C4.2 Identifying the products of chemical reactions

• What is the focus of section C4.2 in the study material?

  Identifying the products of chemical reactions
• What is the first topic covered under C4.2.1?

  Detecting gases
• What gas is specifically mentioned for detection in the study material?

  Carbon dioxide
• How can chlorine be detected according to the study material?

  Using a piece of damp litmus paper
• What is the purpose of using damp litmus paper in gas detection?

  To observe a color change indicating the presence of chlorine
• What is the second topic covered under C4.2.2?

  Detecting cations
• What is a flame test used for?

  To identify the presence of certain metal ions based on flame color
• How do you perform a flame test?

  By dipping a loop into a solution and holding it in a flame
• What should you do after performing a flame test?

  Record the color of the flame
• Why is it important to clean the loop between tests?

  To avoid contamination and ensure accurate results
• What are the two ways to detect cations mentioned in the study material?

  Using flame tests and hydroxide precipitate tests
• What is the purpose of hydroxide precipitate tests?

  To identify metal ions based on the formation of colored precipitates
• What is the focus of section C4.2.3?

  Detecting anions
• How do you detect halide ions?

  By adding silver nitrate solution to the sample
• How do you detect sulfate ions?

  By adding dilute hydrochloric acid followed by barium chloride solution
• What happens when you add barium chloride to a solution containing sulfate ions?

  A white precipitate of barium sulfate forms
• What is the method to detect carbonate ions?

  By adding dilute hydrochloric acid and observing for bubbles of gas
• What gas is produced when carbonate ions react with hydrochloric acid?

  Carbon dioxide
• What is the balanced equation for the reaction between magnesium carbonate and hydrochloric acid?

  MgCO₃ + 2HCl → MgCl₂ + H₂O + CO₂
• What is the focus of section C4.2.4?

  Instrumental methods of analysis
• What are instrumental methods of analysis?

  Methods that rely on machines to analyze substances
• What are some advantages of instrumental methods of analysis?

  They are sensitive, accurate, and fast
• Why are instrumental methods useful for analyzing complex mixtures?

  They can separate and identify multiple components simultaneously
• What is the purpose of mass spectrometry?

  To determine the mass-to-charge ratio of ions
• How can mass spectra be interpreted?

  By analyzing the peaks to determine the molecular weight of compounds
• What does the height of a peak in a mass spectrum indicate?

  The relative abundance of that ion in the sample
• What is the significance of the molecular ion peak in mass spectrometry?

  It corresponds to the molecular weight of the compound
• How can chromatograms be used in analysis?

  To separate and identify components of a mixture
• What is the relationship between the retention time in chromatography and the properties of the substances?

  Substances with lower affinity for the stationary phase have longer retention times
• What is the role of a solvent in chromatography?


  To carry the sample through the stationary phase
• Why is it important to calibrate instruments used in analysis?

  To ensure accurate and reliable results
• How can the results from mass spectrometry and chromatography be combined?

  To confirm the identity of a compound by comparing retention times and mass spectra