pH, Neutralisation, Titration and Salts
Relate pH to hydrogen and hydroxide ions, write neutralisation equations, identify spectator ions, calculate titration quantities and choose a soluble-salt preparation.
How to study National 5 Chemistry
Move between particle explanations, formulae, calculations, experimental evidence and justified conclusions, while using official materials for exact written-paper and assignment practice.
Core concepts
Concept 1
Acidic solutions contain more H⁺(aq) than OH⁻(aq), alkaline solutions contain more OH⁻(aq), and dilution moves pH towards 7.
Exam cue: Use the acid and base identities to predict products before writing an equation.
Concept 2
Bases neutralise acids to form water and a salt; the acid controls whether the salt is a chloride, sulfate or nitrate.
Exam cue: Remove only ions that are unchanged on both sides when forming an ionic equation.
Concept 3
Titration measures reacting solution volumes accurately, while an insoluble excess base followed by filtration is an alternative route to a soluble salt.
Exam cue: For a pure salt from titration, repeat the measured volumes without indicator before evaporation.
Risk pitfalls and guardrails
Assuming every base dissolves in water and is therefore an alkali.
Guardrail: Check formulae, charges, units, state or experimental conditions before committing to the final conclusion.
Naming the salt from the metal only and ignoring the acid.
Guardrail: Check formulae, charges, units, state or experimental conditions before committing to the final conclusion.
Leaving indicator in the solution used to prepare a pure salt.
Guardrail: Check formulae, charges, units, state or experimental conditions before committing to the final conclusion.
Memory anchors
Acidic solution
An acidic solution has more H⁺(aq) than OH⁻(aq) and a pH below 7.
Alkaline solution
An alkaline solution has more OH⁻(aq) than H⁺(aq) and a pH above 7.
Neutralisation
A base reacts with an acid to form water and a salt.
Spectator ion
A spectator ion remains chemically unchanged during the reaction.
Titration end-point
An indicator shows when accurately measured reacting volumes have reached the end-point.
Excess-base salt method
Add excess insoluble base, filter off the excess, then evaporate the filtrate.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
Which ion is present at a higher concentration in an acidic solution?
Solution P has pH 11. Which comparison explains why it is alkaline?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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