Practical 7.1: Gas Tests for Oxygen and Carbon Dioxide
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Questions and Answers

What observation should be made when a glowing splint is introduced into tube C?

  • The splint remains lit without change.
  • The splint emits smoke.
  • The splint ignites and burns brightly. (correct)
  • The splint goes out immediately.

    • What should happen to the hydrogen carbonate indicator after 10 drops are added to tube D?

  • It changes color from red to yellow. (correct)
  • It bubbles and fizzes.
  • It turns yellow permanently.
  • It remains colorless indefinitely.

    • What result indicates the presence of carbon dioxide when lime water is added to tube E?

  • It turns cloudy. (correct)
  • It produces a gas.
  • It changes to pink.
  • It remains colorless.

    • In the experiment with nitrogen in tubes K to O, which observation is expected?

    <p>The burning splint extinguishes quickly.</p> Signup and view all the answers

    What gas is indicated if a splint is placed in a test tube and the result shows the splint continues to glow?

    <p>Oxygen.</p> Signup and view all the answers

    What is a necessary precaution when conducting the test for oxygen?

    <p>Wear safety spectacles.</p> Signup and view all the answers

    What is the expected response of the hydrogencarbonate indicator to a non-reactive gas?

    <p>It remains colorless.</p> Signup and view all the answers

    What should you do immediately after inserting a burning splint into the test tube filled with oxygen?

    <p>Observe and record the reaction immediately.</p> Signup and view all the answers

    If a student observes that lime water remains colorless after addition to tube E, what can be concluded?

    <p>The gas is nitrogen.</p> Signup and view all the answers

    What gas is typically tested using a glowing splint?

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

    When performing the experiments, if the colorless gas present in tube F does not react with the burning splint, what can it be identified as?

    <p>Nitrogen.</p> Signup and view all the answers

    Which indicator is used to test for carbon dioxide in the experiment?

    <p>Hydrogencarbonate indicator</p> Signup and view all the answers

    What is the first step in the test for identifying nitrogen?

    <p>Record the initial gas color.</p> Signup and view all the answers

    What safety measure should be followed while handling gases during the experiment?

    <p>Never directly inhale the gas.</p> Signup and view all the answers

    What observation would indicate the presence of carbon dioxide?

    <p>The solution becomes cloudy when lime water is introduced.</p> Signup and view all the answers

    Why is it important to minimize the escape of gases during testing?

    <p>It ensures accurate measurements.</p> Signup and view all the answers

    What is the initial color of dry cobalt chloride paper before any liquid is added?

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

    What color does dry cobalt chloride paper change to in the presence of water?

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

    What substance is indicated as flammable and harmful in the experiment?

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

    What precaution should be taken when using alcohol in the experiment?

    <p>Wear disposable gloves</p> Signup and view all the answers

    Which indicator is used to test for carbon dioxide in the discussion?

    <p>Lime water</p> Signup and view all the answers

    What happens to hydrogen carbonate indicator when exposed to carbon dioxide?

    <p>Turns yellow</p> Signup and view all the answers

    What is required for the test involving cobalt chloride paper?

    <p>Good ventilation</p> Signup and view all the answers

    What color change indicates the presence of moisture on cobalt chloride paper?

    <p>From blue to pink</p> Signup and view all the answers

    What role does dry cobalt chloride paper play in the test for water vapor?

    <p>It acts as an indicator that changes color in the presence of water vapor.</p> Signup and view all the answers

    Why is dry cobalt chloride paper kept in a desiccator before use?

    <p>To prevent it from absorbing moisture from the air.</p> Signup and view all the answers

    Which apparatus is NOT listed as part of the materials needed for testing water vapor?

    <p>Test tube</p> Signup and view all the answers

    What color change occurs to dry cobalt chloride paper when it comes into contact with water vapor?

    <p>It turns pink.</p> Signup and view all the answers

    What must be avoided when handling dry cobalt chloride paper?

    <p>Touching it with bare hands.</p> Signup and view all the answers

    What is the primary aim of the experiment described?

    <p>To test for the presence of water vapor.</p> Signup and view all the answers

    Which chemical reaction is NOT related to the properties of cobalt chloride paper?

    <p>Absorbing nitrogen from the atmosphere.</p> Signup and view all the answers

    Which material is specifically mentioned to be used along with dry cobalt chloride paper for water testing?

    <p>Distilled water.</p> Signup and view all the answers

    What significant discovery is attributed to Antoine Lavoisier in 1775?

    <p>The existence of oxygen</p> Signup and view all the answers

    How did the understanding of burning evolve with Lavoisier's findings?

