JEE Main 2022 · Chemistry · s-Block, p-Block Elements and Hydrogen · medium

Chlorine is passed through hot concentrated NaOH solution, so that the only chlorine-containing products are NaCl and NaClO3. The mass of NaClO3…

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Chlorine is passed through hot concentrated NaOH solution, so that the only chlorine-containing products are NaCl and

\mathrm{NaClO_3}

. The mass of

\mathrm{NaClO_3}

(

M=106.5

) formed from

7.1\ \mathrm g

\mathrm{Cl_2}

is about

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Answer: (A) $3.55\ \mathrm g$

In hot concentrated alkali, chlorine disproportionates:

3\mathrm{Cl_2}+6\mathrm{NaOH}\to5\mathrm{NaCl}+\mathrm{NaClO_3}+3\mathrm{H_2O}

. Moles of

\mathrm{Cl_2}=7.1/71=0.10

. Three moles of

\mathrm{Cl_2}

give one mole of chlorate, so

\mathrm{NaClO_3}=0.10/3=0.0333

mol

=0.0333\times106.5=3.55\ \mathrm g

. In cold dilute alkali the product is hypochlorite, which would give

7.45\ \mathrm g

of NaOCl.

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