C8-Chemical Analysis

• A pure substance contains a single element or compound that is not mixed with any other substance
• An impure substance contains more than one type of element of compound in a mixture
• Pure substances melt and boil at specific temperatures
• A formulation is a mixture that has been designed as a useful product
• Formulations include fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods.
• Testing for chlorine :

  • Use damp litmus paper
  • If chlorine is present, the litmus paper will bleach
• Testing for oxygen ;

  • Use a glowing splint
  • If oxygen is present, the splint will reignite
• Testing for hydrogen :

  • Use a lit splint
  • If hydrogen is present, a squeaky pop will be created
• Testing for carbon dioxide :

  • Use limewater
  • If carbon dioxide is present, the limewater will turn cloudy
• Lithium ions burns with a crimson flame
• Sodium ions burn with a yellow flame
• Potassium ions burn with a lilac flame
• Calcium ions burn with an orange-red flame
• Copper ions burn with a green flame
• Solutions of aluminium, calcium and magnesium ions form white precipitates when sodium hydroxide solution
• Copper(II) forms a blue precipitate when sodium hydroxide solution is added
• Iron(II) a green precipitate when sodium hydroxide solution is added
• Iron(III) forms a brown precipitate when sodium hydroxide solution is added
• Chloride ions form white precipitate when silver nitrate is added in the presence of nitric acid
• Bromide ions form cream precipitate when silver nitrate is added in the presence of nitric acid
• Iodide ions form white precipitate when yellow nitrate is added in the presence of nitric acid
• Advantages of using machines :

  • Very sensitive - they can detect even the tiniest amounts of substances
  • Very fast and tests can be automated
  • Very accurate - results are precise