AQA GCSE Chemistry Required Practical Exam-Style Flashcards: Making Salts

These flashcards cover key concepts and procedures for the Making Salts practical in AQA GCSE Chemistry.

Making Salts

To prepare a pure, dry sample of a soluble salt from an acid and an insoluble base (or carbonate).

Example of Salt Preparation

Making copper(II) sulfate from sulfuric acid and copper(II) oxide.

Word Equation for the Reaction

Sulfuric acid + Copper oxide → Copper sulfate + Water.

Balanced Symbol Equation

H₂SO₄ + CuO → CuSO₄ + H₂O.

Addition of Excess Base

Add excess copper oxide to the warm acid to ensure all the acid reacts.

Heating the Acid

To speed up the reaction between the acid and base without boiling.

Completion of Reaction

When the excess solid stops disappearing, some remains unreacted.

Handling Excess Solid

Filter it out to remove unreacted base.

Obtaining Crystals of the Salt

Evaporate some water to concentrate the solution, then leave to crystallise.

Making Crystals Pure and Dry

Pat dry gently with filter paper.

Excess of the Base

To ensure all the acid reacts and no acid remains in the final solution.

Filtering the Solution

To remove any unreacted solid base.

Reactive Metals Exclusion

They can react too vigorously with acid, causing safety risks.

Heating the Acid Caution

It could spatter or boil, creating safety hazards.

Type of Reaction

Neutralisation — acid + base → salt + water.

Safety Precautions

Wear goggles, handle acids carefully, avoid skin contact, and use tongs for hot equipment.

Overheating the Solution Effect

It may spatter or decompose, producing an impure product.

Final Product Appearance

Blue crystals of copper(II) sulfate (if using copper oxide and sulfuric acid).

Type of Salt from Different Acids

Hydrochloric acid → chloride salts; Sulfuric acid → sulfate salts; Nitric acid → nitrate salts.

Checking the Purity of Crystals

Measure melting point — a pure substance has a sharp melting point.