CHEM 1011 Medical Gen. Chemistry Midterm
Prep Questions with complete solutions
Which of the following affects the activation energy of a
reaction? correct answer: presence of a catalyst
A reaction has an activation energy of 195.0 kJ/mol. When the
temperature is increased from 200.°C to 220.°C, the rate
constant will increase by a factor of correct answer: 7.5
Reaction intermediates differ from activated complexes in that
correct answer: they are molecules with normal bonds rather
than partial bonds and can occasionally be isolated
A transition state is a species (or state) corresponding to an
energy maximum on a reaction energy diagram. correct answer:
True
A boiled egg can be cooked at 100.0 °C in exactly 5 minutes. At
an altitude of around 2000 m where the boiling point of water is
93.0 °C, it takes exactly 7.5 minutes to cook the egg to the same
amount. What is the activation energy for the reaction involved
when an egg is boiled? correct answer: 66 kJ/mol
If the activation energy of a reaction decreases by 10.0 kJ/mol,
from 100.0 to 90.0 kJ/mol, what effect will this have on the rate
of reaction at 298K? correct answer: The rate will increase, by a
factor of more than 50.
, The gas-phase reaction CH3NC à CH3CN has been studied in a
closed vessel, and the rate equation was found to be: Rate = -
[CH3NC]/t = k[CH3NC]. Which one of the following actions is
least likely to cause a change in the rate of the reaction? correct
answer: continuously removing CH3CN as it is formed
A reaction intermediate is a species corresponding to a local
energy maximum on a reaction energy diagram. correct answer:
False
A catalyst lowers the activation energy but does not affect the
mechanism of a reaction. correct answer: False
In a reversible reaction, a catalyst will speed up the forward
reaction but not affect the reverse reaction correct answer: False
Which of the following sets of units could be appropriate for a
zero-order rate constant? correct answer: mol L-1 s-1
The rate constant for the reaction 3A à 4B is 6.00 × 10-3 L mol-
1min-1. How long will it take the concentration of A to drop
from 0.75 M to 0.25 M? correct answer: 440 min
The rate law cannot be predicted from the stoichiometry of a
reaction. correct answer: True
2NH3(g) à N2(g) + 3H2(g), If the rate ∆[H2]/∆t is 0.030 mol L-
1s-1, then ∆[NH3]/∆t is correct answer: -0.020 mol L-1s-1
Ammonium cyanate (NH4CNO) reacts to form urea
(NH2CONH2). At 65°C the rate constant, k, is 3.60 L mol-1s-1.
Prep Questions with complete solutions
Which of the following affects the activation energy of a
reaction? correct answer: presence of a catalyst
A reaction has an activation energy of 195.0 kJ/mol. When the
temperature is increased from 200.°C to 220.°C, the rate
constant will increase by a factor of correct answer: 7.5
Reaction intermediates differ from activated complexes in that
correct answer: they are molecules with normal bonds rather
than partial bonds and can occasionally be isolated
A transition state is a species (or state) corresponding to an
energy maximum on a reaction energy diagram. correct answer:
True
A boiled egg can be cooked at 100.0 °C in exactly 5 minutes. At
an altitude of around 2000 m where the boiling point of water is
93.0 °C, it takes exactly 7.5 minutes to cook the egg to the same
amount. What is the activation energy for the reaction involved
when an egg is boiled? correct answer: 66 kJ/mol
If the activation energy of a reaction decreases by 10.0 kJ/mol,
from 100.0 to 90.0 kJ/mol, what effect will this have on the rate
of reaction at 298K? correct answer: The rate will increase, by a
factor of more than 50.
, The gas-phase reaction CH3NC à CH3CN has been studied in a
closed vessel, and the rate equation was found to be: Rate = -
[CH3NC]/t = k[CH3NC]. Which one of the following actions is
least likely to cause a change in the rate of the reaction? correct
answer: continuously removing CH3CN as it is formed
A reaction intermediate is a species corresponding to a local
energy maximum on a reaction energy diagram. correct answer:
False
A catalyst lowers the activation energy but does not affect the
mechanism of a reaction. correct answer: False
In a reversible reaction, a catalyst will speed up the forward
reaction but not affect the reverse reaction correct answer: False
Which of the following sets of units could be appropriate for a
zero-order rate constant? correct answer: mol L-1 s-1
The rate constant for the reaction 3A à 4B is 6.00 × 10-3 L mol-
1min-1. How long will it take the concentration of A to drop
from 0.75 M to 0.25 M? correct answer: 440 min
The rate law cannot be predicted from the stoichiometry of a
reaction. correct answer: True
2NH3(g) à N2(g) + 3H2(g), If the rate ∆[H2]/∆t is 0.030 mol L-
1s-1, then ∆[NH3]/∆t is correct answer: -0.020 mol L-1s-1
Ammonium cyanate (NH4CNO) reacts to form urea
(NH2CONH2). At 65°C the rate constant, k, is 3.60 L mol-1s-1.
