5.2 Acid reactions: How can we make and identify salts?
Use pH, neutralisation and acid reactions to prepare pure salts and identify selected ions.
How to study WJEC GCSE The Sciences
Move from a scientific model to a prediction or method, collect or interpret evidence, show quantitative working and finish with a conclusion whose limits match the data.
Core concepts
Concept 1
Relate acidity and alkalinity to hydrogen and hydroxide ions.
Exam cue: Identify the unit, entered tier, supplied reference material, command word and relevant scientific enquiry skill.
Concept 2
Plan salt preparation using the reactants and solubility required.
Exam cue: Choose the preparation route from the required salt, then justify each separation or purification step.
Concept 3
Represent acid reactions and interpret qualitative ion tests.
Exam cue: Use scientific terminology, show quantitative working with units, and connect conclusions to data and the stated model.
Concept 4
Official subtopics: 5.2.1 pH scale; 5.2.2 Neutralisation reactions; 5.2.3 Acid and metals; 5.2.4 Identifying salts.
Concept 5
Scientific enquiry and mathematical skills apply in this topic; bold amplification is Higher Tier only.
Risk pitfalls and guardrails
Using excess soluble alkali in a method intended to produce a pure soluble salt.
Guardrail: Do not import outgoing 3430QD content, another science route, a fixed required-practical list or unsupported tier and connection assumptions.
Recalling a fact without applying it to the observation, data, practical method or unfamiliar context.
Guardrail: Use the live secure pack: Task A may use groups of up to three; Task B is individual and highly controlled. Two enquiries are selected by the centre from three.
Importing content, required practicals, tier rules or paper structure from the outgoing WJEC or another awarding-body route.
Guardrail: Bold amplification is Higher-only. Units 1-6 may mix tiers, but Unit 7 is untiered.
Memory anchors
pH
A scale describing how acidic or alkaline a solution is.
Neutralisation
Reaction in which acid and base form salt and water.
Salt
An ionic compound formed when acid hydrogen is replaced by a metal or ammonium ion.
Precipitate
An insoluble solid formed from solutions.
Indicator
A substance that changes colour according to pH conditions.
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 ions make an aqueous solution acidic? Use ions, solubility and the required salt to select the valid reaction or test. Choose the option that remains valid across the stated range.
Which ions make an aqueous alkali alkaline? Use ions, solubility and the required salt to select the valid reaction or test. Apply the model at the scale described.
Answer all questions to submit.
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Continue learning
Move forward only after this module is stable.
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