Reactivity and rate of an elementary step

From relations [1.11] and [1.19] we deduce the following relation for a reaction 

The reactivity ( ) (or chemical flux according to Lafitte and Rouquerol) of an elementary step is its specific speed. Therefore by using equation [3.1], we obtain the following fundamental relationship  

The rate of an elementary reaction (with a single zone) is the product of its reactivity by its space function. This relation is always tme, whether we are dealing with a volitme zone or a strrface zone. 

In the general case, both properties and E are functions of different parameters affecting the speed (temperature, concerrtrations, partial presstrres, presstrre, the zone s sizes, amounts of substatKes, etc.) arrdfiactiorral exterrt, artd thrrs time. 

1 We do not retain this term because, as discussed in section 3.7.4, it can be confused with the 

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