Electrolysis and Electroplating Quiz
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Questions and Answers

Which metal can be reduced from its oxide using heat alone?

  • Lead
  • Copper
  • Silver
  • Mercury (correct)

    • What type of electrode is used in the electrolysis of molten lead bromide?

  • Inert graphite (correct)
  • Active graphite
  • Copper
  • Inert platinum

    • Which solution is used in the electrolysis of copper(II) sulfate?

  • H2O
  • CuSO4 (correct)
  • AgNO3
  • PbBr2

    • What is the stability characteristic of the oxides mentioned?

    <p>Least stable</p> Signup and view all the answers

    What type of electrolyte is used in the electrolysis of acidified water?

    <p>H2O (H2SO4)</p> Signup and view all the answers

    What characteristic defines the copper electrode in copper(II) sulfate electrolysis?

    <p>Active electrode</p> Signup and view all the answers

    Which metal is considered least stable based on the oxides referenced?

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

    What is the process by which copper oxide is primarily reduced?

    <p>Thermal decomposition</p> Signup and view all the answers

    What is the primary purpose of electroplating a metal?

    <p>To prevent corrosion or rusting of the base metal</p> Signup and view all the answers

    Which condition must be met for the article undergoing electroplating?

    <p>It must be placed at the cathode</p> Signup and view all the answers

    What role does the anode play in the electroplating process?

    <p>It dissolves and releases metal ions into the solution</p> Signup and view all the answers

    What should the electrolyte used in electroplating contain?

    <p>Ions of the metal intended for plating</p> Signup and view all the answers

    Why is a low current used for a longer time during electroplating?

    <p>To maximize the deposition of metal on the cathode</p> Signup and view all the answers

    Which of the following metals can be deposited during electroplating?

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

    What happens to a base metal like iron when it is electroplated with nickel?

    <p>It becomes protected against corrosion</p> Signup and view all the answers

    What would be the consequence of using a higher current during electroplating?

    <p>Uneven metal deposition</p> Signup and view all the answers

    What is the primary reason Al2O3 requires electrolysis for aluminum extraction?

    <p>Aluminum has a strong affinity for oxygen which makes conventional reduction inefficacious.</p> Signup and view all the answers

    Which process is involved in the cathode reaction for aluminum extraction?

    <p>Reduction of Al3+ ions with the addition of electrons.</p> Signup and view all the answers

    What would be the result of trying to reduce Al2O3 using carbon?

    <p>Failure to reduce Al2O3 due to aluminum's affinity for oxygen.</p> Signup and view all the answers

    What is the expected reaction when using conventional reducing agents like C, CO, and H2 on less stable metallic oxides?

    <p>They will successfully reduce the metal oxides to the corresponding metals.</p> Signup and view all the answers

    Which equation correctly represents the decomposition of mercury(II) oxide?

    <p>2HgO → Hg + O2</p> Signup and view all the answers

    What occurs at the anode during aluminum extraction?

    <p>Reduction of O2- ions to oxygen gas.</p> Signup and view all the answers

    What is the overall reaction for the electrolysis of Al2O3?

    <p>2Al2O3 + electricity → 4Al + 3O2</p> Signup and view all the answers

    Which of the following statements about Al2O3 is true regarding its stability?

    <p>Al2O3 exhibits higher stability due to aluminum's strong affinity for oxygen.</p> Signup and view all the answers

    Which metal is extracted using electrolysis due to its high stability in oxide form?

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

    What is the role of the cathode during the electrolysis of fused sodium chloride?

    <p>Reduction of Na+ ions</p> Signup and view all the answers

    In the electrolysis of fused calcium chloride, what ion is produced at the anode?

    <p>Cl2</p> Signup and view all the answers

    Which statement best describes metals extracted by electrolysis?

    <p>They are higher in the electrochemical series.</p> Signup and view all the answers

    Which electrolyte is used for the extraction of metallic sodium through electrolysis?

    <p>Fused sodium chloride</p> Signup and view all the answers

    What product is formed at the anode during the electrolysis of fused sodium chloride?

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

    In the context of electrometallurgy, what is the primary reason for using electrolysis?

    <p>To reduce metal oxides to their elemental form.</p> Signup and view all the answers

    What is the standard role of electrolytes in the electrolysis process?

    <p>Electrolytes conduct electricity and provide ions.</p> Signup and view all the answers

    What is the correct product formed at the cathode during the plating of nickel?

    <p>Ni powder</p> Signup and view all the answers

    In the electroplating process of silver, which reaction occurs at the anode?

    <p>2Ag - 2e- → 2Ag1+</p> Signup and view all the answers

    Which copper ion reaction occurs at the cathode during copper electroplating?

    <p>Cu2+ + 2e- → Cu</p> Signup and view all the answers

    What is the byproduct formed at the anode when plating copper?

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

    What role does the thick block of nickel play in the electroplating process?

