C12

• What happens to metals when heated in a flame?

  They emit distinctive coloured light
• Why do metals emit light when heated?

  Electrons absorb and emit energy from the flame
• What are the flame test colors for lithium, sodium, potassium, calcium, and copper?

  • Lithium: Red
  • Sodium: Yellow
  • Potassium: Lilac
  • Calcium: Orange-red
  • Copper: Green
• What is a precipitate in the context of metal ions?

  An insoluble solid formed in a reaction
• What happens when sodium hydroxide is added to calcium chloride?

  Calcium hydroxide precipitate forms
• What is the precipitate formed by calcium ions?

  Calcium hydroxide: Ca(OH)₂
• What color is the precipitate formed by aluminium ions?

  White
• What color is the precipitate formed by magnesium ions?

  White
• What color is the precipitate formed by copper(II) ions?

  Blue
• What color is the precipitate formed by iron(II) ions?

  Green
• What color is the precipitate formed by iron(III) ions?

  Brown
• How can you differentiate between aluminium, calcium, and magnesium precipitates?

  Add more sodium hydroxide to the solution
• What indicates that the precipitate is aluminium when more sodium hydroxide is added?

  The white precipitate re-dissolves
• What indicates that the precipitate is calcium or magnesium when more sodium hydroxide is added?

  The white precipitate does not re-dissolve
• What flame color indicates the presence of calcium ions?

  Orange-red flame
• What flame color indicates the presence of magnesium ions?

  No color change in flame
• What are the steps to identify metal ions using flame tests and precipitate tests?

  1. Perform a flame test for color.
  2. Add sodium hydroxide to form precipitates.
  3. Observe precipitate behavior with additional sodium hydroxide.
  4. Identify based on flame color and precipitate characteristics.
• What are carbonates composed of?

  Carbon and oxygen
• What happens when an acid is added to a carbonate?

  The carbonate starts to fizz
• What gas is produced when an acid reacts with a carbonate?

  Carbon dioxide
• What is the reaction between calcium carbonate and hydrochloric acid?

  CaCO$_3(s)$ + HCl$(aq)$ → CaCl$_2(aq)$ + CO$_2(g)$ + H$_2$O$(l)$
• What is the first step in testing for halide ions?

  Add dilute nitric acid
• What is the purpose of adding silver nitrate in halide ion testing?

  To form a precipitate with halides
• What precipitate forms when chloride ions are present?

  Silver chloride (white)
• What precipitate forms when bromide ions are present?

  Silver bromide (pale yellow, cream)
• What precipitate forms when iodide ions are present?

  Silver iodide (yellow)
• What is the first step in testing for sulfate ions?

  Add dilute hydrochloric acid
• What is the purpose of adding barium chloride in sulfate ion testing?

  To form a precipitate with sulfate
• What precipitate forms when sulfate ions are present?

  Barium sulfate (white)
• What is the ionic equation for the sulfate test?

  Ba$^{2+}$ + SO$_4^{2-}$ → BaSO$_4(s)$
• What are the steps for testing halide ions?

  1. Add dilute nitric acid to the solution.
  2. Add silver nitrate.
  3. Observe the precipitate color:

  • Chloride: white
  • Bromide: pale yellow, cream
  • Iodide: yellow
• What are the steps for testing sulfate ions?

  1. Add dilute hydrochloric acid to the solution.
  2. Add barium chloride.
  3. Observe the precipitate:

  • If present: barium sulfate (white)