Electrolysis:An Introduction

Substances that allow electric current to pass through them are called conductors. The conductors are of two types: Metallic conductors and electrolytic conductors. Metals are metallic conductors whereas some compounds like sodium chloride are electrolytic conductors. The chemical compounds that either in molten or in aqueous state allow the electric current to pass through them is known as electrolyte. The flow of electric current through electrolytic conductors (electrolytes) is due to movement of ions formed by decomposition of electrolyte. Electrolytes may be strong or weak depending on their degree of dissociation. Compounds which neither in aqueous state nor in molten state allow the electric current to pass through them are known as non-electrolytes. The process of decomposition of an electrolyte in molten or aqueous state by passing electric current that leads to the discharge of ions of electrolyte at the electrodes is known as electrolysis. Arrhenius gave the theory for electrolytic dissociation. The process of separation of ions which are already present in an ionic compound when dissolved in water or when melted is called electrolytic dissociation. For electrolytes containing more than two cations and anions discharge of ions on electrodes depends upon relative position of ions in the electrochemical series, concentration of ions in the electrolyte and nature of electrodes.

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  • Q1

    During electrolysis of acidulated water using platinum electrodes, the ions that migrate towards anode are

    Marks:1
    Answer:

    both SO42–and OH

    Explanation:

    Both the SO42– and OH migrate to the anode but only OHions will be discharged in preference to SO42– ions as the position of OHions is lower than SO42– ions in the electrochemical series.

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  • Q2

    When electrolysis of molten lead bromide is carried out, then bromide ions

    Marks:1
    Answer:

    migrate to anode.

    Explanation:

    Negatively charged bromide ion migrates towards the anode and loses an electron to form neutral bromine atom.

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  • Q3

    Solid sodium chloride does not conduct electricity due to

    Marks:1
    Answer:

    strong electrostatic forces of attraction holding the ions in place.

    Explanation:

    Sodium chloride is an ionic compound. In this compound, oppositely charged sodium ions (Na+) and chloride ions (Cl) are held together by strong electrostatic forces of attraction. As a result, ions are not free to move to conduct electricity.

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  • Q4

    Alcohol is an example of

    Marks:1
    Answer:

    non-electrolyte.

    Explanation:

    A non-electrolyte is a compound that neither in solution nor in the molten state allows an electric current to pass through it. For example– distilled water, alcohol etc.

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  • Q5

    Potassium hydroxide is a

    Marks:1
    Answer:

    strong electrolyte.

    Explanation:

    Potassium hydroxide dissociates completely in fused or aqueous state and allows a large amount of electricity to pass through it. So, it is a strong electrolyte.

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