When `CO_2` is passed through brine solution , saturated with ammonia, white crystals precipitate out these crystals are of

Options

A. `NH_4HCO_3`
B. `NH_4Cl`
C. `Na_2CO_3`
D. `NaHCO_3`

Answer

To solve the question, we need to analyze the chemical reactions that occur when CO₂ is passed through a brine solution saturated with ammonia.

### Step-by-Step Solution:

1. **Understanding the Components**:
- We have a brine solution, which is a concentrated solution of sodium chloride (NaCl) in water.
- The solution is saturated with ammonia (NH₃), meaning it contains dissolved ammonia gas.

2. **Reaction of Ammonia with Water**:
- Ammonia in water can be represented as:
\[ \text{NH}_3 + \text{H}_2\text{O} \rightleftharpoons \text{NH}_4^+ + \text{OH}^- \]
- This shows that ammonia can form ammonium ions (NH₄⁺) in solution.

3. **Passing CO₂ through the Solution**:
- When CO₂ is introduced to the solution, it reacts with the ammonia and water. The reaction can be simplified as:
\[ \text{NH}_3 + \text{H}_2\text{O} + \text{CO}_2 \rightarrow \text{NH}_4\text{HCO}_3 \]
- This reaction produces ammonium bicarbonate (NH₄HCO₃).

4. **Formation of Sodium Bicarbonate**:
- The ammonium bicarbonate can further react with sodium chloride (from the brine solution):
\[ \text{NH}_4\text{HCO}_3 + \text{NaCl} \rightarrow \text{NaHCO}_3 + \text{NH}_4\text{Cl} \]
- This reaction produces sodium bicarbonate (NaHCO₃) and ammonium chloride (NH₄Cl).

5. **Precipitation of White Crystals**:
- Sodium bicarbonate (NaHCO₃) is a white solid that precipitates out of the solution. Therefore, the white crystals that form when CO₂ is passed through the brine solution saturated with ammonia are sodium bicarbonate (NaHCO₃).

### Final Answer:
The white crystals that precipitate out are sodium bicarbonate (NaHCO₃).

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