chemical analysis

• What is purity in chemistry?

  Substance with nothing added to it
• How can you test for the purity of a substance?

  By measuring its melting and boiling points
• What does a boiling point close to the pure state indicate?

  The substance is closer to being pure
• What is the boiling point of pure water?

  100° Celsius
• Why is tap water not considered pure water?

  It contains other substances added to it
• What is a formulation in chemistry?

  A useful mixture made with a purpose
• How are formulations similar to recipes?

  They require exact amounts of components
• What are the four gas tests mentioned?

  Chlorine, oxygen, carbon dioxide, hydrogen
• How do you test for chlorine gas?

  Using litmus paper that turns white
• What happens to a glowing splint in the presence of oxygen?

  It relights
• How do you test for carbon dioxide?

  Using lime water that turns cloudy
• What indicates the presence of hydrogen gas?

  A squeaky pop sound with a burning splint
• What is the process for collecting gases during tests?

  • Use an upside-down test tube
  • Trap gas at the top
  • Alternatively, use an airtight space
• What is paper chromatography used for?

  To separate substances in a mixture
• What should you use to draw the starting line in paper chromatography?

  Pencil
• Why is pencil preferred over pen in chromatography?

  Pencil does not contain ink that mixes
• What happens when water is added to the chromatography paper?

  Water drags the substances up the page
• What does the RF value represent in chromatography?

  Distance substance moved relative to solvent
• What should the RF value be between?

  Between zero and one
• What should you do if your RF value is above one?

  Flip the numbers in the fraction
• What is the next topic after chemical analysis?

  Chemistry of the atmosphere
• What should viewers do at the end of the video?

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