Alcohol Reactions Quiz
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Questions and Answers

What is the outcome when alcohol undergoes intermolecular dehydration at lower temperatures?

  • Formation of a carboxylic acid
  • Production of an alkene
  • Creation of an ether (correct)
  • Synthesis of an aldehyde

    • Which of the following best describes an elimination reaction involving alcohols?

  • Increased number of C-H bonds in the product
  • Formation of a single compound from two reactants
  • Removal of two groups leading to a multiple bond (correct)
  • Addition of groups leading to a saturated compound

    • What is a characteristic of organic oxidation related to alcohols?

  • Formation of ethers
  • Increase in the number of C-H bonds
  • Decrease in the number of C-H bonds (correct)
  • Decreased molecular weight

    • Which of the following substances can act as a mild oxidizing agent for primary and secondary alcohols?

    <p>Potassium permanganate</p> Signup and view all the answers

    Which step in the halogenation of alcohols involves substituting a halogen atom for a hydroxyl group?

    <p>Production of alkyl halides</p> Signup and view all the answers

    What is the primary factor that influences the boiling point of alcohols?

    <p>The number of hydroxyl groups present</p> Signup and view all the answers

    Which of the following tests is specifically used to differentiate between aldehydes and ketones?

    <p>Tollens’ Silver Mirror Test</p> Signup and view all the answers

    What reaction occurs during intramolecular alcohol dehydration?

    <p>Both H and OH are removed from the same molecule</p> Signup and view all the answers

    How does the solubility of alcohols in water change with the length of the carbon chain?

    <p>Solubility decreases after three carbons</p> Signup and view all the answers

    Which of the following describes the combustion reaction of alcohols?

    <p>Alcohols react with oxygen to produce carbon dioxide and water</p> Signup and view all the answers

    What is the purpose of the Lucas Test in the context of alcohol classification?

    <p>To differentiate between primary, secondary, and tertiary alcohols</p> Signup and view all the answers

    Which of the following factors does NOT influence the physical properties of alcohols?

    <p>Temperature of the environment</p> Signup and view all the answers

    What kind of reaction is ester formation from alcohols classified as?

    <p>Dehydration synthesis reaction</p> Signup and view all the answers

    What is the physical state of C1 and C2 aldehydes at room temperature?

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

    Which factor causes aldehydes and ketones to have higher boiling points than alkanes?

    <p>Dipole-dipole interactions</p> Signup and view all the answers

    What is the water solubility characteristic of aldehydes and ketones with six or more carbon atoms?

    <p>Soluble in organic solvents but not in water</p> Signup and view all the answers

    Which oxidizing agent is commonly used in the oxidation of aldehydes and ketones?

    <p>Potassium dichromate</p> Signup and view all the answers

    Hemiacetal formation is classified as what type of reaction?

    <p>Addition reaction</p> Signup and view all the answers

    What type of reaction leads to acetal formation from a hemiacetal?

    <p>Condensation reaction</p> Signup and view all the answers

    What is the characteristic odor of higher molecular mass aldehydes (above C8)?

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

    What is a common reducing agent used in the reduction of aldehydes and ketones?

    <p>Hydrogen gas</p> Signup and view all the answers

    What is the purpose of adding distilled water in the solubility test of alcohols?

    <p>To determine the miscibility of alcohol with water</p> Signup and view all the answers

    Which step is NOT involved in the preparation of esters using the procedure described?

    <p>Adding phenol to the test tube</p> Signup and view all the answers

    What indicates that an alcohol is miscible with water during the solubility test?

    <p>No cloudiness observed after shaking</p> Signup and view all the answers

    In the ester formation process, what role does concentrated sulfuric acid play?

    <p>It acts as a catalyst for the esterification reaction</p> Signup and view all the answers

    What is the correct temperature to maintain for the water bath during ester formation?

    <p>60 degrees Celsius</p> Signup and view all the answers

    What must be done after heating the test tube in the water bath during ester formation?

    <p>Cool the test tube in cold water</p> Signup and view all the answers

    What components are combined to produce esters according to the provided procedure?

    <p>Carboxylic acids and alcohols</p> Signup and view all the answers

    What indicates the need to continue adding distilled water during the solubility test?

    <p>Appearance of cloudiness</p> Signup and view all the answers

    What is the correct volume ratio of Fehling's A to Fehling's B when preparing Fehling’s reagent?