    <p>It acts as the anode.</p> Signup and view all the answers

    What is the product formed at the cathode during the electrolysis of PbBr2?

    <p>Lead metal</p> Signup and view all the answers

    Which of the following represents an anode reaction during electrolysis?

    <p>Br1- - 1e- → Br</p> Signup and view all the answers

    During the electrolysis of H2SO4, which gaseous product is generated at the anode?

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

    In the electrorefining of copper, what ion is reduced at the cathode?

    <p>Cu2+</p> Signup and view all the answers

    What is the role of OH1- in the electrolysis of H2O?

    <p>By-product at the anode</p> Signup and view all the answers

    What is the primary purpose of electroplating Nickel?

    <p>To enhance corrosion resistance</p> Signup and view all the answers

    Which solution is the electrolyte used for silver electroplating?

    <p>Na [Ag(CN)2]</p> Signup and view all the answers

    During the electrolysis of CuSO4 solution, what occurs at the cathode?

    <p>Reduction of Cu2+ ions</p> Signup and view all the answers

    Study Notes

    Electrolytes and Non-Electrolytes

    • Electrolytes are substances that conduct electricity when dissolved in water or molten.
    • Non-electrolytes do not conduct electricity when dissolved in water or molten.
    • Examples of electrolytes include acids, bases, and salts (e.g., NaCl, CuSO4).
    • Examples of non-electrolytes include alcohol, sugar, and some organic compounds.
    • Strong electrolytes dissociate completely into ions in solution.
    • Weak electrolytes dissociate partially.

    Electrolysis

    • Electrolysis is the decomposition of a chemical compound (electrolyte) by passing a direct electric current through it.
    • It involves the discharge of ions at the electrodes.
    • At the cathode (negative electrode), cations gain electrons (reduction).
    • At the anode (positive electrode), anions lose electrons (oxidation).
    • The process is a redox reaction (oxidation and reduction).

    Electrolytic Cells

    • Electrolytic cells are devices used for electrolysis.
    • They contain electrodes (anode and cathode) immersed in an electrolyte solution.
    • Electrodes are usually made of metal or graphite.
    • The cell is connected to a battery to supply the direct current.

    Electrode Reactions

    • Oxidation occurs at the anode, where anions lose electrons, forming neutral atoms or molecules.
    • Reduction occurs at the cathode, where cations gain electrons, forming neutral atoms or molecules.
    • The nature of the electrodes and the concentration of ions in the electrolyte influence the discharge of ions.

    Factors Affecting Electrolysis

    • The position of the ion in the electrochemical series affects its ease of discharge.
    • Higher concentration ions have a greater chance of being discharged.
    • The nature of the electrode can influence which ion is discharged.

    Electrolysis of Molten Lead Bromide

    • Lead bromide (PbBr₂) is a molten electrolyte.
    • Molten lead bromide dissociates into Pb²⁺ and 2Br⁻ ions.
    • Lead (Pb) is deposited at the cathode.
    • Bromine (Br₂) is produced at the anode.

    Electrolysis of Acidified Water

    • Acidified water (H₂O with a small amount of H₂SO₄) is an electrolyte.
    • Water dissociates into H⁺ and OH⁻ ions.
    • H⁺ ions are discharged at the cathode, forming hydrogen gas (H₂).
    • OH⁻ ions are discharged at the anode, forming oxygen gas (O₂).

    Electrolysis of Aqueous Copper (II) Sulphate

    • Aqueous copper (II) sulphate (CuSO₄) is an electrolyte.
    • Copper (Cu²⁺) and sulphate (SO₄²⁻) ions are present.
    • At the cathode, Cu²⁺ ions gain electrons to produce copper metal (Cu).
    • At the anode, copper metal (Cu) loses electrons, producing Cu²⁺ ions, which remain in the solution.
    • The color of the solution does not change with the copper electrodes.

    Electroplating

    • Electroplating is the process of depositing a thin layer of a metal onto another metal using electrolysis.
    • The object to be plated acts as the cathode.
    • The metal to be plated acts as the anode.
    • An electrolyte containing ions of the plating metal is used.
    • A direct current is used to carry out the process.

    Electrorefining

    • Electrorefining is the process of purifying a metal using electrolysis.
    • An impure block of metal acts as the anode.
    • A pure sheet of the same metal acts as the cathode.
    • An electrolyte containing ions of the metal is used.
    • Impurities from the impure metal settle at the bottom of the cell, forming anode mud.

    Electrochemical Series

    • The electrochemical series arranges metals in order of their reactivity.
    • Easily oxidized metals (those that lose electrons readily) are at the top of the series, and those that are less easily oxidized are at the bottom.
    • Metals at the top of the series are more reactive.

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    Description

    Test your knowledge on the principles of electrolysis and electroplating with this quiz. Questions cover topics such as metal reduction, electrolytes, and the characteristics of various electrodes. Perfect for students studying chemistry concepts related to these processes.

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