix 10cm³ of each( named) reactant

dilute each solution with water 

total volume is control variable 

how to tell if ions are acting as catalyst

catalyst → ion is regenerated

standard form / incorrect past paper question ( IMAGE)

R.D.S is the overall equation apart of the steps in mechanism?

no overall equation isn’t a step

reasons why it is unlikely for R.D.S reactions to occur in one step

collisions are unlikely with more then 2 species

rate equation doesn’t match overall equation

how to monitor concentration of reactant in conc/time graph

use colorimeter to measure reduction of colour of ( named) reactant 

how to work out K in half-life for first order equation

In(2) / time

Reasons why conditions are different in industry

High temp → High energy usage

Low pressure → Slow rate of reaction