Chemical kinetics lecture

Question 1

What are rate of reactions?

Answer 1

How to measure rates

Question 2

What is rate laws?

Answer 2

How to calculate amount left or time to reach a given amount

Question 3

What is stability and half life?

Answer 3

How long it takes to react 50% of reactants

Question 4

What is arrhenius equation?

Answer 4

How rate constant changes with T

Question 5

What is acid and base catalysis?

Answer 5

Mechanism of catalysis

Question 6

How does kinetics play into pharmaceutical systems?

Answer 6

Rate of drug degradation needs to be known
Understanding stability characteristics to handle and store products
Effects of temperature, light, and catalysts on the stability of drug formulation
Possible breakdowns
More stable drug preparations

Question 7

Knowledge of deterioration at various hydrogen ion concentrations allows what?

Answer 7

One to choose a vehicle that will retard or prevent degradation

Question 8

What is thermodynamics?

Answer 8

Does a reaction take place?

Question 9

What is kinetics?

Answer 9

How fast does a reaction proceed?

Question 10

Define reaction rate

Answer 10

Change in the concentration of a reactant or a product with time (dc/dt)
dc = increase or decrease of concentration over an infinitesimal time interval, dt

Question 11

The rate of a chemical reaction is proportional to the product of the ??

Answer 11

molar concentration of the reactants each raised to a power usually equal to the number of molecules, a and b, of the substances A and B undergoing reaciton

Question 12

Define rate law

Answer 12

Relationship of the rate of a reaction to the rate constant and the concentration of the reactants raised to some power

Question 13

What is the specific rate constant for a reaction?

Answer 13

The constant k appearing in the rate law associated with a single-step reaction

Question 14

Define pseudo-order

Answer 14

One of the reactants is present in such a great excess that its concentration may be considered constant or nearly so
- Depends on only the first power

Question 15

What is a zero-order reaction?

Answer 15

The decomposition proceeds at a constant rate and is independent of the concentration of any of the reactants

Question 16

Define half-life

Answer 16

Time required for one half of the material to disappear; it is the time at which A has decreased to 1/2A

Question 17

Zero- reaction graph ?

Answer 17

Linear equation plotted with [A] on the y axis and t on the x and the slope is equivalent to k

Question 18

First-order reaction graph?

Answer 18

y axis = lnA

Question 19

Second-order reaction graph?

Answer 19

y axis = 1/[A]

Question 20

Define second-order

Answer 20

When A and B are present in the same concentration, the integrated form of the second order reaction

Question 21

Define the substitution method

Answer 21

Data accumulated in a kinetic study may be substituted in the integrated form of the equations that describe the various orders
The equation is found in which the calculated k values remain constant within the limits of experimental variation, the reaction is considered to be of that order

Question 22

What factors affecting reaction rate?

Answer 22

Concentration of reactants: Increase so does the likelihood that reactant molecules will collide
Temp: higher, more kinetic energy, move faster, and collide more
Catalysts: speed reaction by changing mechanism
Solvent
Light

Question 23

What is Arrhenius equation?

Answer 23

k= Ae-(Ea/RT)
lnk= lnA- (Ea/R*1/T)
1/T against log k

Question 24

Define activation energy

Answer 24

Energy barrier (hump) that must be overcome for a chemical reaction to proceed

Question 25

Define shelf-life

Answer 25

Length of storage time before the preparation becomes unfit for use with regard to strength, through either chemical decomposition or physical deterioration
- No more than 10%l provided the decomposition product are not more toxic or harmful than the original

Question 26

Define catalyst

Answer 26

A substance that influences the speed of a reaction without itself being altered chemically