Experimental kinetic data of heterogeneous reactions

The experimental kinetic data of heterogeneous reactions exhibit three aspects  

Note 6.1.- In heterogeneous reactions that involve pure solids in their phase, it is not necessary to study the influence of sohd concentration because this is a constant (ratio of molar mass to molar volume) that cannot be changed from one experiment to another. This does not mean that the amount of the solid phase has no influence on the speed and does not need to be studied, but rather that this quantity should not be confused with a concentration. 

It is very important to know the influence of time during a heterogeneous catalytic reaction. This type of reaction is often assayed in an open circuit with respect to gas, under gas flux. Either time has no influence on speed or there is a decrease in the speed of reaction. The physico-chemical conditions remain constant during the experiment and we talk about the catalyst aging, which is due to several causes (see section 7.4.5). 

When it is possible to compare the kinetics of a reaction both with and without a catalyst - which means that each reaction takes place at a suitable speed that can be measured under the same conditions of temperature and partial pressures by giving the same final products - different speed-concentration relationships and different temperature coefficients are obtained in both measuring conditions, proving the influence of the presence of the catalyst. 

In the presence of a catalyst, different types of speed-partial pressure relationships are obtained. In order to examine them, we consider two types of reactions to one or more reagents. 

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