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Tollens' and Benedict's Test quiz

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  • What functional group do Tollens' and Benedict's tests detect?
    They detect aldehydes.
  • What is the main product when an aldehyde is oxidized in Tollens' or Benedict's test?
    The main product is a carboxylic acid.
  • What is the visible positive result in Tollens' test?
    A silver solid precipitate forms, creating a silver mirror on the test tube.
  • What is the oxidizing agent used in Tollens' test?
    Silver oxide and aqueous ammonia are used as the oxidizing agent.
  • What is the other name for Tollens' test?
    It is also called the silver mirror test.
  • What color precipitate indicates a positive Benedict's test?
    A brick red copper(I) oxide precipitate forms.
  • What happens to copper ions during a positive Benedict's test?
    Copper(II) ions are reduced to copper(I) ions.
  • Why don't ketones give a positive Tollens' or Benedict's test?
    Ketones cannot be oxidized without breaking carbon-carbon bonds, which these tests do not do.
  • What is the role of ammonia in Tollens' test?
    Aqueous ammonia dissolves silver oxide to form the active oxidizing agent.
  • What is the chemical formula for the solid formed in a positive Benedict's test?
    The formula is Cu2O, copper(I) oxide.
  • In what type of solution are both Tollens' and Benedict's tests performed?
    Both tests are performed in a basic solution.
  • What is the significance of the silver mirror in Tollens' test?
    It indicates the presence of an aldehyde in the tested sample.
  • What happens to the aldehyde during these oxidation tests?
    The aldehyde is oxidized to a carboxylic acid.
  • What does a negative result in Tollens' or Benedict's test suggest about the unknown compound?
    It suggests the compound is not an aldehyde, possibly a ketone or another functional group.
  • Why is it important that these tests do not break carbon-carbon bonds?
    Because the goal is to oxidize the aldehyde group only, preserving the carbon skeleton of the molecule.