    <p>1 part A to 1 part B</p> Signup and view all the answers

    Which component is NOT used in the preparation of Fehling’s B?

    <p>Copper sulfate pentahydrate</p> Signup and view all the answers

    What is the correct order of steps to prepare acidic potassium dichromate for oxidizing alcohols?

    <p>Dissolve 3g of K2Cr2O7 in 80 mL distilled water, then add 10 mL of conc. H2SO4 with stirring.</p> Signup and view all the answers

    What is the appropriate observation period for Fehling’s test?

    <p>10-15 minutes</p> Signup and view all the answers

    What is a significant hazard associated with using concentrated hydrochloric acid (HCl) during the experiment?

    <p>It can irritate the skin and is corrosive.</p> Signup and view all the answers

    What is an important precaution to take while using Tollens’ reagent?

    <p>Do not store unused reagent</p> Signup and view all the answers

    During the Lucas Test, what should be observed to indicate a positive result?

    <p>Formation of a cloudy suspension or two distinct layers.</p> Signup and view all the answers

    What is the first step in the Iodoform test?

    <p>Add 20 drops of 10% KI solution</p> Signup and view all the answers

    How should the acidic potassium dichromate solution be handled during the oxidation of alcohols?

    <p>Always wear gloves and protective eyewear due to its corrosive nature.</p> Signup and view all the answers

    What happens if excess ammonia is added during the preparation of Tollens’ reagent?

    <p>It may prevent the test from working properly</p> Signup and view all the answers

    What temperature should the water bath be maintained at during the oxidation process of alcohols?

    <p>60 degrees Celsius.</p> Signup and view all the answers

    Which of the following is NOT a step in the Tollens’ Silver Mirror Test?

    <p>Place in a beaker of cold water</p> Signup and view all the answers

    What is the purpose of adding DNP reagent in the 2,4-Dinitrophenylhydrazine Test?

    <p>To identify the presence of carbonyl groups through precipitate formation.</p> Signup and view all the answers

    What indicates a positive result in the Iodoform test?

    <p>Formation of a yellow precipitate</p> Signup and view all the answers

    What should be noted about the preparation of the DNP reagent?

    <p>It must be freshly prepared before each use to ensure reactivity.</p> Signup and view all the answers

    What is a common characteristic of highly corrosive substances like ZnCl2 used in the experiments?

    <p>They can cause serious skin and respiratory damage.</p> Signup and view all the answers

    Which of the following correctly describes an oxidation reaction in organic chemistry?

    <p>It decreases the number of C-H bonds.</p> Signup and view all the answers

    What distinguishes aldehydes from ketones in terms of oxidation?

    <p>Aldehydes can be oxidized to carboxylic acids.</p> Signup and view all the answers

    Which of the following statements about the Tollens’ Silver Mirror Test is true?

    <p>It involves the reduction of silver(I) ion to silver metal.</p> Signup and view all the answers

    Which oxidizing agent is specifically mentioned as capable of oxidizing aldehydes to carboxylic acids?

    <p>Potassium dichromate.</p> Signup and view all the answers

    In the 2,4-Dinitrophenylhydrazine Test, what does a positive result indicate?

    <p>The presence of carbonyl compounds.</p> Signup and view all the answers

    When comparing the oxidation of secondary alcohols to that of primary alcohols, which statement is accurate?

    <p>Secondary alcohols oxidize to ketones more readily than primary ones to aldehydes.</p> Signup and view all the answers

    What is a characteristic of the 2,4-Dinitrophenylhydrazine Test?

    <p>It is a qualitative test for carbonyl presence.</p> Signup and view all the answers

    Which of the following correctly identifies a characteristic reaction of ketones?

    <p>They are resistant to oxidation reactions.</p> Signup and view all the answers

    Which statement accurately describes the solubility of alcohols in water as the carbon chain length increases?

    <p>Solubility rapidly decreases beyond three carbon atoms.</p> Signup and view all the answers

    What mechanism primarily describes the formation of esters from carboxylic acids and alcohols?

    <p>Fischer esterification in an acidic medium</p> Signup and view all the answers

    Which type of alcohol does the Lucas Test fail to categorize?

    <p>Water insoluble alcohols with over three carbon atoms</p> Signup and view all the answers

    What can be concluded about the odor of esters formed from acetic acid and specific alcohols?

    <p>Esters from acetic acid typically have a fruity smell.</p> Signup and view all the answers

    What is the primary observation to indicate a positive result during the Lucas Test?

