Fatty Acid Tests
18 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What does the blue precipitate in the lower layer indicate in the identification of fatty acids?

  • Semisame oil
  • Saturated fatty acids (correct)
  • Unsaturated fatty acids
  • Neutral fatty acids

    • Which test is used to identify cotton seed oil?

  • Salkowisk's test
  • Halphen test (correct)
  • Liebermann test
  • Baudouin's test

    • What is the result of the Liebermann test for cholesterol?

  • The solution becomes pink
  • The solution becomes yellow with green fluorescence
  • The solution becomes deep purple
  • The solution becomes red then rapidly changes to deep blue (correct)

    • What is the characteristic of cholesterol crystals under a microscope?

    <p>Appearance of a broken glass</p> Signup and view all the answers

    What is the significance of the presence of cholesterol in vegetable oils?

    <p>It indicates adulteration with fat of animal origin</p> Signup and view all the answers

    What is the result of the Baudouin's test for semisame oil?

    <p>A pink color is formed in the acid layer</p> Signup and view all the answers

    What is the result of the Borax test when glycerol is added to the solution?

    <p>A pink color reappears</p> Signup and view all the answers

    What is the purpose of the Grease stain test in the identification of fatty acids?

    <p>To distinguish between saturated and unsaturated fatty acids</p> Signup and view all the answers

    In which of the following solvents is glycerol insoluble?

    <p>Ether and chloroform</p> Signup and view all the answers

    What is the result of the Iodine test when a saturated fatty acid is added to the solution?

    <p>The pink color of iodine appears</p> Signup and view all the answers

    What is the purpose of the Copper acetate test in the identification of fatty acids?

    <p>To identify the type of fatty acid present in a sample</p> Signup and view all the answers

    What is the result of the Achroline test when glycerol is added to the solution?

    <p>Acroline compound is formed</p> Signup and view all the answers

    What is the characteristic of glycerol that makes it useful in vanishing cream?

    <p>It is very hygroscopic</p> Signup and view all the answers

    What is the main difference between oils and fats?

    <p>Oils are liquid at room temperature, while fats are solid</p> Signup and view all the answers

    What type of lipids are esters of fatty acids with glycerol or other alcohols?

    <p>Simple lipids</p> Signup and view all the answers

    What is the typical carbon atom chain length of fatty acids?

    <p>3-17 carbon atoms</p> Signup and view all the answers

    What is the process by which fats are broken down into glycerol and fatty acids?

    <p>Hydrolysis</p> Signup and view all the answers

    What is the characteristic of glycerol in terms of its solubility?

    <p>It is soluble in water and alcohol, but insoluble in ether</p> Signup and view all the answers

    Study Notes

    Fatty Acids (F.As)

    • Blue precipitate in the lower layer indicates saturated fatty acids.
    • Blue or green precipitate in the upper layer suggests unsaturated fatty acids.
    • Two clear layers signify neutral fatty acids.

    Specific Tests for Oils

    • Halphen Test: Used for cotton seed oil

      • Mix 10 ml cotton seed oil with 10 ml Halphen reagent.
      • Boil in water bath for 1 hour; a red color indicates positive result.

    • Baudouin’s Test: For sesame oil

      • Combine 1 gram sucrose with 2 ml concentrated HCl.
      • Observe pink color in the acid layer; separate layers after shaking.

    Cholesterol

    • Isolated from biliary calculi; a significant component of gallstones.
    • Plays a crucial role in atherosclerosis.
    • Not found in plant tissues; presence in vegetable oils indicates animal fat adulteration.

    Tests for Cholesterol

    • Microscopic Appearance:

      • Mix cholesterol with 2 ml alcohol; examine under a microscope post-evaporation of alcohol, observing broken glass-like crystals.

    • Salkowski’s Test:

      • In a dry test tube, combine 2 ml chloroform, cholesterol, and 2 ml concentrated H2SO4.
      • Upper chloroform layer shows deep purple; lower acid layer appears yellow with green fluorescence.

    • Liebermann Test:

      • Mix 2 ml chloroform with cholesterol, 10 drops of acetic anhydride, and 2 drops of concentrated H2SO4.
      • Color changes from red to deep blue, eventually to deep bluish-green.

    Glycerol

    • Soluble in water and alcohol; insoluble in ether and chloroform.

    Chemical Tests for Glycerol

    • Achroline Test:

      • Combine one drop of glycerol with 1g anhydrous potassium disulfide; heat until fumes form indicating formation of acroline compound.

    • Borax Test:

      • Mix 5 ml borax solution with 2 drops of phenolphthalein, then add glycerol dropwise and heat to regain pink color.

    • Benedict Test:

      • Combine 5 ml Benedict solution with 1 ml glycerol, heat; color disappears indicating no reducing action.

    • Copper Hydroxide Test:

      • Combine 1 ml copper sulfate with 1 ml NaOH and glycerol; blue color remains unchanged.

    Differentiation between Fatty Acids

    • Solubility Tests:

      • Saturated, unsaturated, and neutral fatty acids are soluble in petroleum ether and chloroform, while insoluble in water.

    • Grease Stain Test:

      • Saturated fatty acids: chalky spot on filter paper.
      • Unsaturated and neutral fatty acids: grease spot after evaporation.

    • Degree of Unsaturation (Iodine Test):

      • Fat mixed with ether or chloroform and alcoholic iodine; pink color indicates saturation, disappearance indicates unsaturation.

    • Copper Acetate Test:

      • Mix 3 ml oil with petroleum ether and an equal volume of copper acetate solution.

    Lipids Overview

    • Lipids are organic compounds soluble in ether and petroleum ether.

    Classification of Lipids

    • Physical Properties:

      • Oils: Liquid at room temperature.
      • Fats: Solid at room temperature.

    • Chemical Structure:

      • Simple Lipids: Esters of fatty acids with glycerol or other alcohols (e.g., mono-, di-, triacylglycerols).
      • Cholesterol Esters: Esters of cholesterol and fatty acids.
      • Waxes: Esters of long-chain alcohols and fatty acids.

    • Complex Lipids: Include phospholipids, glycolipids, and sphingophospholipids.

    • Derived Lipids: Hydrolytic products from simple and complex lipids.

    Glycerol Specifics

    • Not a lipid itself; derived during fat saponification.
    • Characteristics: Colorless, viscous syrup, sweet taste, soluble in water and alcohol, insoluble in ether.
    • Used in vanishing cream due to hygroscopic properties (absorbs moisture from the atmosphere).

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    This quiz covers the identification and testing of fatty acids, including saturated and unsaturated fatty acids, and specific tests for cotton seed oil and sesame oil.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser