## Activation Energy

For users of the Mathcad browser: wmc-re1.mcd (8 KB, ver. 5.0)The rate constant is a function of
the temperature and can be calculated from the *Arrhenius*
equation:

The same
formula can be used to calculate the activation energy *Ea* from a
set of experimentally determined rate constants at different
temperatures.

For example, in the hydrolysis of
2-chloro-2-methylpropane, the following data was obtained:
*T*/K | 303 |
298 | 293 | 288 | 283 |

*k**10^2 | 9.41 | 3.59 | 3.08 | 2.44 |
1.82 |

The exponential
equations can be converted to the linear form by taking the logarithm of
both sides, which in our case would give: Plotting ln*k* against 1/*T* should give an
approximately straight line relationship
with a slope, *Ea/R *and an intercept, ln*A*. In this case
the calculations involve the ln*k* values instead of the plain
*k* values, and the reciprocal values of the temperature.

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