Reactions with known invariant stoichiometry

The concentration-time data from a reaction whose stoichiometry has been studied independently of its rate and found to be invariant can be analysed much more rigorously than the data from a reaction whose stoichiometry is unknown. Every effort should be made to avoid this latter situation since the advantages of a knowledge of the stoichiometry more than compensate for the time spent in obtaining the additional experimental observations which are required. Nowhere is this more obvious than when the stoichiometry is known and invariant so that the reaction can be written 

Since most reactions are studied under conditions where the volume remains constant or almost so, we shall coniine the remainder of the discussion of this chapter to these cases. 

In order to rigorously test the data for consistency with the rate expression 

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