Mendeleev · science lesson
pH: a logarithmic scale
pH is related to hydrogen-ion activity and uses a logarithmic scale.
Start with the idea
pH is related to hydrogen-ion activity and uses a logarithmic scale.
A concrete example
A one-unit pH difference corresponds to a factor of ten in the associated logarithmic quantity, not a small linear difference.
Practical method
Go one step deeper
At 25 °C, an idealized dilute solution at pH 3 has hydrogen activity about ten times that of one at pH 4.
Common trap
A trend or model is not an exceptionless law. Always check the quantity’s definition and the conditions being compared.
Check your understanding
Can you explain the phenomenon in your own words before looking at an equation?