Reaction Kinetics

Question 1

What does kinetics mean?

Answer 1

things related to the rate of reaction

Question 2

What is the rate of reaction?

Answer 2

the rate of change of concentration of a reactant or product with time

Question 3

What are the units for rate?

Answer 3

moldm-3 s-1

Question 4

What are the 2 ways that rate can be measured?

Answer 4

1. samples taken at interval time points
2. continuous monitoring of the reaction

Question 5

How does a colorimeter work?

Answer 5

uses a filter to select light in a wavelength range where there is a big difference in strength of absorptio by the products compared to the reactants

Question 6

What is the method of monitoring a reaction using colorimetry?

Answer 6

1. select filter for an appropriate wavelength
2. calibrate the colorimeter by measuring absorbance rate of standard solutions with known concs of the coloured substance
3. plot a calibration curve of absorbance v conc
4. start reaction in the sample cell of the colorimeter, measure absorbance rate continuosly
5. use calibation curve to turn absorbance readings into conc readings

Question 7

What is the definition of the rate equation?

Answer 7

the rate equation for a reaction shows how the rate depends on the concentrations of reactants

Question 8

What is the generic rate equation?

Answer 8

Rate = K[A]^m [B]^n

Question 9

What is K in the rate equation?

Answer 9

the rate constant

Question 10

What is m/n in the generic rate equation?

Answer 10

the order of reaction with respect to the reactant

Question 11

How do you calculate the overall order of reaction (generic)?

Answer 11

m + n
the sum of the separate orders

Question 12

What is the definition of the rate constant?

Answer 12

a measure of the probability that a reaction will happen when the particles collide

Question 13

What happens to K as the temp increases? and why?

Answer 13

K increases as the temp increases
because the proportion of reactant molecules (or ions) with energy greater than the activation energy increases

Question 14

How does concentration and pressure affect K?

Answer 14

it doesnt have any affect on K

Question 15

What is half life?

Answer 15

the time taken for the concentration of a reactant to fall to half its original value

Question 16

What is the abbreviation for half life?

Answer 16

t 1/2

Question 17

What is the rate equation for 0 order?

Answer 17

rate = K

Question 18

What happens to the t1/2 of a 0 order reaction?

Answer 18

sucessive half-lives decrease

Question 19

What are the units for K for 0 order?

Answer 19

the same as rate - moldm-3 s-1

Question 20

What is the rate equation for a first order reaction?

Answer 20

Rate = K[A]

Question 21

What happens to the t1/2 of a 1st order reaction?

Answer 21

successive half-lives remain constant

Question 22

How can you calculate the value of K from the t1/2 (t1/2 equation)?

Answer 22

K = ln 2 / t1/2

Question 23

What is the relationship between the [A] and the rate of a 1st order reaction?

Answer 23

they are directly proportional

Question 24

How would you find the value of K from a 1st order rate v conc graph?

Answer 24

the gradient = K

Question 25

What is the rate equation of a 2nd order reaction?

Answer 25

rate = K[A]^2

Question 26

What happens to the t1/2 in a 2nd order reaction?

Answer 26

successive half-lives increase

Question 27

What is the units of k for a 1st order reaction?

Answer 27

s-1

Question 28

What are the units of K in a 2nd order reaction?

Answer 28

mol-1 dm3 s-1