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Difficulty: MediumAlkali Metals: Sodium Extraction, Properties, and Compounds

Arrange the following sequential steps involved in the industrial production of sodium trioxocarbonate(IV) (Na2CO3\text{Na}_2\text{CO}_3) via the Solvay process in the correct chronological order from first to last.

  1. 1Brine solution (NaCl\text{NaCl}) is saturated with ammonia gas (NH3\text{NH}_3) in an absorption tower.
  2. 2Carbon dioxide gas (CO2\text{CO}_2) is bubbled through the ammoniacal brine to form sodium hydrogen trioxocarbonate(IV) (NaHCO3\text{NaHCO}_3) precipitate.
  3. 3The precipitated sodium hydrogen trioxocarbonate(IV) (NaHCO3\text{NaHCO}_3) crystals are filtered out of the solution.
  4. 4Sodium hydrogen trioxocarbonate(IV) (NaHCO3\text{NaHCO}_3) is heated strongly (calcinated) to decompose into sodium trioxocarbonate(IV) (Na2CO3\text{Na}_2\text{CO}_3).

Answer

The correct sequence starts with saturating brine with ammonia, bubbling carbon dioxide to precipitate sodium hydrogen trioxocarbonate(IV), filtering the precipitate, and finally heating (calcinating) the sodium hydrogen trioxocarbonate(IV) to produce sodium trioxocarbonate(IV).
The Solvay process begins by dissolving ammonia gas into brine (concentrated NaCl\text{NaCl}) to form ammoniacal brine. Next, carbon dioxide gas is bubbled through this mixture to precipitate sodium hydrogen trioxocarbonate(IV) (NaHCO3\text{NaHCO}_3). The solid precipitate is then separated by filtration. Finally, the dried NaHCO3\text{NaHCO}_3 is subjected to thermal decomposition (calcination) to produce sodium trioxocarbonate(IV) (Na2CO3\text{Na}_2\text{CO}_3).

Step-by-Step Solution

1
Identify the primary raw preparation step
Ammonia gas is dissolved in concentrated sodium chloride solution (brine) to create ammoniacal brine.
Ammonia acts as a base and reacts with carbon dioxide in the subsequent step to form hydrogen trioxocarbonate ions.
2
Identify the carbonation and precipitation step
Carbon dioxide gas is passed through the ammoniacal brine in a carbonating tower.
The reaction produces ammonium chloride (NH4Cl\text{NH}_4\text{Cl}) and sodium hydrogen trioxocarbonate (NaHCO3\text{NaHCO}_3), which precipitates because of its low solubility in cold brine solution.
3
Identify the solid-liquid separation step
The mixture is filtered to isolate the solid NaHCO3\text{NaHCO}_3 crystals from the solution containing NH4Cl\text{NH}_4\text{Cl}.
Filtration separates the insoluble sodium intermediate prior to thermal conversion.
4
Identify the final chemical transformation step
The filtered NaHCO3\text{NaHCO}_3 is heated (calcinated) at around 300∘C300^\circ\text{C} to form Na2CO3\text{Na}_2\text{CO}_3, H2O\text{H}_2\text{O}, and CO2\text{CO}_2.
Thermal decomposition yields the target sodium trioxocarbonate(IV) product while recycling CO2\text{CO}_2 back into the carbonating tower.

Key Concept

The Solvay Process for Sodium Trioxocarbonate(IV) Production
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Topics

Alkali Metals: Sodium Extraction, Properties, and Compounds

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