    <p>Appearance of turbidity or a colored layer</p> Signup and view all the answers

    Which reaction categorizes aldehydes and ketones following the 2,4-Dinitrophenylhydrazine Test?

    <p>Generation of colored precipitates upon reaction</p> Signup and view all the answers

    Which equation best represents the oxidation of alcohols using acidic potassium dichromate?

    <p>R-OH + Cr2O7^2- + H^+ → R-COOH + Cr^3+</p> Signup and view all the answers

    What role does the carbocation play in the Lucas Test?

    <p>Serves as an intermediate in alcohol classification</p> Signup and view all the answers

    What classifies the reaction producing esters as a condensation process?

    <p>Water is produced as a byproduct of ester formation.</p> Signup and view all the answers

    What is the primary characteristic of the reaction involved in the Iodoform Test?

    <p>Oxidation of methyl ketones to give a yellow precipitate</p> Signup and view all the answers

    Study Notes

    Prayer Before Class

    • Holy Spirit, Divine Creator, true source of light and wisdom
    • Pour forth your brilliance, dispel darkness of sin and ignorance
    • Grant a penetrating mind to understand
    • Grant a retentive memory and ease of learning
    • Guide the beginning and progress of work, to successful completion
    • Ask through Jesus Christ, true God and man, forever and always
    • Amen

    Activity 4: Classification Tests for Hydroxyl- and Carbonyl-containing Compounds

    • Inorganic and Organic Chemistry Laboratory

    Unit Intended Learning Outcome

    • Distinguish compounds as hydroxyl or carbonyl containing
    • Differentiate the three types of alcohols
    • Differentiate aldehydes from ketones
    • Illustrate chemical equations involved in different reactions
    • Explain mechanisms involved in differentiating tests

    Topic Outline

    • Properties of Alcohol, Ketones, and Aldehydes
    • Laboratory Procedures
    • Solubility of Alcohols in Water
    • Ester Formation
    • Lucas Test
    • Oxidation of Alcohols using Acidic Potassium Dichromate
    • 2,4-Dinitrophenylhydrazine Test
    • Fehling's Test
    • Tollens' Silver Mirror Test
    • Iodoform Test

    Physical Properties of Alcohols

    • Depend on whether the polar or nonpolar portion dominates
    • Determining factors:
      • Length of nonpolar carbon chain
      • Number of polar hydroxyl groups
    • Boiling point increases as length of carbon chain increases, as number of hydroxyl groups increases
    • Water Solubility increases until 3 carbons, then rapidly decreases

    Chemical Properties of Alcohols

    • Combustion: Alcohol + O2 → CO2 + Water
    • Intramolecular Alcohol Dehydration:
    • chemical reaction in which the components of water are removed from a single reactant or two reactants
    • conditions: 180°C temperature, sulfuric acid (catalyst)
    • Intermolecular Alcohol Dehydration:
    • at lower temperature (140 °C) , intermolecular process to produce an ether
    • Oxidation:
      • Set of operational rules for organic redox
      • Organic oxidation increases number of C-O bonds, decreases number of C-H bonds
      • Organic reduction decreases number of C-O bonds, increases number of C-H bonds
      • Primary and secondary alcohols readily undergo oxidation in presence of mild oxidizing agents
        • Oxidizing agents: potassium permanganate, potassium dichromate, chromic acid
        • Primary alcohol → aldehyde → carboxylic acid
        • Secondary alcohol → ketone
        • Tertiary alcohol → no reaction
    • Halogenation: halogen atom substituted for hydroxyl group, producing alkyl halide
      • Source of halogen atoms: PBr3, PCl3
      • Heat is required
    • Results in the formation of an alkyl halide

    Chemical Properties of Aldehydes and Ketones

    • Oxidation:
      • Aldehyde → carboxylic acid
      • Ketone → no reaction
    • Reduction:
      • Aldehyde → primary alcohol
      • Ketone → secondary alcohol

    Procedures for Characteristic Reactions of Hydrocarbons

    • Refer to pages 55-60 for materials and specific procedure.

