AC2: Reaction Kinetics II Flashcards
What order is A if the concentration doubles and the rate also doubles
First order
What order is A if the concentration doubles but the rate quadruples
Second order
When the equation is Rate=[A][B], what is the overall order, and what is the order for A and what is the order for B
Second order overall since A and B are both first order (1+1=2). First order in concentration of A and first order for concentration of B
What is the rate equation, involving A & B, if the overall order was 4 and the order of A was second
Rate=k[A]^2[B]^2
Both are second order since 2+2=4
When solving k what is always the most important thing to remember
The unit
What would happen to the rate if [A] was tripled
Rate=k[A]^2
Rate increases x9
What would happen to the rate if both A and B were doubled
Rate=k[A][B]^2
If A doubles the rate doubles, x2, and if B doubles the rate quadruples, x4, so rate increases by a factor of 8
What is the name of the slow step in chemical reactions
Rate determining step
What are the 2 rules of stepwise mechanisms
- The rate equation only includes reacting species involved in the rate determining step
- The orders in the rate equation match the number of species involved in the RDS
A->B->C reaction, what is the name of B, something that is created and destroyed in the reaction
Intermediate
When creating your own mechanism, what is the final step to do to check it’s the same as the chemical equation
Add up the LHS and add up the RHS
What is the name of a reactant that isn’t used up in the chemical equation but is regenerated in the final step of the mechanism
Catalyst
Explain what happens to the rate of reaction when the temperature increases (5 marks)
- Draw Boltzmann distribution curve
- Draw a second line on the curve to show the hotter temperature
- Higher proportion of particles with energy above the activation energy
In the Arrhenius equation, what does the k stand for
Rate constant
In the Arrhenius equation, what does the A stand for
Pre-exponential factor
In the Arrhenius equation, what does the Ea stand for
Activation energy
In the Arrhenius equation, what does the R stand for
Gas constant
In the Arrhenius equation, what does the T stand for and what are the units
Temperature and Kelvin units
if the temperature raises by 10 degrees, by what factor does the rate constant roughly increase by
2 / it roughly doubles
Using the Arrhenius equation, but the lnk=version, what part of the given equation in, the formula sheet is equal to the y in y=mx+c
the lnk
Using the Arrhenius equation, in the form lnk= what part equals the m in y=mx+c
the -Ea/ R
Using the Arrhenius equation, in the form lnk=, what part equals the x in y=mx+c
the 1/T
Using the Arrhenius equation in the form lnk=, what part equals the c in y=mx+c
lnA
When reading info from an Arrhenius plot, what is equation to the gradient
-Ea/R
When reading info off the Arrhenius plot, what is the unit straight off the graph for Ea
Jmol ^-1 / joules per mole
How do you convert joules per mole to kJ per mole
divide by 1000
What is the crucial thing to remember when calculating the gradient from an Arrhenius plot, to do with the actual x / y values
Check to see if the values are x10^of something. Then before calculating the gradient make sure you include the factor of 10 it might be
After plotting an Arrhenius plot, what is the next thing to do in order to calculate the gradient
Draw line of best fit
What does the A, in the Arrhenius equation demonstrate
The orientation of the particles colliding
How do you find A from the Arrhenius plot
The y intercept =lnA
Then do e to the power of the intercept to find A
What is the unit of A
The same as the unit for k
Why is the unit for A the same as the unit for k
Because the Arrhenius equation is k=Ae^-Ea/RT, and the e^-Ea/RT is unitless- leaving k=A for the units
Is the Ea for a reaction involving iodocyclopentane higher or lower than the Ea for a reaction involving chlorocyclopentane
Ea is lower for the reaction with iodocyclopentane since the C-I bond is weaker than the C-Cl bond therefore less energy is required to overcome the bond
Weak answer: Alkenes react via electrophilic substitution , what is the improved/ corrected answer
Alkenes react via electrophilic addition
Weak answer: Pentan-2-ol undergoes elimination to form pent-1-ene and pent-2-ene
Isomers of pent-2-ene E/Z
