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(denoted t1/2), is expressed as follows: Co
for n 0,
2k
ln 2 for n 1,
k t1 / 2 t1 / 2 t1 / 2 1
Co k for n 2. In general, the halflife is proportional to (C0)1n. We will use these relations to determine
the order of the reaction in Part I. Because the rate constant can be readily calculated
from t1/2 as shown above (they are inversely proportional), a determination of t1/2 will
yield the rate constant.
Question A: What would you expect for the ratio of the halflives, t1/2 (0.05 M) / t1/2
(0.01 M), if the reaction were (a) zero order, (b) first order, or (c) second order? The last part of the assignment is the determination of the activation energy of the
reaction. The rate constant for a reaction is related to the energy of activation, Ea, by the
Arrhenius equation:
k = AeEa/RT
where A is a constant characteristic of the reaction, R is the gas constant, and T is the
absolute temperature in Kelvin. By taking the logarithm of both sides, we obtain:
ln k Ea 1 ln A
R T Thus, if you determine the rate constant f...
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This note was uploaded on 04/09/2013 for the course CHE CHE 2C taught by Professor Nasiri during the Spring '07 term at UC Davis.
 Spring '07
 Nasiri
 Chemistry

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