c4.2

• Identifying the products of chemical reactions

  1. Describe tests to identify selected gases

  2. Describe tests to identify aqueous cations and aqueous anions

  3. Describe how to perform a flame test

  4. Identify species from test results

  5. Interpret flame tests to identify metal ions

  6. Describe the advantages of instrumental methods of analysis

  7. Interpret an instrumental result given appropriate data in chart or tabular form, when accompanied by a reference set of data in the same form
• Carbon dioxide test


  Bubble the gas through limewater (carbon hydroxide) and it will turn milky (cloudy)
• Chlorine test


  When damp litmus paper is put into chlorine gas the litmus paper is bleached and turns white
• Hydrogen test


  Use a burning splint held at the open end of a test tube of the gas, creates a 'squeaky pop' sound
• Oxygen test


  Uses a glowing splint inserted into a test tube of the gas, splint relights in oxygen
• Carbonate test


  Carbonates react with dilute acids to create carbon dioxide, this gas can be bubbled through limewater, if the limewater goes cloudy, the gas is CO2
• Halide test


  First add dilute nitric acid, followed by silver nitrate solution. Chloride gives a white precipitate, bromide gives a cream precipitate, iodide gives a yellow precipitate
• Sulfate test


  First add dilute hydrochloric acid, followed by barium chloride solution. A white precipitate will form when sulfate ions are in this solution
• Flame test


  Take a sample of the metal and hold on a spatula in a flame from a Bunsen burner and witness the colour that the flame turns dependent on the metal being tested
• Flame test colours


  • Lithium - Crimson
  • Sodium - Yellow
  • Potassium - Lilac
  • Copper(II) - Green
  • Calcium - Orange-red
• Instrumental methods of analysis

  • Elements and compounds can be detected and identified using them
  • They are accurate, sensitive and rapid
• Instrumental results can be interpreted using appropriate data in chart or tabular form, when accompanied by a reference set of data in the same form