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Example Questions
Example Question #3 : Kinetics
The overall reaction can only proceed as quickly as the __________.
intermediate is decomposed
catalyst is added
products are removed
rate-determining step
rate-determining step
The rate-determining step in a reaction mechanism is a kinetic bottleneck, in that it prevents the overall reaction from proceeding; thus, it is what determines how quickly the overall reaction can proceed.
Example Question #1 : Principles Of Reaction Kinetics
Which of the following does not affect a forward reaction rate?
Medium
Temperature
Product concentration
Catalysts
Product concentration
Product concentration would not affect a forward reaction rate, since that is what is being formed. Catalysts specifically speed up reaction rates, as does temperature. Medium can also affect reaction rate because some molecules are more likely to react with each other in certain environments.
Example Question #2 : Principles Of Reaction Kinetics
Which of the following is not true of the transition state?
It cannot dissociate into products without needing any additional energy
It has a greater energy than the products
Old bonds are weakened and new bonds begin to form
It has a greater energy than the reactants
It cannot dissociate into products without needing any additional energy
The transition state is the energy barrier in a reaction—energy is needed to reach this state. Once it is acheived, however, it can either revert back to reactants or dissociate into products without any added energy.
Example Question #101 : Thermochemistry And Kinetics
Which of the following is true:
I. First order reactions proceed at a constant rate
II. First order reactions have a constant half-life
III. First order reactions have one reactant
I only
II only
I, II, and III
II and III
II only
First order reactions have the rate equation 
The half-life equation is 
Lastly, the overall reaction can have any number of reactants. A reaction is first order because its rate-limiting step has only one reactant.
Only statement II is true.
Example Question #102 : Thermochemistry And Kinetics
The following reversible reaction takes place in a closed container:
The system is allowed to reach equilibrium before 2 moles of reactant A are added to the container.
The net rate of formation of product B immediately following the addition of reactant A is __________.
zero
impossible to determine without additional information
positive
negative
positive
According to Le Chatelier's principle, an increase in the concentration of reactants will cause the reaction to shift to the right in order to re-establish equilibrium. Thus, immediately after reactant A is added, the forward reaction will increase and the net rate of formation of the products will be positive.
Example Question #103 : Thermochemistry And Kinetics
Rate data is collected for a reaction, and the following integrated rate law is derived.
If this reaction is __________ with respect to reactant A, a plot of ln[A] versus time would be __________.
zero order . . . linear
first order . . . linear
first order . . . parabolic
second order . . . parabolic
first order . . . linear
The integrated rate law shown is for a reaction rate law with a first-order dependence on reactact A. If such a rate law accurately describes the kinetics of the reaction, then ln[A] will vary linearly with respect to time.
Example Question #104 : Thermochemistry And Kinetics
Which of the following affects the rate of a reaction?
All of these
Frequency of collision
Collision orientation
Molecules' energies
All of these
Since reactant molecules collide and interact to break old bond and form new ones, any factors affecting collision and interactions will affect the reaction rate. Thus, increasing temperature will increase both the frequency of collisions and the average kinetic energy of the molecules. Enzymes bring molecules close to each other and orient them in a way that facilitates reactions.
Example Question #1 : Composition Of Mixtures
Which of the following mixtures is not a homogeneous mixture:
Oil and vinegar
Tea
Wine
A table salt solution
Coffee
Oil and vinegar
A homogeneous mixture is a uniform mixture of two or more components that appears uniform throughout. The oil and vinegar mixture would not appear uniform, and thus is a heterogeneous mixture.
Example Question #2 : Composition Of Mixtures
Which of the following is a heterogeneous mixture.
All of the above
Oatmeal chocolate chip cookie
Orange juice with no pulp
Motor oil
Gasoline
Oatmeal chocolate chip cookie
A heterogeneous mixture is a mixture of two or more components that do not appears uniform throughout. The oatmeal chocolate chip cookie mixture would not appear uniform, and thus is a heterogeneous mixture.
Example Question #3 : Composition Of Mixtures
Which of the following are mixtures
All of the above
Top soil
Reeses Peanut butter cup
b and c
Distilled water
b and c
A mixture contains two or more different substances. Distilled water only contains liquid water, and is not a mixture.
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