pH: understanding the logarithmic scale
pH is not a linear scale. A difference of one unit corresponds, in the usual approximation, to a tenfold factor in hydrogen-ion activity.
Core idea
pH is not a linear scale. A difference of one unit corresponds, in the usual approximation, to a tenfold factor in hydrogen-ion activity.
A concrete example
Moving from pH 4 to pH 3 does not simply mean 'a little more acidic': the logarithmic scale changes how values must be compared.
Why it matters
This concept connects symbolic scientific language with what actually happens at atomic, molecular or experimental scales. Before applying a formula, always check the quantities, units and assumptions of the model.
Check it yourself
Restate the idea without technical vocabulary, then repeat the reasoning with a simple value. If your explanation and calculation tell different stories, revisit the assumptions.
Moving from pH 4 to pH 3 does not simply mean 'a little more acidic': the logarithmic scale changes how values must be compared.