Experimental techniques and chemical analysis

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Sample objectives

What this unit covers

• Experimental design: Identify suitable equipment for measuring 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: Explain the following terms: (a) a solvent is a substance that dissolves a solute (b) a solute is a substance that gets dissolved in a solvent (c) a solution is a mixture of one or more solutes dissolved in a solvent (d) a saturated solution is one that has the highest concentration of a solute that can dissolve in the solvent at a given temperature (e) residue is the solid that remains after processes like evaporation, distillation, or filtration (f) filtrate is the liquid or solution that has gone through a filter
• 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 techniques for separating and purifying substances, including: (a) using an appropriate solvent (b) filtration (c) crystallisation (d) simple distillation (e) fractional distillation
• Separation and purification: Propose appropriate methods for separation and purification based on the characteristics of the substances provided
• Identification of ions and gases: Explain the procedures for testing to identify the following anions: (a) carbonate (CO₃²⁻) by reacting with dilute acid and checking for carbon dioxide gas, (b) chloride (Cl⁻), bromide (Br⁻), and iodide (I⁻) by acidifying with dilute nitric acid followed by adding aqueous silver nitrate, and (c) sulfate (SO₄²⁻) by acidifying with dilute nitric acid and then adding aqueous barium nitrate.
• Identification of ions and gases: Outline the tests using aqueous sodium hydroxide and aqueous ammonia to identify the following cations: (a) ammonium (NH₄⁺), (b) calcium (Ca²⁺), (c) copper(II) (Cu²⁺), (d) iron(III) (Fe³⁺), (e) iron(II) (Fe²⁺), and (f) zinc (Zn²⁺). Note that the formulas of complex ions are not necessary.