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Questions and Answers
What type of hydrocarbon is ethyne classified as?
What type of hydrocarbon is ethyne classified as?
Which qualitative test utilizes color change to identify unsaturated hydrocarbons?
Which qualitative test utilizes color change to identify unsaturated hydrocarbons?
What is the purpose of the flammability test conducted using a lighted taper?
What is the purpose of the flammability test conducted using a lighted taper?
Which reagent is used in the Friedel-Crafts Reaction to confirm aromatic hydrocarbons?
Which reagent is used in the Friedel-Crafts Reaction to confirm aromatic hydrocarbons?
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What observable result indicates a positive Br2 Test?
What observable result indicates a positive Br2 Test?
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What was the observed flame characteristic during the flammability test for ethyne?
What was the observed flame characteristic during the flammability test for ethyne?
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Which test is capable of differentiating between aldehydes and ketones?
Which test is capable of differentiating between aldehydes and ketones?
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Which of the following is a characteristic of alkenes when tested using KMnO4?
Which of the following is a characteristic of alkenes when tested using KMnO4?
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Which liquid settled at the bottom in the given content?
Which liquid settled at the bottom in the given content?
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What does a negative result in Baeyer's Test indicate?
What does a negative result in Baeyer's Test indicate?
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What type of liquid is described as a cloudy white liquid?
What type of liquid is described as a cloudy white liquid?
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What type of reaction does potassium permanganate (KMnO₄) undergo with unsaturated hydrocarbons?
What type of reaction does potassium permanganate (KMnO₄) undergo with unsaturated hydrocarbons?
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Which of the following is a characteristic of the clear liquid mentioned at the top?
Which of the following is a characteristic of the clear liquid mentioned at the top?
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Which liquid reacted negatively to Baeyer's Test according to the results?
Which liquid reacted negatively to Baeyer's Test according to the results?
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Which substance is primarily associated with the formation of a white crystalline precipitate?
Which substance is primarily associated with the formation of a white crystalline precipitate?
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What is indicated by a colloidal precipitate formed throughout a solution?
What is indicated by a colloidal precipitate formed throughout a solution?
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What does a negative reaction to the bromine test indicate?
What does a negative reaction to the bromine test indicate?
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Which compound shows a positive reaction in the bromine test?
Which compound shows a positive reaction in the bromine test?
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What result would indicate a sample is not an alkene when tested with concentrated sulfuric acid?
What result would indicate a sample is not an alkene when tested with concentrated sulfuric acid?
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Which of the following compounds is likely to show a positive reaction in the sulfuric acid test?
Which of the following compounds is likely to show a positive reaction in the sulfuric acid test?
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A sample that retains the orangeish-brown color during the bromine test is likely to be which type of hydrocarbon?
A sample that retains the orangeish-brown color during the bromine test is likely to be which type of hydrocarbon?
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What observation is noted when using Baeyer's reagent with cyclohexane?
What observation is noted when using Baeyer's reagent with cyclohexane?
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Which reagent causes the formation of a reddish-pink color when tested with cyclohexane?
Which reagent causes the formation of a reddish-pink color when tested with cyclohexane?
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What does the presence of a cloudy white liquid in a test indicate?
What does the presence of a cloudy white liquid in a test indicate?
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Which of the following observations is NOT associated with the use of sulfuric acid?
Which of the following observations is NOT associated with the use of sulfuric acid?
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What is the expected observation when hexane is tested with Baeyer's reagent?
What is the expected observation when hexane is tested with Baeyer's reagent?
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What conclusion can be drawn from a test that results in a clear liquid when using the Friedel-Crafts reaction?
What conclusion can be drawn from a test that results in a clear liquid when using the Friedel-Crafts reaction?
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With what reagent is the test characterized by the formation of a dark orange liquid?
With what reagent is the test characterized by the formation of a dark orange liquid?
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What indicates a successful reaction in the test with AgNO3?
What indicates a successful reaction in the test with AgNO3?
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Which type of liquid is predominantly observed at the bottom after a reaction involving cyclohexane and Baeyer's reagent?
Which type of liquid is predominantly observed at the bottom after a reaction involving cyclohexane and Baeyer's reagent?
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What reaction characteristic is observed when hexane is subjected to the Br2 Test?
What reaction characteristic is observed when hexane is subjected to the Br2 Test?
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What indicates a positive reaction for a terminal alkyne in the Tollens’ Test?
What indicates a positive reaction for a terminal alkyne in the Tollens’ Test?
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Which of the following substances is classified as an aromatic hydrocarbon based on the Friedel-Crafts Reaction?
Which of the following substances is classified as an aromatic hydrocarbon based on the Friedel-Crafts Reaction?
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In the qualitative tests, what result indicates that a chemical is neither an alkene nor an alkyne?
In the qualitative tests, what result indicates that a chemical is neither an alkene nor an alkyne?
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What kind of hydrocarbon is indicated by a positive result in the Tollens’ Test?
What kind of hydrocarbon is indicated by a positive result in the Tollens’ Test?
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Which reagent is used in the Friedel-Crafts Reaction to classify aromatic hydrocarbons?
Which reagent is used in the Friedel-Crafts Reaction to classify aromatic hydrocarbons?
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Which of the following substances does not produce a positive reaction for being an alkyne?
Which of the following substances does not produce a positive reaction for being an alkyne?
