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Equation 3 · Part 4 · How Chemical Dynamics and Catalysis Actually Work

Symbol xi_j

SF=ξi/∑jξjS_F = \xi_i / \sum_j \xi_j
ξj\xi_j

What this part means

xiji_j is an input to the expression that computes the quantity on the left.

Its job in the formula

xiji_j is an input to the expression that computes the quantity on the left.

The passage around this formula

…that presumes anything about the catalyst’s intent: fractional selectivity for a given product is the extent-of-reaction rate toward that product divided by the sum of rates toward all products, SFS_F = ξi\xi_i / ∑j\sum_j ξj\xi_j , and relative selectivity between two products is simply the ratio of their two rates [ 2 ] . Selectivity is therefore a kinetic competition among simultaneous pathways, decided by which transition state a given surface site makes cheapest, not a property the catalyst “prefers.” Engineering…

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A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

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Sources cited in the surrounding passage

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