chemical analysis

• What is the purpose of chemical analysis?

  To identify and quantify substances
• What happens when a glowing splint is placed in a gas?

  It reignites if oxygen is present
• What is the boiling point of pure water?

  100°C
• What is the freezing point of pure water?

  0°C
• What color does copper(II) sulfate turn when water is present?

  Blue
• What are the steps for testing for hydroxide precipitations?


  1. Add sodium hydroxide solution
  2. Note the color of the precipitate
  3. Observe if it dissolves in excess NaOH
• How can you differentiate between aluminum, magnesium, and calcium ions?

  By their precipitate behavior in NaOH
• What is the order of tests for anions to avoid false positives?

  1. Test for carbonates
  2. Test for sulfates
  3. Test for halides
• What is the purpose of paper chromatography?

  • To separate mixtures
  • To identify components like dyes in ink
  • To analyze components of blood
• What are the two phases in paper chromatography?

  Mobile phase (solvent) and stationary phase (paper)
• How is the R value calculated in chromatography?

  R = distance of component / distance of solvent
• What does an R value of 1 indicate?

  Very soluble component
• What does an R value of 0 indicate?

  Insoluble component
• What are the differences between quantitative and qualitative tests in chemistry?

  • Quantitative: Measures how much substance is present
  • Qualitative: Identifies unknown substances
• What are the advantages of instrumental analysis?

  • Rapid analysis
  • Improved accuracy
  • High sensitivity
• What are the disadvantages of instrumental analysis?

  • High costs
  • Requires training
  • Time-consuming
• How does flame emission spectroscopy work?

  It analyzes light emitted by heated metal ions
• What is the purpose of gas chromatography?

  To separate and analyze gaseous mixtures
• What is the role of a spectrometer in flame emission spectroscopy?

  To analyze the wavelength of emitted light
• What is the significance of the retention factor (R value) in chromatography?

  • Indicates solubility of components
  • Helps identify substances in mixtures
• Explain how paper chromatography separates substances (3 marks)

  • Solvent moves through paper
  • Carries substances different distances
  • Depend on their attraction to the solvent and paper