Making Soluble Salts Using an Acid

Overview

• The process of making a soluble salt using an acid is a required practical in many science exams.
• Example salt: Copper sulfate (CuSO₄).
• Important for exams, likely to be questioned.

Understanding Salts

• Definition: Salts contain a positive metal ion.
• Copper Sulfate:
  • Positive ion: Cu²⁺ (from the metal copper).
  • Negative ion: SO₄²⁻ (from sulfuric acid).

Sources of Metal Ions

1. Metal itself (e.g., copper).
2. Metal oxide (e.g., copper oxide).
3. Metal hydroxide (e.g., copper hydroxide).
4. Metal carbonate (e.g., copper carbonate).

Making Copper Sulfate - Practical Steps

Initial Setup

• Use a fixed amount of dilute sulfuric acid (limiting reactant).
• Important: Ensure all acid reacts to avoid contamination.

Heating the Acid

• Gently heat until almost boiling (do not boil to prevent bubbling over).
• Add copper oxide gradually with a spatula.
• Stir with a glass rod.
• Solution turns blue (indicates copper sulfate formation).

Reaction Completion

• Continue adding copper oxide until solution remains blue.
• Stop adding if powder remains - indicates reaction completion.

Filtration

• Filter to remove unreacted copper oxide using filter funnel and paper.

Crystallization

• Heat solution in an evaporating basin over boiling water until half remains.
• Leave in a cool place for 24 hours for crystals to form.
• Scrape crystals onto a paper towel and pat dry.

Final Product

• Obtain pure, dry crystals of copper sulfate.

Additional Resources

• Vision workbook: Contains more questions on this practical.
• Useful for exam preparation.

Key Points to Remember

• Follow steps carefully to ensure purity of the salt.
• Understand the role of each component and step in the process.
• Familiarity with practical will aid exam performance.