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What is Bleaching Powder?
Grade Level:
Class 10
AI/ML, Physics, Biotechnology, Space Technology, Chemistry, Engineering, Medicine
Definition
What is it?
Bleaching powder, also known as calcium oxychloride (CaCl2), is a yellowish-white powder with a strong smell of chlorine. It is formed by the reaction of chlorine gas with dry slaked lime (calcium hydroxide). It is primarily used as a bleaching agent and a disinfectant.
Simple Example
Quick Example
Imagine you have a white cricket jersey that got stained during a match. If you want to make it look bright white again, you might use a bleaching agent. Bleaching powder works similarly, but it's a chemical compound used for bigger tasks like cleaning water or bleaching clothes in industries.
Worked Example
Step-by-Step
Let's understand the preparation of bleaching powder.
Step 1: Identify the main reactants needed. These are dry slaked lime and chlorine gas.
---Step 2: Write the chemical formula for dry slaked lime. It is Ca(OH)2.
---Step 3: Write the chemical formula for chlorine gas. It is Cl2.
---Step 4: Write the balanced chemical equation for the reaction. Ca(OH)2 (s) + Cl2 (g) → CaOCl2 (s) + H2O (l).
---Step 5: Identify the product formed other than water. This product is calcium oxychloride, which is bleaching powder.
---Answer: Bleaching powder (CaOCl2) is prepared by reacting dry slaked lime (Ca(OH)2) with chlorine gas (Cl2).
Why It Matters
Understanding bleaching powder is crucial in chemistry and daily life. Chemical engineers use this knowledge to design water treatment plants, ensuring safe drinking water for everyone. In medicine, it's vital for sanitizing hospitals and preventing the spread of diseases, making it important for public health professionals.
Common Mistakes
MISTAKE: Thinking bleaching powder is just chlorine. | CORRECTION: Bleaching powder is calcium oxychloride (CaOCl2), a compound formed from chlorine, calcium, and oxygen, not just chlorine gas (Cl2).
MISTAKE: Believing bleaching powder is used for internal medicinal purposes. | CORRECTION: Bleaching powder is a strong chemical for external use like disinfection and bleaching; it should never be consumed or used internally.
MISTAKE: Storing bleaching powder in open containers. | CORRECTION: Bleaching powder reacts with atmospheric carbon dioxide and moisture, releasing chlorine gas. It should be stored in airtight containers to maintain its effectiveness.
Practice Questions
Try It Yourself
QUESTION: What is the chemical name of bleaching powder? | ANSWER: Calcium oxychloride.
QUESTION: Write the balanced chemical equation for the preparation of bleaching powder. | ANSWER: Ca(OH)2 (s) + Cl2 (g) → CaOCl2 (s) + H2O (l)
QUESTION: Why is bleaching powder stored in airtight containers? | ANSWER: Bleaching powder reacts with carbon dioxide and moisture in the air to release chlorine gas, which reduces its effectiveness. Storing it in airtight containers prevents this reaction and preserves its properties.
MCQ
Quick Quiz
Which of the following is a primary use of bleaching powder?
As a fuel in vehicles
For making instant noodles
Disinfecting drinking water
As a fertilizer for plants
The Correct Answer Is:
C
Bleaching powder is widely used for disinfecting drinking water to kill germs and make it safe for consumption. It is not used as fuel, food, or fertilizer.
Real World Connection
In the Real World
In many Indian towns and villages, especially during monsoon season, municipal corporations add bleaching powder to water reservoirs. This helps kill harmful bacteria and germs, making the tap water safe for people to drink and use, a critical step in public health initiatives.
Key Vocabulary
Key Terms
Calcium Oxychloride: The chemical name for bleaching powder | Disinfectant: A substance used to kill germs and bacteria | Bleaching Agent: A substance used to remove color or whiten materials | Slaked Lime: Calcium hydroxide, a reactant in bleaching powder preparation | Chlorine Gas: A yellowish-green gas, also a reactant in bleaching powder preparation
What's Next
What to Learn Next
Great job learning about bleaching powder! Next, you can explore other important chemical compounds like washing soda and baking soda. Understanding their properties and uses will help you see how chemistry is all around us, from our kitchens to large industries.
