Electrochemistry and Electrolysis Quiz
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Questions and Answers

What is the primary role of the anode in an electrolysis process?

  • To attract negative ions and facilitate oxidation (correct)
  • To dissolve the electrolyte
  • To provide a source of free electrons
  • To conduct the current without reacting

    • Which of the following statements accurately describes inert electrodes?

  • They do not interfere with the electrolysis process. (correct)
  • They are always more expensive than active electrodes.
  • They can only be made from metals.
  • They participate directly in the chemical reactions during electrolysis.

    • Which statement correctly describes the behavior of ions during electrolysis?

  • Positive ions gain electrons at the anode and become neutral.
  • Negative ions are attracted to the cathode and gain electrons.
  • Positive ions are attracted to the cathode and lose electrons.
  • Negative ions lose electrons at the anode and form neutral atoms. (correct)

    • What characteristic must a substance possess to be classified as an electrolyte?

    <p>It must be capable of ionizing to conduct electric current.</p> Signup and view all the answers

    In an electrolysis experiment, which of the following materials would most likely be used as an inert electrode?

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

    What happens to the Cl- ions during the electrolysis of molten sodium chloride?

    <p>They are oxidized to form Cl2 gas.</p> Signup and view all the answers

    Why is electrolysis not possible in solid ionic compounds?

    <p>Solid ionic compounds conduct electricity poorly because they lack free mobile ions.</p> Signup and view all the answers

    During electrolysis of an aqueous solution, what determines which positive ion is discharged at the cathode?

    <p>The position of the ion in the reactivity series relative to hydrogen.</p> Signup and view all the answers

    What is the net chemical reaction when performing electrolysis on molten sodium chloride?

    <p>2NaCl(l) → 2Na(l) + Cl2(g)</p> Signup and view all the answers

    In the electrolysis of aqueous copper iodide, which ion is discharged at the cathode?

    <p>Cu2+ ions are discharged.</p> Signup and view all the answers

    Study Notes

    Electrochemistry

    • Electrolysis breaks down compounds using electricity. Electrical current is the flow of charged particles.
    • Conductors are substances that allow electric current flow (mostly metals and graphite). They contain free electrons.
    • Insulators do not allow current flow.
    • Electrolytes conduct electricity when molten or dissolved in water. This is due to free ions. Examples include acids, alkalis, and ionic compounds in solution.
    • Non-electrolytes do not conduct electricity as they do not ionize.

    Electrolysis Cell

    • An electrolysis cell has electrodes that are dipped into a liquid to be electrolyzed.
    • The positive pole is the anode.
    • The negative pole is the cathode.

    Electrodes

    • Active electrodes participate in the reaction.
    • Inert electrodes only conduct current without participating in the reaction. Graphite and platinum are common inert electrodes, graphite being cheaper.

    Electrolysis Process

    • Electrolysis decomposes ionic compounds into their constituent elements.
    • Example: Electrolysis of sodium chloride produces sodium and chlorine.
    • At the anode, negative ions lose electrons to become neutral atoms.
    • At the cathode, positive ions gain electrons to become neutral atoms.

    Electrolysis of Molten Ionic Compounds

    • Molten ionic compounds contain free ions allowing current to pass.
    • Example: In sodium chloride, Na+ ions move to the cathode (negative), and Cl- ions move to the anode (positive).
    • Products from electrolysis are sodium metal at the cathode and chlorine gas at the anode.

    Electrolysis of Aqueous Ionic Compounds

    • Aqueous solutions contain water ions (H⁺ and OH⁻) along with ions from the compound.
    • The ion that is discharged is dependent on its position in the reactivity series. H+ and OH⁻ from water are often discharged. The ion in the compound that is discharged depends on its position in the reactivity series.
    • If the ion from the ionic compound is more reactive (higher in the series) than hydrogen, the H+ from water is discharged at the cathode first.
    • When the ion in the ionic compound is less reactive (lower in the series) than hydrogen, then the ion from the ionic compound is discharged at the cathode first.
    • If the solution is concentrated the ion from the ionic compound is discharged (example of the concentrated solution).
    • If the solution is dilute, the OH⁻ from water is discharged (example of the dilute solution).

    Examples of Electrolysis

    • Electrolysis of brine (concentrated NaCl solution) produces hydrogen gas at the cathode, chlorine gas at the anode, and sodium hydroxide (an alkaline solution) remains.
    • Electrolysis of copper(II) sulfate solution results in copper metal at the cathode and oxygen gas at the anode. The solution becomes acidic because sulfuric acid is produced.

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    Description

    Test your knowledge on electrochemistry concepts including electrolysis, conductors, and electrodes. This quiz covers the important distinctions between electrolytes and non-electrolytes, as well as the structure and function of electrolysis cells. Dive into the fundamental principles of electricity in chemistry with this engaging quiz!

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