Qualitative Tests

• test for hydrogen molecules: creates a squeaky pop with a lit splint.
• test for oxygen molecules: relights a glowing splint.
• test for chlorine molecules: bleaches damp litmus or universal indicator paper.
• test for hydrogen chloride:

  1. dip glass rod into concentrated ammonia solution.
  2. hold into gas.
  3. white fumes produces.
• test for ammonia:

  1. dip glass rod into concentrated hydrogen chloride solution.
  2. hold into gas.
  3. white fumes produced.
• flame test:

  1. dip nichrome wire into concentrated hydrochloric acid.
  2. dip the wire into the test solid.
  3. hold the wire into the blue bunsen burner flame.
  4. note the colour of the flame.
• flame colour of lithium ions: crimson.
• flame colour of sodium ions: yellow / orange.
• flame colour of potassium ions: lilac / pink through cobalt glass.
• flame colour of calcuim ions: brick-red.
• flame colour of barium ions: apple green.
• flame colour of copper ions: green-blue.
• test for ammonium ions:

  1. warm the solid with a solution of sodium hydroxide.
  2. observe a pungent smell.
  3. dip a glass rod in concentrated hydrogen chloride solution.
  4. hold into gas.
  5. white fumes produced.
• test for sulfate ions:

  1. if supplied with a solid make a solution of the salt (with deionsied water).
  2. add barium chloride solution / barium nitrate solution.
  3. a white precipitate will be formed.
• test for halide ions:

  1. if supplied with a solid make a solution of the salt (in dilute nitric acid).
  2. add silver nitrate solution.
  3. add dilute ammonia solution.
  4. add excess dilute ammonia solution.
  5. if the precipitate remains repeat the process using concentrated ammonia solution.
• positive result for chlorine ions in the test for halide ions: white precipitate, soluble in dilute ammonia solution.
• positive result for bromine ions in the test for halide ions: cream precipitate, soluble in concentrated ammonia solution.
• positive result for iodide ions in the test for halide ions: yellow precipitate, insoluble even in concentrated ammonia solution.
• test for carbonate ions: to the solid add some dilute acid, if there is effervescence, bubble gas produced into limewater to turn it milky.
• test for iodine: add a few drops of starch onto the solution and it will turn blue-black.