Baking Soda vs. Washing Soda: The Formula Trap

The Hook: One makes your cake fluffy. The other cleans your clothes.
In the exam, the options look identical: Sodium Carbonate vs Sodium BI-Carbonate.
Let's fix this confusion permanently.

1. The "Soda" Confusion

FOR COOKING 🍰

Baking Soda Sodium Bicarbonate NaHCO₃

Tip: "Bi" = Buy. You Buy food to eat.
(Used in Fire Extinguishers too).

FOR CLEANING 🧼

Washing Soda Sodium Carbonate Na₂CO₃ · 10H₂O

Tip: Washing requires water. Notice the 10H₂O (10 buckets of water).

FOR SOAP 🧴

Caustic Soda Sodium Hydroxide NaOH

Strong Base. Used in making soap and paper.

2. The "Powder" Confusion

The difference between Plaster of Paris and Gypsum is just 1.5 molecules of water!

FOR CASTS 🦴

Plaster of Paris (POP) Calcium Sulfate Hemihydrate CaSO₄ · ½ H₂O

Tip: It is a dry powder, so it has only Half (½) water.

FOR CEMENT 🧱

Gypsum Calcium Sulfate Dihydrate CaSO₄ · 2H₂O

Tip: When you add water to POP, it becomes hard Gypsum (2H₂O).

FOR DISINFECTING 🚽

Bleaching Powder Calcium Oxychloride CaOCl₂

Smells strongly of Chlorine. Used to clean water.

3. Quick Fire: The "Vitriols"

• Blue Vitriol: Copper Sulfate ($CuSO_4 \cdot 5H_2O$) - It is Blue.
• Green Vitriol: Ferrous Sulfate ($FeSO_4 \cdot 7H_2O$) - Iron is Green.
• Oil of Vitriol: Concentrated Sulphuric Acid ($H_2SO_4$) - The King of Chemicals.

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Revision Flashcards

Laughing Gas

Chemical Name?

Nitrous Oxide

Formula: N₂O. (Used by dentists as anesthesia).

Dry Ice

What is it?

Solid CO₂

Solid Carbon Dioxide. It sublimates (Solid → Gas directly).

Baking Soda

Formula?

NaHCO₃

Sodium Bicarbonate.

Aqua Regia

Mixture of?

HCl + HNO₃

Ratio 3:1. Can dissolve Gold.

Exam-Style MCQs

Q1. What is the chemical formula of "Plaster of Paris"?

A) CaSO₄ · 2H₂O

B) CaSO₄ · ½H₂O

Correct! (Hemihydrate). Option A is Gypsum.

C) CaSO₄

Q2. Which compound is used for removing permanent hardness of water?

A) Baking Soda

B) Washing Soda

Correct! Sodium Carbonate is used as a water softener.

C) Bleaching Powder

Q3. "Milk of Magnesia" is chemically known as:

A) Magnesium Hydroxide

Correct! Mg(OH)₂. It is an antacid used for acidity.

B) Magnesium Sulfate

C) Magnesium Carbonate

Part of the CGL Chemistry Series.