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Equation 5 · Part 2 · Chemical Dynamics and Catalysis in Practice: An Advanced Technical Guide

subscript

KiK_i
subscript

What this part means

The lower label selects a particular version, component, or indexed member of the quantity. For example, x₀ and xₜ can be values at different positions.

Its job in the formula

A subscript distinguishes a version, component, step, or member of a quantity. It does not automatically mean multiplication.

The passage around this formula

Here r is the overall reaction rate, kik_i is the rate constant of step i , and the partial derivative is taken holding the equilibrium constant KiK_i of that step fixed (so that only kinetics, not thermodynamics, is perturbed) and all other rate constants constant. This equation matters because it is the formal object the rest of this section’s isotope analysis is trying to estimate indirectly — DRC values are rarely measured directly; they are inferred from how observables like isotope ratios and apparent activation energies respond to controlled perturbations.

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Learn the underlying idea

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

Open the illustrated subscripts: which member of a family? guide →

Sources cited in the article section

These citations provide research context; check each source for the exact claim it supports.