    <p>The relationship between oxygen and combustion was clarified.</p> Signup and view all the answers

    What role did technology play in Lavoisier's discovery?

    <p>It facilitated precise measurements and observations.</p> Signup and view all the answers

    What aspect of scientific practice was evident during the discovery of oxygen?

    <p>Collaboration and competition between different scientists.</p> Signup and view all the answers

    Before Lavoisier's discovery, what was the prevailing theory about combustion?

    <p>The theory of phlogiston was widely accepted.</p> Signup and view all the answers

    Which of the following was NOT a focus of Lavoisier's investigation on burning?

    <p>Measuring the temperature of burning substances.</p> Signup and view all the answers

    What impact did Lavoisier's discovery of oxygen have on chemistry?

    <p>It unified various concepts of chemical reactions.</p> Signup and view all the answers

    What did Lavoisier's investigation suggest about the content of air?

    <p>Oxygen is a key component of air essential for burning.</p> Signup and view all the answers

    Study Notes

    Practical 7.1: Tests for Oxygen, Carbon Dioxide, and Nitrogen

    • Aim: To develop tests for identifying oxygen, carbon dioxide, and nitrogen.

    • Materials:

      • Wooden splint (6 per group)
      • Test tube rack (1 per group)
      • Gas lighter (1 per group)
      • Test tubes filled with oxygen (5)
      • Test tubes filled with carbon dioxide (5)
      • Hydrogencarbonate indicator (5)
      • Test tubes filled with nitrogen (5)
      • Limewater (5)
      • Safety spectacles

    Part I: Oxygen

    • Procedure (Oxygen):
      • Obtain five test tubes filled with oxygen (labeled A-E).
      • Observe the color of the gas in tube A and record it.
      • Remove the stopper from tube A and gently waft the gas toward your nose. Record the smell.
      • Carefully follow safety instructions, do not breathe in the gas directly.

    Testing for Oxygen, continued

    • Procedure (continued):
      • Light a wooden splint.
      • Carefully remove the stopper from tube B and immediately insert the burning splint into the tube. Observe and record your observations.
      • Light another splint and blow out the flame, creating a glowing splint.
      • Remove the stopper from tube C and immediately insert the glowing splint into the tube. Observe and record your observations.

    Part II: Carbon Dioxide

    • Procedure (Carbon Dioxide):
      • Obtain five test tubes filled with carbon dioxide (labeled F-J).
      • Repeat the steps in Part I (oxygen testing) to test the carbon dioxide samples.

    Part III: Nitrogen

    • Procedure (Nitrogen):
      • Obtain five test tubes filled with nitrogen (labeled K-O).
      • Repeat the steps in Part I (oxygen testing) to test the nitrogen samples.

    Results

    • The results of the tests will be recorded. (See provided data table)

    • Key observations:

      • Various reactions with burning and glowing splints
      • Reactions with chemical indicators (hydrogencarbonate indicator and limewater)
      • Colour changes in the indicators

    Discussion

    • Based on the results, describe tests for identifying each of the gases (oxygen, carbon dioxide, and nitrogen).
    • There might be more than one test for some gases.

    Key points (Summary)

    • Oxygen relights a glowing splint.
    • Carbon dioxide turns hydrogencarbonate indicator from red to yellow and turns limewater cloudy.
    • There is no simple test for nitrogen.

    Practical 7.2: Test for Water (Water Vapour)

    • Aim: To test for water using cobalt chloride paper.

    • Materials:

      • Dry cobalt chloride paper
      • Forceps
      • White tile
      • Distilled water
      • Dropper
      • Alcohol
      • Beaker

    • Safety: Handle cobalt chloride paper carefully. Ensure alcohol is used safely away from flames.

    Procedure 7.2

    • 1. Take out a piece of dry cobalt chloride paper, record its colour.

    • 2. Add a drop of water to the paper, record the colour change.

    • 3. Add a drop of alcohol to a separate piece of dry cobalt chloride paper, record the colour change.

    • Results: Record the colour changes for adding water and alcohol to the cobalt chloride paper.

    • Discussion: Discuss how cobalt chloride paper changes colour in the presence of water (and with alcohol). Explain the colour change.

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    Charlene Sci 7.1 Practicals PDF

    Description

    This practical quiz focuses on developing tests to identify the gases oxygen, carbon dioxide, and nitrogen. Students will follow procedures involving various materials and equipment to safely observe and record their findings. Mastering these experiments is essential for understanding gas reactions in chemistry.

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