Which of the following compounds is primarily used in the synt... | General Science MCQ | Examoogle

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Which of the following compounds is primarily used in the synthesis of glass and as a water softener in detergents?

Sodium bicarbonate

Sodium carbonate

Calcium oxychloride

Calcium sulfate

Correct Answer

🔬 SC • Science Concept & PrincipleGeneral ScienceScience

Option B

Sodium carbonate

Quick Summary:

Sodium carbonate (commonly known as washing soda or soda ash) is widely used in the industrial synthesis of glass and acts as an effective water softener by removing permanent hardness. It precipitates dissolved calcium and magnesium ions from hard water as insoluble carbonates.

🔬SCScience SolutionConcept & Principle

💡 Explanation

💡 Everyday Analogy (Real-World Intuition)

Think of sodium carbonate as a trap that grabs unwanted minerals out of hard water, clearing the way for soap to lather effectively.

🧠 Memory Mnemonic / Shortcut Aid

S-C-G: Soda Carbonate for Glass and Softening.

🔢 Key Formulas

$\text{Na}_2\text{CO}_3$ — Sodium carbonate (Washing soda / Soda ash)

$\text{Ca}^{2+} + \text{CO}_3^{2-} \rightarrow \text{CaCO}_3$ — Precipitation of hardness-causing ions

⚙️ Working Principle

As a water softener, sodium carbonate introduces carbonate ions ( $\text{CO}_3^{2-}$ ), which react with calcium ( $\text{Ca}^{2+}$ ) and magnesium ( $\text{Mg}^{2+}$ ) ions present in hard water to form insoluble precipitates like calcium carbonate ( $\text{CaCO}_3$ ). In glass manufacturing, it acts as a flux that lowers the melting point of silica.

📌 Key Points

▸
Sodium carbonate is commercially produced via the Solvay process.
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It is referred to as soda ash in its anhydrous form and washing soda as the decahydrate ( $\text{Na}_2\text{CO}_3 \cdot 10\text{H}_2\text{O}$ ).
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It removes permanent hardness of water by precipitation rather than ion exchange.

✅ Advantages

▸
Lowers the melting point of silica, saving energy in glass making
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Effectively removes permanent hardness from water

❌ Disadvantages / Limitations

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Excess usage can make water overly alkaline and damage fabrics over time

🛠️ Applications / Uses

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Manufacture of glass, soap, and paper
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Laundry detergents as a water softener
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Textile processing and petroleum refining

📄 Additional Information

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Chemical formula for washing soda is $\text{Na}_2\text{CO}_3 \cdot 10\text{H}_2\text{O}$ .
▸
Option A (Sodium bicarbonate, $\text{NaHCO}_3$ ) is baking soda, used in antacids and fire extinguishers.
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Option C (Calcium oxychloride, $\text{CaOCl}_2$ ) is bleaching powder, used for disinfection.
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Option D (Calcium sulfate, $\text{CaSO}_4$ ) is used in making plaster of paris and drywall.

📊 Diagram / Illustration

✅

B is correct — Sodium carbonate is a key raw material for glass production and acts as a water softener by precipitating hardness-causing ions.

Core Concepts Used

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Water softening Glass manufacturing Solvay process products

💡 EXAM TIP

Remember the distinction between washing soda ( $\text{Na}_2\text{CO}_3$ ) and baking soda ( $\text{NaHCO}_3$ ), as competitive exams like RRBJE frequently test their chemical formulas and distinct uses.

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