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Can the exact number of ions in a solution be measured?

This philosophical-practical question arose during a discussion on measurement limits in electrochemistry. We can measure concentration with high accuracy, but the concept of an "exact count" seems to hit a wall of Avogadro-scale numbers and quantum uncertainty. I'm curious about the fundamental and practical limits of our best techniques.

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By Vishal Answered 1 year ago

This gets to the heart of measurement philosophy. From my work with ultratrace analysis, we can never measure an "exact count" in a macroscopic volume. Even with single-molecule detection techniques, you're counting events over time, which is statistical. At the scale of a mole, you're dealing with ~10²³ entities; the uncertainty in defining the solution's boundary alone precludes an exact count. We measure average concentrations with incredible precision (parts-per-trillion), but the "exact number" is a conceptual ideal. We operate on highly accurate statistical estimates, which for all practical purposes, are exact.

   

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