Which one of the following is the chemical formula of Washing Soda?
Na 2CO 3.10H 2O
Understanding the Chemical Formula of Washing Soda
The question asks for the correct chemical formula for Washing Soda. Washing soda is a common name for a specific chemical compound known chemically as sodium carbonate decahydrate. Its formula includes sodium carbonate along with water molecules that are part of its crystal structure.
Analyzing the Options for Washing Soda Formula
Let's look at the given options and identify what chemical compound each formula represents:
- Option 1:
\( \text{NaHCO}_3 \)
This formula represents sodium bicarbonate, commonly known as baking soda. Baking soda is different from washing soda and is primarily used as a leavening agent or antacid. - Option 2:
\( \text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O} \)
This formula represents sodium carbonate decahydrate. The\( \text{Na}_2\text{CO}_3 \)part is sodium carbonate, and\( 10\text{H}_2\text{O} \)indicates that ten molecules of water are associated with each formula unit of sodium carbonate in its crystalline form. This compound is indeed known as washing soda. - Option 3:
\( \text{Na}_2\text{CO}_3\cdot 5\text{H}_2\text{O} \)
This formula represents sodium carbonate pentahydrate. While it is a hydrate of sodium carbonate, it has fewer water molecules (five) compared to washing soda (ten). Washing soda specifically refers to the decahydrate form. - Option 4:
\( \text{NaOH} \)
This formula represents sodium hydroxide, commonly known as caustic soda or lye. Sodium hydroxide is a strong base used in soap making, drain cleaners, and other industrial processes. It is distinct from washing soda.
Identifying the Correct Washing Soda Formula
Based on the analysis of the options, the chemical formula that corresponds to washing soda (sodium carbonate decahydrate) is \( \text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O} \).
Comparing Common Sodium Compounds
It's helpful to distinguish between common sodium compounds that have similar names or formulas. Here's a quick comparison:
| Common Name | Chemical Name | Chemical Formula | Typical Use |
|---|---|---|---|
| Washing Soda | Sodium Carbonate Decahydrate | \( \text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O} \) |
Laundry detergent, water softener, cleaning agent |
| Baking Soda | Sodium Bicarbonate | \( \text{NaHCO}_3 \) |
Baking (leavening agent), antacid |
| Caustic Soda | Sodium Hydroxide | \( \text{NaOH} \) |
Soap making, drain cleaner, industrial processes |
| Soda Ash | Anhydrous Sodium Carbonate | \( \text{Na}_2\text{CO}_3 \) |
Glass manufacturing, chemical production |
This table clearly shows that Washing Soda is sodium carbonate decahydrate, \( \text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O} \).
Conclusion on Washing Soda's Formula
The correct chemical formula for Washing Soda is \( \text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O} \).
Revision Table: Sodium Compounds Formulas
| Compound Name | Formula |
|---|---|
| Washing Soda | \( \text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O} \) |
| Baking Soda | \( \text{NaHCO}_3 \) |
| Caustic Soda | \( \text{NaOH} \) |
| Soda Ash (Anhydrous) | \( \text{Na}_2\text{CO}_3 \) |
Additional Information on Hydrates and Washing Soda Properties
Compounds like washing soda that contain water molecules within their crystal structure are called hydrates. The dot in the formula \( \text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O} \) indicates that ten water molecules are associated with one formula unit of sodium carbonate. This water is called water of crystallization.
Washing soda is an alkaline salt. When dissolved in water, it hydrolyzes to produce a weakly alkaline solution. This alkalinity helps in saponifying greases and oils and also helps in softening hard water by precipitating calcium and magnesium ions as carbonates.
Heating washing soda drives off the water of crystallization, leaving behind anhydrous sodium carbonate (soda ash):
\( \text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O(s)} \xrightarrow{\text{Heat}} \text{Na}_2\text{CO}_3\text{(s)} + 10\text{H}_2\text{O(g)} \)
Anhydrous sodium carbonate \( (\text{Na}_2\text{CO}_3) \) is a white powder, whereas the decahydrate form \( (\text{Na}_2\text{CO}_3\cdot 10\text{H}_2\text{O}) \) consists of large, transparent crystals.
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