Chemistry · Grades 11–12
Buffers and acid–base ratios · Revision sheet
Use a buffer approximation only where its assumptions fit.
Learn the idea
Buffer
A common buffer contains a weak acid and its conjugate base in appreciable amounts.
Role
A buffer resists small additions of acid or base; its capacity is finite.
Approximation
pH ≈ pKa + log₁₀([A⁻]/[HA]) in the appropriate dilute equilibrium approximation.
Limits
Large additions that consume a component require stoichiometric accounting before any buffer approximation.
Explain without looking
- Diluting an ideal buffer keeps its acid/base ratio nearly unchanged. What can still decrease?
- Why is the Henderson–Hasselbalch relationship an approximation when concentrations replace activities?
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.