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What type of reaction does the presence of a white crystalline precipitate signify in the Friedel-Crafts Reaction?
What type of reaction does the presence of a white crystalline precipitate signify in the Friedel-Crafts Reaction?
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Which of the following statements is true regarding Naphthalene?
Which of the following statements is true regarding Naphthalene?
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What was observed when Heptane reacted with pink KMnO4?
What was observed when Heptane reacted with pink KMnO4?
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What state is Ethyne in before the qualitative tests?
What state is Ethyne in before the qualitative tests?
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When observing Naphthalene, what was the appearance of the substance?
When observing Naphthalene, what was the appearance of the substance?
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What describes the precipitate formed with Heptane?
What describes the precipitate formed with Heptane?
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What type of solution did Ethyne produce in the experiment?
What type of solution did Ethyne produce in the experiment?
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What can be inferred about the first two columns in the data?
What can be inferred about the first two columns in the data?
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What color was the liquid formed with Ethyne before reacting?
What color was the liquid formed with Ethyne before reacting?
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Which characteristic is associated with the liquid when testing Naphthalene?
Which characteristic is associated with the liquid when testing Naphthalene?
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What distinguishing feature was noted for the Ethyne reaction?
What distinguishing feature was noted for the Ethyne reaction?
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What was observed regarding the liquid clarity after the initial reactions?
What was observed regarding the liquid clarity after the initial reactions?
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Study Notes
Qualitative Tests for Hydrocarbons
- Hydrocarbons are classified as alkanes, alkenes, alkynes, or aromatics
- Experiments use various qualitative tests to classify hydrocarbons
- Classification is based on physical properties such as color changes and solubility
Introduction
- Hydrocarbons are composed of carbon and hydrogen
- The experiment tests ethyne (an alkyne) and uses other reagents to classify hydrocarbons
- Qualitative tests including Baeyer's, Br2, Sulfuric acid, Tollens', and Friedel-Crafts Reactions
- These tests analyze physical properties to determine hydrocarbon type
Materials
- Reagents: Calcium Carbide (CaC2), Distilled Water, Acidified Copper(II) sulfate solution, Potassium permanganate (KMnO4), Bromine in dichloromethane (DCM), Concentrated sulfuric acid (H2SO4), Silver nitrate (AgNO3), Ammonium Hydroxide (NH4OH), Benzene, and Aluminum Chloride (AlCl3)
- Equipment: Conical Flask, Test tubes and holders, Dropper, Lighted Paper, and Water bath setup
Methodology
- Generation, Collection, and Testing of Ethyne Gas: Calcium carbide (CaC2) reacted with distilled water, Purified gas using acidified copper(II) sulfate solution, Collected in test tubes submerged in water, and Tested flammability with a lighted taper
- Qualitative Tests (Experiment Proper): KMnO4 added to samples; product observed, Bromine in DCM added; product observed, H2SO4 added to samples; product observed, 5% AgNO3 and NH4OH mixture used; product observed, and Benzene and AlCl3 combined in DCM; product observed
Experiment Results
- Data Presentation and Conclusion: Qualitative tests results are presented to classify different hydrocarbon types
Flammability Test for Ethyne
- A luminous, smoky flame with soot was formed
- This confirms the presence of ethyne
Observations and Results
- Data table presenting observations of physical properties of various reagents under qualitative tests
- Table displays initial form of reagents and results under different tests (Baeyer's, Br2, Sulfuric Acid, Tollens', and Friedel-Crafts)
Results of Baeyer's Test
- Potassium permanganate (KMnO4) reacts with unsaturated hydrocarbons
- Positive reaction: Pink to Brown = alkene or alkyne
- Negative reaction: Retains the pink color = alkane or aromatic
Results of Br2 Test
- Bromine in dichloromethane (DCM) detects unsaturated hydrocarbons
- Positive reaction: Orangeish-Brown to Clear / Slight yellow = alkene or alkyne
- Negative reaction: Retains the Orangeish-Brown color = alkane or aromatic
Results of Sulfuric Acid Test
- Concentrated Sulfuric Acid (H2SO4) reacts with unsaturated hydrocarbons (alkene).
- Positive reaction: Exothermic change (heat) or darkening of color = alkene
- Negative reaction: No change in temperature or retains the colorless appearance = alkane or aromatic
Results of Tollens' Test
- Tollens' reagent (AgNO3 and NH4OH) detects terminal alkynes
- Positive reaction: Silver-mirror compound = terminal alkyne
- Negative reaction: No silver-mirror compound formed = not an alkyne
Results of Friedel-Crafts Reaction
- Aluminum chloride (AlCl3) in DCM reacts with aromatic hydrocarbons
- Positive reaction: White crystalline precipitate = aromatic hydrocarbon
- Negative reaction: No white crystalline precipitate formed = not an aromatic hydrocarbon
Conclusion
- Classification of reagents based on the qualitative tests
- Cyclohexane, hexane, and heptane are alkanes, ethyne is an alkyne, and naphthalene, corn oil, and benzene are aromatic
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Description
This quiz covers the qualitative tests used to classify hydrocarbons, including alkanes, alkenes, alkynes, and aromatics. Participants will explore the various physical properties and reactions that help identify different types of hydrocarbons through experiments. The quiz incorporates specific reagents and equipment essential for conducting these tests.
