CHEMISTRY chemical tests

• What is the test for hydrogen gas?

  Hold a lighted splint at the sample
• What happens when hydrogen is present during the test?

  The splint goes off with a squeaky pop
• How do you test for oxygen gas?

  Hold a glowing splint towards the sample
• What indicates the presence of oxygen during the test?

  The splint re-lights
• What is the test for carbon dioxide?

  Bubbling through lime water
• What happens to lime water if carbon dioxide is present?

  Lime water becomes milky or cloudy
• What happens to damp litmus paper when carbon dioxide is present?

  Turns red and then gets bleached
• How do you test for chlorine gas?

  Use universal indicator or red litmus
• What happens to litmus paper when chlorine is present?

  It turns blue
• What is the test for water?

  Use anhydrous copper(II) sulfate
• What color change indicates water is present in the test?

  Turns blue from white
• Does the test for water indicate purity?

  No, it does not show purity
• What is the first method used to test for positive ions?

  Flame test
• What is used in the flame test?

  A platinum or chrome wire
• What color indicates lithium ions in a flame test?

  Red
• What color indicates sodium ions in a flame test?

  Yellow
• What color indicates potassium ions in a flame test?

  Lilac
• What color indicates calcium ions in a flame test?

  Orange-red
• What happens when copper(II) ions react with sodium hydroxide?

  A blue precipitate forms
• What is the name of the precipitate formed with copper(II) ions?

  Copper(II) hydroxide
• What color indicates copper(II) ions in a flame test?

  Blue-green
• What precipitate forms with iron(II) ions and sodium hydroxide?

  A green precipitate forms
• What is the name of the precipitate formed with iron(II) ions?

  Iron(II) hydroxide
• What precipitate forms with iron(III) ions and sodium hydroxide?

  An orange-brown precipitate forms
• What is the name of the precipitate formed with iron(III) ions?

  Iron(III) hydroxide
• What gas is produced when ammonium ions react with sodium hydroxide?

  Ammonia gas
• What happens when dilute hydrochloric acid is added to carbonates?

  A gas is given off
• How do you confirm the presence of carbon dioxide after testing for carbonates?

  Bubbling the gas through lime water
• What indicates carbon dioxide is present in lime water?

  Lime water turns cloudy
• What is the test for sulfates?

  Add hydrochloric acid and barium chloride
• What indicates sulfate ions are present in the test?

  A white precipitate forms
• What should not be used when testing for sulfates?

  Sulfuric acid
• What is the test for halide ions?

  Add nitric acid and silver nitrate
• What indicates chloride ions are present in the test?

  A white precipitate forms
• What indicates bromide ions are present in the test?

  A green precipitate forms
• What indicates iodide ions are present in the test?

  A yellow precipitate forms
• Why is nitric acid added before silver nitrate in halide tests?

  To remove interfering ions
• What are the tests for gases and their indicators?

  • Hydrogen: Squeaky pop with lighted splint
  • Oxygen: Glowing splint re-lights
  • Carbon dioxide: Lime water turns milky
  • Chlorine: Universal indicator turns blue
• What are the tests for water and ions?

  • Water: Anhydrous copper(II) sulfate turns blue
  • Positive ions: Flame test for color indication
  • Negative ions: Various tests with specific reagents
• What are the tests for carbonates, sulfates, and halides?

  • Carbonates: Dilute HCl gives off gas, test with lime water
  • Sulfates: HCl and barium chloride form white precipitate
  • Halides: Nitric acid and silver nitrate form colored precipitates