Question

What are the raw materials used in Solvay's process?
(A) \[NaCl,N{H_3},CaC{O_3}\]
(B) \[{\text{NaOH,C}}{{\text{O}}_{\text{2}}}\]
(C) \[NaCl,CuC{O_3},C,{H_2}S{O_4}\]
(D) \[N{H_3},{H_2}O,NaCl\]

Answer 1

Hint: To solve this question we must know about Solvay’s process. Solvay’s process is industrially used to manufacture sodium carbonate. The major ingredients or reactants used in this process are salt brine and limestone.

Complete step by step solution:
In Solvay’s process, first carbon dioxide and ammonia gas is passed over a cold and saturated solution of sodium chloride. This leads to the formation of sodium hydrogen carbonate that is soluble in sodium ions and is precipitated that can be removed by filtration. Sodium chloride is then reacted with sodium hydrogen carbonate to give sodium bicarbonate with on heating gives sodium carbonate.
Step 1: Ammonia, water and carbon dioxide react to form ammonium carbonate, which on further reaction with water and carbon dioxide forms ammonium bicarbonate.
\[
  2N{H_3} + {H_2}O + C{O_2}\xrightarrow{{}}{(N{H_4})_2}C{O_3} \\
  {(N{H_4})_2}C{O_3} + {H_2}O + C{O_2}\xrightarrow{{}}2N{H_4}HC{O_3} \\
\]
Step 2: Ammonium bicarbonate is then added to sodium chloride, which results in the formation of ammonium chloride and sodium bicarbonate.
\[N{H_4}HC{O_3} + NaCl\xrightarrow{{}}N{H_4}Cl + NaHC{O_3}\]
Step 3: Sodium bicarbonate on further heating results in the formation of sodium carbonate and carbon dioxide gas is evolved which can be reused in the process again
\[2NaHC{O_3}\xrightarrow{{}}N{a_2}C{O_3} + {H_2}O + C{O_2}\]
So the raw materials used in this process are sodium chloride, ammonia and limestone.

Hence the correct option is (A).

Note: Sodium carbonate can also be prepared from trona ore. Trona ore has a formula of \[N{a_2}C{O_3}.NaHC{O_3}.2{H_2}O\]. That on heating results in the formation of sodium carbonate.\[2N{a_2}C{O_3}.NaHC{O_3}.2{H_2}O\xrightarrow{{}}3N{a_2}C{O_3} + 5{H_2}O + C{O_2}\]. The structure of this Trona Ore consists of units of 3 edge-sharing sodium polyhedral (a central octahedron flanked by septahedra), cross-linked by carbonate groups and hydrogen bonds.