JEE Main · 2022 · Shift-IIeasyEC-066

In the industrial production of which of the following, molecular hydrogen is obtained as a byproduct?

Electrochemistry · Class 12 · JEE Main Previous Year Question

Question

In the industrial production of which of the following, molecular hydrogen is obtained as a byproduct?

Options
  1. a

    Na2CO3\mathrm{Na_2CO_3}

  2. b

    NaOH

  3. c

    Na metal

  4. d

    NaHCO3\mathrm{NaHCO_3}

Correct Answerb

NaOH

Detailed Solution

Strategy: Identify industrial electrochemical pro\cesses (like the chlor-alkali pro\cess) and their major products and byproducts.

Brine Electrolysis (Chlor-Alkali Pro\cess): When an aqueous solution of sodium chloride (brine) is electrolyzed:

  • At the Anode: Chlorine gas is produ\ced (\ceCl2\ce{Cl2}).
  • At the Cathode: Water is redu\ced to produ\ce Hydrogen gas (\ceH2\ce{H2}).
  • In the Solution: \ceNaOH\ce{NaOH} is formed.

Among the options:

  • NaOH production is the primary industry where molecular hydrogen is obtained as a significant byproduct.
  • \ceNa2CO3\ce{Na2CO3} and \ceNaHCO3\ce{NaHCO3} are made via the Solvay pro\cess (chemical, not electrochemical).
  • Na metal requires the electrolysis of molten \ceNaCl\ce{NaCl} (Downs pro\cess), which does not involve water and thus produ\ces no hydrogen.

Answer: (b) NaOH\boxed{\text{Answer: (b) NaOH}}

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