FINISHED_Final_Notebook_Jones

A. C.
B. D.
Explanation: ‘D’ is the answer because, given the information provided on the chart, it can be seen
that the catalyst lowered the required energy for the reaction to activate, and it progressed similarly.
The other graphs do not demonstrate the lowering of the activation energy. In fact, ‘B’ demonstrates
an increase in the required activation energy, and ‘C’ represents a “multistage” reaction, in which
there are intermediate products and where multiple “micro-reactions” occur. This same principle of
multiple reactions is demonstrated in ‘A.’
9. H​2​O​2,​
hydrogen peroxide, naturally breaks down into H​ 2​
O and O​2​
over time. MnO​2​, manganese
dioxide, can be used to lower the energy of activation needed for this reaction to take place and, thus,
increase the rate of reaction. What type of substance is MnO​ 2​
?
A. a catalyst
B. an enhancer
C. an inhibitor
D. a reactant
Explanation: The answer is “a catalyst” because a substance which lowers the activation energy of a
reaction and thus increases the rate of reaction is a catalyst, not an enhancer, inhibitor, or reactant.
An inhibitor accomplishes the opposite effect, interfering with the action of a catalyst. A reactant is
merely a required part of the reaction to form a product, and an “enhancer” has no explicit definition
or purpose in chemical reactions.
10. When a reaction is at equilibrium and more reactant is added, which of the following changes is
the immediate result?
A. The reverse reaction rate remains the same.
B. The forward reaction rate increases.
C. The reverse reaction rate decreases.
D. The forward reaction rate remains the same.
Explanation: When a reaction is at ​equilibrium​, its forward reaction rate and reverse reaction rate
have reached an equal state, where the production of products and reactants have become equal. If
more reactant is added, this increases the forward reaction rate as the reaction attempts to achieve
equilibrium again. This is why ‘B’ is the answer. “The reverse reaction rate decreases” is incorrect,
because, in order for the reaction to achieve equilibrium again after more reactants are added, the
reaction must speed up the forward reaction to use up the excess reactants. “The forward reaction
rate remains the same” is incorrect because of the aforementioned reasoning. “The reverse reaction
rate remains the same” is incorrect, because if the forward reaction rate increases to accommodate
the excess reactants, equilibrium implies the two rates are equal, so there must be a change in the
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