Momentaneous and Integral Yield for Parallel Reactions

As a measure of the product distribution, integral (total) and momentaneous yields are often used. Let us assume that component A is consumed by two composite reactions with the following stoichiometry  

In other words, it describes the generated amount of R per A, normalized by the 

The momentaneous yield, 9r/a in contrast, describes the normalized ratio between the production rate of R and the consumption rate of A  

With the aid of molar mass balances, one can prove that the total and momentaneous yields obtain similar expressions for a CSTR. The balances for R and A consequently become 

After dividing the previous balances with each other, we obtain 

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