Chemistry: Students Ask, We Answer!

March 26, 2009

Class X science isn't as tough as you think. So, which is THE most important chatper in your textbook? What is benzene?

These were some of the questions asked by stressed students during a live chat with Topper Chemistry Expert Amarpreet Kaur on March 26.

Here are the answers to these questions and more!

Deepitapai: What is meant by denatured alcohol?

Amarpreet Kaur: To prevent the misuse of ethanol produced for industrial use, it is made unfit for drinking purposes by adding methanol. Dyes are also added to colour it blue. This is called denatured alcohol.


Sauhard: Please tell what is decarboxylation reaction?

Amarpreet Kaur: Decarboxylation reactions are those reactions in which carbon dioxide is removed.


Deepitapai: A housewife wanted her house to be whitewashed. She bought 10 kg of quick lime from the market and dissolved it in 30 litres of water. On adding lime to water she noticed that the water started boiling even when it was not being heated. Give reason for her observation. Write the corresponding chemical equation and name the product formed.

Amarpreet Kaur: This is because lime when dissolved in water gives calcium hydroxide. This reaction is highly exothermic. So, a large amount of heat is evolved during the reaction Chemical equation: CaO + H2O .......> Ca(OH)2. The product is calcium hydroxide, also known as slaked lime.

Prasanthdj: Do we need to read the orange boxes in the text book

Amarpreet Kaur: Some extra interesting material is placed in light orange boxes in the text book for your knowledge. You will not be asked questions from these. Refer to mock papers


Ishy93: I want an answer from u mam i read this question in some book and its answer was not given. Why CaSO4.1/2H20 is called plaster of paris? How is it possible to have halfwater molecule attached to CaSO4 ?

Amarpreet Kaur: The formula of plaster of paris is CaSO4.1/2H2O. It is written in this form because 2 formula units of CaSO4 share one molecule of water. You can solve these problems to practice.


Aishwarya: Mam I want to know that if we will be asked to balance the equation?

Amarpreet Kaur: Yes, you can be asked to balance the chemical equations. Try solving mock papers.


Swati: What benzene actually is?

Amarpreet Kaur: Benzene is an aromatic organic compound having the formula C6H6.


MOIZ AKHTAR: Sir\Mam. What we mean by heteroatoms?

Amarpreet Kaur: Some organic compounds contain atoms besides carbon and hydrogen. These are heteroatoms. Examples of heteroatoms are nitrogen, oxygen and sulphur. For reference check solved board exam papers.