B.2.5—Logarithmic quantities

Use logarithms for quantities spanning several orders of magnitude, including pH and pKa calculations.

Use b.2.5—logarithmic quantities to connect the rule to the data and decision in the question.

This matters because b.2.5—logarithmic quantities determines what can be inferred or chosen; begin with the stated conditions and keep the conclusion tied to the evidence.

Example: apply b.2.5—logarithmic quantities to one small, clearly defined case, show the key step or comparison, and explain the result in words.

Boundary: B.2.5—Logarithmic quantities is not a universal recommendation. Check the syllabus scope, assumptions, units and the limits of the evidence before generalising.