The key idea
pH is a logarithmic way of expressing hydrogen-ion activity; introductory calculations often approximate activity using concentration in sufficiently dilute solutions.
Why it matters
Because the scale is logarithmic, a change of one pH unit corresponds to a tenfold change in the relevant hydrogen-ion activity ratio.
A picture to remember
Start with the central idea, then test it against a concrete element or example. A scientific model is useful when we know what it explains — and where its limits are.
pH, acids and bases
pH is a logarithmic way of expressing hydrogen-ion activity; introductory calculations often approximate activity using concentration in sufficiently dilute solutions.
The key idea
pH is a logarithmic way of expressing hydrogen-ion activity; introductory calculations often approximate activity using concentration in sufficiently dilute solutions.
Because the scale is logarithmic, a change of one pH unit corresponds to a tenfold change in the relevant hydrogen-ion activity ratio.