    Materials Needed

    • 250 mL beakers
    • Test tubes, with screw caps
    • Pipettes
    • Hot plate
    • Colorless vials
    • Test tube holder
    • Test tube brush
    • Spatula
    • Glass dropper

    A. Solubility of Alcohols in Water

    • 10 drops of each alcohol sample into separate test tubes
    • 1 mL of distilled water dropwise to each test tube
    • Shake mixture thoroughly
    • If cloudy, continue adding distilled water 10 drops at a time with vigorous shaking until producing a homogeneous dispersion
    • Note down results
    • If no cloudiness forms after Step 2, alcohol is miscible with water

    B. Ester Formation

    • Place 10 drops of carboxylic acid and 10 drops of alcohol into test tube
    • Add 4 drops of concentrated sulfuric acid to the test tube
    • Pour 150 mL of tap water into a 250mL beaker
    • Place test tubes in beaker of tap water, and heat water on hot plate to 60°C
    • Leave test tubes in water bath for 15 minutes
    • Cool test tubes by immersing in another beaker of cold water
    • Add 5 mL of distilled water to the test tube
    • Carefully note the odor of the ester formed (by holding the test tube 30 cm from your nose, gently waft vapor towards your nose). Compare observed odor to the odor of the ester in the table.

    C. Lucas Test

    • Place 2-3 drops of each alcohol into separate test tubes with screw caps
    • Add 1mL of Lucas reagent to the test tube
    • Cap the test tube and shake vigorously
    • Allow to stand at room temperature
    • Observe the rate of formation of a cloudy suspension or 2 layers

    D. Oxidation of Alcohols using Acidic Potassium Dichromate

    • Dissolve 3g of K2Cr2O7 in 80 mL of distilled water.
    • Slowly add 10 mL of concentrated H2SO4 to the solution, stirring and cooling
    • Place 2 drops of each alcohol sample into separate test tubes
    • Add 5 drops of acidic K2Cr2O7 solution, one drop at a time, while shaking mixture
    • Place test tubes in a beaker containing 150 mL of tap water and heat the water on a hot plate to 60°C
    • Leave test tubes in water bath for 5 minutes
    • Note the color of each solution

    E. 2,4-Dinitrophenylhydrazine Test

    • Dissolve 3 g of 2,4-dinitrophenylhydrazine in 15 mL of concentrated H2SO4
    • Slowly add the solution to mixture of 20 mL water and 75 mL of 95% ethanol, stirring
    • Place 2 drops of each sample in separate test tubes
    • Add 3 drops of DNP reagent to each test tube and shake
    • Observe if a yellow or orange-red precipitate is formed
    • If not, allow the solution to stand for 15 minutes

    F. Fehling's Test

    • Prepare Fehling's A (7g copper sulfate pentahydrate dissolved in 100 mL distilled water)
    • Prepare Fehling's B ( 35g potassium sodium tartrate and 10g NaOH dissolved in 100 mL distilled water)
    • Mix equal parts of Fehling's A and B
    • Prepare 4 test tubes with 1 mL of freshly prepared Fehling's reagent
    • Add 3 drops of each sample to the test tubes
    • Place the tubes in a beaker of boiling water and observe changes (10-15 mins)
    • Avoid excessive heating and record observation

    G. Tollens' Silver Mirror Test

    • Mix 2 mL of 5% AgNO3 and 2 drops of 5% NaOH
    • Add drop by drop, 2% NH4OH while stirring, to dissolve precipitate (until ammonia is added, the test will not work properly)
    • Prepare 4 test tubes with 1 mL of freshly prepared Tollens' reagent
    • Add 2 drops of each sample separately to the test tube
    • Shake gently and observe the mixture for 10 minutes
    • If no reaction, place test tube in a beaker of 35-50°C warm water for 5 minutes and record observation
    • Dispose of reagent (neutralize with nitric acid)

    H. Iodoform Test

    • Place 2 drops of each sample in separate test tubes
    • Add 20 drops of 10% KI solution followed by 20 drops of fresh NaOCI solution.
    • Shake gently until mixing
    • Observe for yellow precipitate

    References

    • Bettelheim, F. A., Brown, M. K., Campbell, S. O., Farrell, O. and Torres, (2021). Introduction to General, Organic, and Biochemistry
    • (12th ed.) Boston, MA, USA: Cengage Learning

    End of Discussion

    • Questions are welcome

    Prayer After Class

    • Grant a mind to know God, a heart to seek God
    • Wisdom to find God and conduct pleasing to God for faithful perseverance and a hope of embracing God
    • Amen

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    Description

    Test your knowledge on the reactions involving alcohols, including intermolecular dehydration and elimination reactions. Explore characteristics of organic oxidation and the halogenation process related to alcohols. This quiz will challenge your understanding of fundamental organic chemistry concepts.

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