Chemical kinetics is the area of chemistry
concerned with reaction rates.
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Define reaction rate
A reaction rate is
defined as the increase in the concentration of a
product or the decrease in the concentration of a
reactant, per unit time
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Define instantaneous rate
the average rate during a given time interval
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State the rate law
rate = k[A]^m [B]^n
, where k is the rate constant,
m and n specify the reaction order with respect to
reactants A and B, and m + n is the overall reaction order
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Define the method of initial rates
the method of initial rates which involves
measuring the change in reactant rate as a result of changing the concentration of one reactant.
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State the integrated rate law
The integrated rate law is a concentration–time
equation that lets us calculate concentrations
at any time t or the time required for an initial
concentration to reach any particular value
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Define the zeroth-order reaction
a zeroth-order reaction, the integrated rate law
is [A]t = -kt + [A]0, and a graph of [A] versus time is linear with a slope equal to -k.
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Define the first-order reaction
first-order reaction, the integrated rate law is ln
[A]t = -kt + ln [A]0. A graph of ln [A] versus
time is a straight line with a slope equal to -k
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Define half-life
The half-life (t1/2) of a reaction is the time required for the reactant concentration to drop to one-half its initial value.
9 of 26
State the Arrhenius equation
k = Ae^(-Ea/RT), where A is the frequency factor
and Ea is the activation energy (Ea).
10 of 26
Define the transition state
The configuration of
atoms at the top of the barrier is called the transition state.
11 of 26
State the collision theory
. According to collision theory, the rate
constant is given by k = pZe^(-Ea/RT), where p is a
steric factor (the fraction of collisions in which
the molecules have the proper orientation for
reaction),
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Define a reaction mechanism
A reaction mechanism is the sequence of elementary reactions, or elementary steps, that defines the pathway from reactants to products
13 of 26
State the molecularity rate
The rate law for an elementary reaction follows
directly from its molecularity: rate = k[A] for
a unimolecular reaction, and rate = k[A]^2
or rate = k[A][B] for a bimolecular reaction.
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Define a rate-determining step
The slowest step is called
the rate-determining step
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Define a reaction intermediate
A chemical species
that is formed in one elementary step and consumed in a subsequent step is called a reaction intermediate
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Define a catalyst
A chemical species
that is formed in one elementary step and consumed in a subsequent step is called a reaction intermediate
17 of 26
Define a homogenous catalyst
A homogeneous catalyst is present in the
same phase as the reactants
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Define a heterogenous catalyst
a heterogeneous catalyst is present in a different phase.
19 of 26
Define an enzyme
Enzymes are large protein molecules that act as
catalysts for biological reactions.
20 of 26
State the reaction rate of a reaction formula
a A + b B--->Products
Rate = k[A]^m [B]^n
where k is the rate constant, m is the order of the reaction A, and n is the order of the reaction in B.
21 of 26
State the Integrated rate law and half-life (t1/t2) for a zeroth-order reaction
[A]t = -kt + [A]0 t1/2 = [A]0/2k
where [A]t is the concentration of A at time t and [A]0 is the initial concentration of A.
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State the Integrated rate law and half-life (t1/t2) for a first-order reaction
ln [A]t/[A]0=-kt t1/2 = 0.693/k
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State the Integrated rate law and half-life (t1/t2) for a second-order reaction
1/[A]t= kt +
1/[A]0
t1/2 = 1/k[A]0
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State the rate constant predicted by collision theory: The Arrhenius equation
k = pZe^(-Ea/RT) = Ae^(-Ea/RT)
where p is the steric factor, Z is the collision frequency, Ea is the activation energy, and A (=pZ) is the frequency factor
25 of 26
State the two logarithmic forms of the Arrhenius equation
ln k = ln A - Ea/RT ln(k2/k1)=(-Ea/R)(1/T2-1/T1)
where k1 and k2 are rate constants at temperature T1 and T2
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Other cards in this set
Card 2
Front
Define reaction rate
Back
A reaction rate is
defined as the increase in the concentration of a
product or the decrease in the concentration of a
reactant, per unit time
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