Experimental techniques and chemical analysis

Topics

Choose a topic to revise

Sample objectives

What this unit covers

• Experimental design: Identify the correct equipment used to measure time, temperature, mass, and volume, which includes: (a) stopwatches (b) thermometers (c) balances (d) burettes (e) volumetric pipettes (f) measuring cylinders (g) gas syringes
• Experimental design: Discuss the pros and cons of different experimental techniques and equipment.
• Acid-base titrations: Explain the process of an acid-base titration, highlighting the roles of a burette, a volumetric pipette, and an appropriate indicator.
• Acid-base titrations: Explain how to determine the end-point of a titration by using an indicator.
• Chromatography: Explain the process of using paper chromatography to separate mixtures of soluble colored substances with an appropriate solvent.
• Chromatography: Analyze simple chromatograms to determine: (a) unknown substances by comparing them with known substances (b) whether substances are pure or impure.
• Separation and purification: Explain and describe various methods for separating and purifying substances, including the use of a suitable solvent, filtration, crystallisation, simple distillation, and fractional distillation.
• Separation and purification: Propose appropriate techniques for separation and purification based on the characteristics of the substances provided.
• Identification of ions and gases: Explain the procedures for testing and identifying the following anions: (a) carbonate (CO₃²⁻) through its reaction with dilute acid and subsequent carbon dioxide gas detection; (b) halides (chloride Cl⁻, bromide Br⁻, iodide I⁻) by acidifying with dilute nitric acid followed by the addition of aqueous silver nitrate; (c) nitrate (NO₃⁻) by reduction with aluminum foil and sodium hydroxide, then testing for ammonia gas; (d) sulfate (SO₄²⁻) by acidifying with dilute nitric acid and adding barium nitrate; (e) sulfite (SO₃²⁻) through reaction with acidified potassium manganate(VII).
• Identification of ions and gases: Outline the tests using aqueous sodium hydroxide and ammonia to identify the following cations: (a) aluminum (Al³⁺), (b) ammonium (NH₄⁺), (c) calcium (Ca²⁺), (d) chromium(III) (Cr³⁺), (e) copper(II) (Cu²⁺), (f) iron(III) (Fe³⁺), (g) iron(II) (Fe²⁺), (h) zinc (Zn²⁺).