Find $A, B$ and $C$ in the following reactions: $\mathrm{NH}_{3}+\mathrm{A}+\mathrm{CO}_{2} \rightarrow\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}$ $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}+\mathrm{H}_{2} \mathrm{O}+\mathrm{B} \rightarrow \mathrm{NH}_{4} \mathrm{HCO}_{3}$ $\mathrm{NH}_{4} \mathrm{HCO}_{3}+\mathrm{NaCl} \rightarrow \mathrm{NH}_{4} \mathrm{Cl}+\mathrm{C}$

(B) $\mathrm{A}-\mathrm{H}_{2} \mathrm{O} ; \mathrm{B}-\mathrm{CO}_{2} ; \mathrm{C}-\mathrm{NaHCO}_{3}$

(A) $\mathrm{A}-\mathrm{H}_{2} \mathrm{O} ; \mathrm{B}-\mathrm{O}_{2} ; \mathrm{C}-\mathrm{NaHCO}_{3}$

(C) $\mathrm{A}-\mathrm{H}_{2} \mathrm{O} ; \mathrm{B}-\mathrm{O}_{2} ; \mathrm{C}-\mathrm{Na}_{2} \mathrm{CO}_{3}$

(D) $\mathrm{A}-\mathrm{O}_{2} ; \mathrm{B}-\mathrm{CO}_{2} ; \mathrm{C}-\mathrm{Na}_{2} \mathrm{CO}_{3}$

JEE Main · 2021 · 26 Feb 2021 · Shift 1 · General Principles and Processes of Isolation of Metals

Find

A, B

and

C

in the following reactions:

NH_{3} + A + CO_{2} \to (NH_{4})_{2} CO_{3}

(NH_{4})_{2} CO_{3} + H_{2} O + B \to NH_{4} HCO_{3}

NH_{4} HCO_{3} + NaCl \to NH_{4} Cl + C

(A) $A - H_{2} O; B - O_{2}; C - NaHCO_{3}$
(B) $A - H_{2} O; B - CO_{2}; C - NaHCO_{3}$ ✓ Correct
(C) $A - H_{2} O; B - O_{2}; C - Na_{2} CO_{3}$
(D) $A - O_{2}; B - CO_{2}; C - Na_{2} CO_{3}$

Answer: (B)

Solution

These three equations are the Solvay process for sodium carbonate. Ammonia dissolved in water takes up carbon dioxide to give ammonium carbonate, so A is water:

2 N H_{3} + H_{2} O + C O_{2} \to (N H_{4})_{2} C O_{3}

More carbon dioxide passed into that solution converts the carbonate into the hydrogencarbonate, so B is carbon dioxide:

(N H_{4})_{2} C O_{3} + H_{2} O + C O_{2} \to 2 N H_{4} HC O_{3}

Brine added to the ammonium hydrogencarbonate throws down the sparingly soluble sodium salt:

N H_{4} HC O_{3} + NaCl \to N H_{4} Cl + NaHC O_{3}

So A is

H_{2} O

, B is

C O_{2}

and C is

NaHC O_{3}

JEE Main · 2021 · 26 Feb 2021 · Shift 1 · Single correct option

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JEE Main · 2021 · 26 Feb 2021 · Shift 1 · General Principles and Processes of Isolation of Metals

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