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Equation 3 · Part 1 · How Chemical Dynamics and Catalysis Actually Work

Symbol S_F

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

What this part means

SFS_F is part of the quantity the equation computes from the expression on the right.

Its job in the formula

SFS_F is part of the quantity the equation computes from the expression on the right.

The passage around this formula

…it with no vocabulary 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…

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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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