Kinetics ll

Question 1

What are the techniques to investigate rates of reaction?

Answer 1

1. Change of mass - works better when gas escapes
2. Titration
3. Colorimetry
4. Measurement

Question 2

What kind of titration do you do when you investigate rates of reaction?

Answer 2

• Samples are removed from titration
• Sample is quenched (a way of stopping the reaction)
• Titrated again

Question 3

What is the rate of reaction equation?

Answer 3

rate = k[A]^m[B]^n

m and n relate to the order of the reaction
[] is the concentration of the reactant

Question 4

What are the units for the rate of reaction?

Answer 4

moldm^-3s^-1

Question 5

What does it mean is a reactant has 0 order?

Answer 5

The concentration of the reactant has no impact on the rate

Question 6

What does it mean if a reactant has an order of 1?

Answer 6

The concentration of the reactant is directly proportional to the rate

Question 7

What does it mean if a reactant has an order of 2?

Answer 7

The rate is proportional to the square of the reactant concentration

Question 8

If half-lives are constant, what order is the reactant?

Answer 8

1

Question 9

If half-lives rapidly increase, what is the order of the reactant?

Answer 9

2

Question 10

What is the overall order of a reaction?

Answer 10

The sum of all the orders

Question 11

What is k in the rate equation?

Answer 11

rate equation constant

Question 12

What is k affected by?

Answer 12

Temperature - increasing temperature increases value of k

Question 13

What is k the same for?

Answer 13

All experiments at the same temperature?

Question 14

What is the overall rate of reaction dependent on?

Answer 14

The slowest step

Question 15

What is the slowest step known as?

Answer 15

The rate determining step

Question 16

How do you determine the rate determining step?

Answer 16

The step that includes all species from the rate equation in the correct ratios

Question 17

What does not appear in the rate equation?

Answer 17

Species that are involved in steps after the rate determining step

Question 18

What order overall is the hydrolysis of a primary halogenoalkane?

Answer 18

2nd order

Question 19

Why is the hydrolysis of a primary halogenoalkane overall 2nd order?

Answer 19

It is an SN2 mechanism so 2 reactants coming together

Question 20

What order overall is the hydrolysis of a tertiary halogenoalkane?

Answer 20

1st order

Question 21

Why is the hydrolysis of a tertiary halogenoalkane overall 1st order?

Answer 21

SN1 so 1 molecule in the RDS

Question 22

What is the Arrhenius equation?

Answer 22

lnK = lnA - Ea/RT

k = Ae^-Ea/RT

Question 23

What are all the constants in the Arrhenius equation?

Answer 23

k = rate constant
A = Arrhenius constant
R = 8.31
T = temperature (kelvin)
Ea = Activation energy (in the equation should be converted to Joules)

Question 24

What does the gradient of a lnk by 1/T graph represent?

Answer 24

The activation energy divided by R
Ea/R

Question 25

What is found on the x and y axis of a rate graph using the Arrhenius equation?

Answer 25

on the x axis is 1/T on the y axis is lnk

Question 26

How do you calculate the activation energy from an Arrhenius graph?

Answer 26

-gradient x R The gradient will be in J/mol so we divide it by 1000