Question

When comparing two reactions that are run at different temperatures, why is the transformation that is performed at a lower temperature less likely to yield side products? Please explain.

Answer 1

From the Arhenius equation

K= Ko e^{- Ea/RT}

Ea= Activation energy and K = rate constant

for a given reaction, since activation energy is fixed, Higher the temperature lower the value of Ea/RT and higher the value of K. So the reaction is expected to proceed rapidly and it may also lead to undesirable side products. For example during combustion in presence of atmospheric air at high temperatures , there is a tendency of Nox formation along with CO2.

If temperature is limited, the k value is low and it can prevent the formation of NOx and this is the principle that is used in fluidized bed combustion.