2hChemical tests

Syllabus objectives

• 2.44describe tests for these gases: • hydrogen • oxygen • carbon dioxide • ammonia • chlorine.
• 2.45describe how to carry out a flame test
• 2.46know the colours formed in flame tests for these cations: • Li+ is red • Na+ is yellow • K+ is lilac • Ca2+ is orange-red • Cu2+ is blue-green.
• 2.47describe tests for these cations: • NH4+ using sodium hydroxide solution and identifying the gas evolved • Cu2+, Fe2+ and Fe3+ using sodium hydroxide solution.
• 2.48describe tests for these anions: • Cl–, Br– and I– using acidified silver nitrate solution • SO42– using acidified barium chloride solution • CO32– using hydrochloric acid and identifying the gas evolved.
• 2.49describe a test for the presence of water using anhydrous copper(II) sulfate
• 2.50describe a physical test to show whether a sample of water is pure